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Background: In patients with squamous cell carcinoma of the anus (SCCA), magnetic resonance (MR) imaging is recommended for pre-treatment staging prior to chemo-radiotherapy (CRT), but large-scale evaluation of its staging performance is lacking., Methods: We re-characterised pre-treatment MRs from 228 patients with non-metastatic SCCA treated consecutively by CRT (2006-2015) at one UK cancer centre. We derived TN staging from tumour size (mrTr) and nodal involvement (mrN), and additionally characterised novel beyond TN features such as extramural vascular invasion (mrEMVI) and tumour signal heterogeneity (mrTSH). Primary outcomes were 5-year overall survival (OS) and 3-year loco-regional failure (LRF). Time-to-event analyses used Kaplan-Meier estimates; Hazard Ratios (HRs) with confidence intervals (CIs) were derived from Cox models., Results: With a median follow up of 60.9 months, 5-year OS was 74%. Poor OS was associated with increasing mrT (HR: 1.12 per cm [95% CI: 1.07-1.33]), nodal positivity (HR 2.08 [95% CI 1.23-3.52]) and mrEMVI (HR 3.66 [95% CI: 1.88-7.41]). 3-year LRF rate was 16.5%. Increased LRF was associated with increasing mrT (HR: 1.43 per cm [95% CI: 1.26-1.63]), nodal positivity (HR 2.70 [95% CI 1.39-5.24]) and mrTSH (HR 2.66 [95% CI 1.29-5.48])., Conclusions: In SCCA, the study demonstrates that mrT and mrN stages are prognostic, while mrEMVI and mrTSH may be novel prognostic factors., (© 2024. The Author(s).)

Purpose: To evaluate the diagnostic performance of diffusion-weighted imaging (DWI) in the 6-month interval post chemoradiation therapy (CRT) in determining persistent disease and whether persistent diffusion restriction on DWI at 6 months is associated with overall survival; and secondarily, to investigate the accuracy of pelvic lymph node assessment on T2-weighted imaging and DWI in the 6-month interval post CRT, in patients with squamous cell carcinoma of the anus., Methods and Materials: This retrospective study included patients with squamous cell carcinoma of the anus who underwent CRT followed by restaging rectal MRI from January 2010 to April 2020, with ≥1 year of follow-up after CRT. DW images were qualitatively evaluated by 2 junior and 2 senior abdominal radiologists to determine anal persistent disease. The reference standard for anal persistent disease was digital rectal examination/endoscopy and histopathology. Diagnostic performance was estimated using sensitivity, specificity, negative predictive value, and positive predictive value. Survival outcomes were evaluated via Kaplan-Meier analysis, and associations between survival outcomes and DWI status were tested for significance using the log-rank test. Additionally, DW and T2-weighted images were evaluated to determine lymph node status., Results: Among 84 patients (mean age, 63 ± 10.2 years; 64/84 [76%] female), 14 of 84 (17%) had confirmed persistent disease. Interreader agreement on DWI between all 4 radiologists was moderate (Light's κ = 0.553). Overall, DWI had a sensitivity of 71.4%, specificity of 72.1%, positive predictive value of 34.5%, and negative predictive value of 92.5%. Patients with a negative DWI showed better survival than patients with a positive DWI (3-year overall survival of 92% vs 79% and 5-year overall survival of 87% vs 74%), although the difference did not reach statistical significance (P = .063). All patients with suspicious lymph nodes (14/14, 100%) showed negative pathology or decreased size during follow-up., Conclusions: At 6 months post CRT, DWI showed value in excluding anal persistent disease. Persistent diffusion restriction on DWI was not significantly associated with overall survival. Pelvic nodal assessment on DWI and T2-weighted imaging was limited in predicting persistent nodal metastases., (Copyright © 2024 Elsevier Inc. All rights reserved.)

This study aimed to evaluate the prognostic value of 18 F-FDG PET/CT qualitative assessment in terms of recurrence-free survival (RFS), colostomy-free survival (CFS), and overall survival (OS) after radiation therapy (RT) of squamous cell carcinoma of the anus (SCCA). Secondary objectives were to evaluate the prognostic value of baseline and posttherapeutic quantitative 18 F-FDG PET/CT parameters in terms of RFS, CFS, and OS. Methods: We included all consecutive patients from the French multicentric cohort FFCD-ANABASE who had undergone 18 F-FDG PET/CT at baseline and 4-6 mo after RT or chemoradiotherapy for a localized SCCA. Qualitative assessments separated patients with complete metabolic response (CMR) and non-CMR. Quantitative parameters were measured on baseline and posttreatment 18 F-FDG PET/CT. RFS, CFS, and OS were analyzed using the Kaplan-Meier method. Associations among qualitative assessments, quantitative parameters, and RFS, CFS, and OS were analyzed using univariate and multivariate Cox regression. Results: Among 1,015 patients treated between January 2015 and April 2020, 388 patients (300 women and 88 men) from 36 centers had undergone 18 F-FDG PET/CT at diagnosis and after treatment. The median age was 65 y (range, 32-90 y); 147 patients (37.9%) had an early-stage tumor and 241 patients (62.1%) had a locally advanced-stage tumor; 59 patients (15.2%) received RT, and 329 (84.8%) received chemoradiotherapy. The median follow-up was 35.5 mo (95% CI, 32.8-36.6 mo). Patients with CMR had better 3-y RFS, CFS, and OS, at 84.2% (95% CI, 77.8%-88.9%), 84.7% (95% CI, 77.2%-89.3%), and 88.6% (95% CI, 82.5%-92.7%), respectively, than did non-CMR patients, at 42.1% (95% CI, 33.4%-50.6%), 47.9% (95% CI, 38.1%-56.8%), and 63.5 (95% CI, 53.2%-72.1%), respectively ( P < 0.0001). Quantitative parameters were available for 154 patients from 3 centers. The following parameters were statistically significantly associated with 3-y RFS: baseline SUV max (primitive tumor [T]) (hazard ratio [HR], 1.05 [95% CI, 1.01-1.1; P = 0.018]), SUV peak (T) (HR, 1.09 [95% CI, 1.02-1.15; P = 0.007]), MTV 41% (T) (HR, 1.02 [95% CI, 1-1.03; P = 0.023]), MTV 41% (lymph node [N]) (HR, 1.06 [95% CI, 1.03-1.1; P < 0.001]), MTV 41% (T + N) (HR, 1.02 [95% CI, 1-1.03; P = 0.005]), and posttreatment SUV max (HR, 1.21 [95% CI, 1.09-1.34; P < 0.001]). Conclusion: Treatment response assessed by 18 F-FDG PET/CT after RT for SCCA has a significant prognostic value. 18 F-FDG PET/CT could be useful for adapting follow-up, especially for patients with locally advanced-stage tumors. Quantitative parameters could permit identification of patients with a worse prognosis but should be evaluated in further trials., (© 2024 by the Society of Nuclear Medicine and Molecular Imaging.)

Demand for anal cancer screening is expected to rise following the recent publication of the Anal Cancer-HSIL Outcomes Research trial, which showed that treatment of high-grade squamous intraepithelial lesions significantly reduces the rate of progression to anal cancer. While screening for human papillomavirus-associated squamous lesions in the cervix is well established and effective, this is less true for other sites in the lower anogenital tract. Current anal cancer screening and prevention rely on high-resolution anoscopy with biopsies. This procedure has a steep learning curve for providers and may cause patient discomfort. Scattering-based light-sheet microscopy (sLSM) is a novel imaging modality with the potential to mitigate these challenges through real-time, microscopic visualization of disease-susceptible tissue. Here, we report a proof-of-principle study that establishes feasibility of dysplasia detection using an sLSM device. We imaged 110 anal biopsy specimens collected prospectively at our institution's dysplasia clinic (including 30 nondysplastic, 40 low-grade squamous intraepithelial lesion, and 40 high-grade squamous intraepithelial lesion specimens) and found that these optical images are highly interpretable and accurately recapitulate histopathologic features traditionally used for the diagnosis of human papillomavirus-associated squamous dysplasia. A reader study to assess diagnostic accuracy suggests that sLSM images are noninferior to hematoxylin and eosin images for the detection of anal dysplasia (sLSM accuracy = 0.87; hematoxylin and eosin accuracy = 0.80; P = .066). Given these results, we believe that sLSM technology holds great potential to enhance the efficacy of anal cancer screening by allowing accurate sampling of diagnostic tissue at the time of anoscopy. While the current imaging study was performed on ex vivo biopsy specimens, we are currently developing a handheld device for in vivo imaging that will provide immediate microscopic guidance to high-resolution anoscopy providers., (Copyright © 2024 United States & Canadian Academy of Pathology. Published by Elsevier Inc. All rights reserved.)

Abstract: Inflammatory increased metabolic activity was discovered in the left anal canal on an 18 F-FDG PET/CT scan performed for initial staging of anal squamous cell carcinoma in a patient with history of perianal Crohn disease. This increased uptake was due to a complex intersphincteric perianal fistula with supralevator extension, with a secondary, contiguous, superficial focus of squamous cell carcinoma at the anal verge that was identified on an MRI performed on the same day., Competing Interests: Conflicts of interest and sources of funding: none declared., (Copyright © 2024 Wolters Kluwer Health, Inc. All rights reserved.)

Gastrointestinal stromal tumours (GISTs) can develop throughout the entire gastrointestinal tract, but these tumours are usually found in the stomach and small intestine. In this case, a rare GIST arising from the anal canal was investigated using high-frequency endoanal ultrasound and external three-dimensional ultrasound with tomographic ultrasound imaging. The endoanal approach revealed the inner structure of the tumour. External ultrasound was used to determine the relationship between the lesion and surrounding tissues. In the limited reports of anal canal GISTs, no other lesions have been correctly diagnosed preoperatively or displayed in detail on imaging. The multilayer structure of the anal sphincter and these lesions can be clearly displayed by a variety of ultrasound imaging methods, which are nonradiative, low-cost and easily accessible. Modern ultrasound has the potential for broad application in anal canal tumour diagnosis and surveillance., (© 2024. Springer Nature Switzerland AG.)

Purpose: To investigate the differences in baseline staging of anal squamous cell carcinoma based on CT, MRI, and PET/CT, and the resultant impact on the radiation plan., Methods: This retrospective study included consecutive patients with anal squamous cell carcinoma who underwent baseline pelvic MRI, CT, and PET/CT (all examinations within 3 weeks of each other) from January 2010 to April 2020. CTs, MRIs, and PET/CTs were re-interpreted by three separate radiologists. Several imaging features were assessed; tumor stage was determined based on the eight edition of the American Joint Committee on Cancer (AJCC) staging manual; and T (tumor), N (node), and M (metastasis) categories were determined based on National Comprehensive Cancer Network (NCCN) guidelines. Radiologist assessments were then randomly presented to a radiation oncologist who formulated the radiation plan in a blinded fashion., Results: Across 28 patients (median age, 62 years [range, 31-78], T-category classification was significantly different on PET/CT compared to MRI and CT (p = 0.037 and 0.031, respectively). PET/CT staged a higher proportion of patients with T1/T2 disease (16/28, 57%) compared to MRI (11/28, 39%) and CT (10/28, 36%). MRI staged a higher proportion of patients with T3/T4 disease (14/28, 50%) compared to CT (12/28, 43%) and PET/CT (11/28, 39%). However, there was no significant difference between the three imaging modalities in terms of either N-category, AJCC staging, or NCCN TNM group classification, or in treatment planning., Conclusion: Our exploratory study showed that MRI demonstrated a higher proportion of T3/T4 tumors, while PET/CT demonstrated more T1/T2 tumors; however, MRI, CT, and PET/CT did not show any significant differences in AJCC and TNM group categories, nor was there any significant difference in treatment doses between them when assessed independently by an experienced radiation oncologist., (© 2024. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objectives: The incidence of anal squamous cell carcinoma (ASCC) is increasing worldwide, with a significant proportion of patients treated with curative intent having recurrence. The ability to accurately predict progression-free survival (PFS) and overall survival (OS) would allow for development of personalised treatment strategies. The aim of the study was to train and external test radiomic/clinical feature derived time-to-event prediction models., Methods: Consecutive patients with ASCC treated with curative intent at two large tertiary referral centres with baseline FDG PET-CT were included. Radiomic feature extraction was performed using LIFEx software on the pre-treatment PET-CT. Two distinct predictive models for PFS and OS were trained and tuned at each of the centres, with the best performing models externally tested on the other centres' patient cohort., Results: A total of 187 patients were included from centre 1 (mean age 61.6 ± 11.5 years, median follow up 30 months, PFS events = 57/187, OS events = 46/187) and 257 patients were included from centre 2 (mean age 62.6 ± 12.3 years, median follow up 35 months, PFS events = 70/257, OS events = 54/257). The best performing model for PFS and OS was achieved using a Cox regression model based on age and metabolic tumour volume (MTV) with a training c-index of 0.7 and an external testing c-index of 0.7 (standard error = 0.4)., Conclusions: A combination of patient age and MTV has been demonstrated using external validation to have the potential to predict OS and PFS in ASCC patients., Clinical Relevance Statement: A Cox regression model using patients' age and metabolic tumour volume showed good predictive potential for progression-free survival in external testing. The benefits of a previous radiomics model published by our group could not be confirmed on external testing., Key Points: • A predictive model based on patient age and metabolic tumour volume showed potential to predict overall survival and progression-free survival and was validated on an external test cohort. • The methodology used to create a predictive model from age and metabolic tumour volume was repeatable using external cohort data. • The predictive ability of positron emission tomography-computed tomography-derived radiomic features diminished when the influence of metabolic tumour volume was accounted for., (© 2023. The Author(s).)

Introduction: High-resolution anoscopy (HRA) is the gold standard for detecting anal squamous cell carcinoma (ASCC) precursors. Preliminary studies on the application of artificial intelligence (AI) models to this modality have revealed promising results. However, the impact of staining techniques and anal manipulation on the effectiveness of these algorithms has not been evaluated. We aimed to develop a deep learning system for automatic differentiation of high-grade squamous intraepithelial lesion vs low-grade squamous intraepithelial lesion in HRA images in different subsets of patients (nonstained, acetic acid, lugol, and after manipulation)., Methods: A convolutional neural network was developed to detect and differentiate high-grade and low-grade anal squamous intraepithelial lesions based on 27,770 images from 103 HRA examinations performed in 88 patients. Subanalyses were performed to evaluate the algorithm's performance in subsets of images without staining, acetic acid, lugol, and after manipulation of the anal canal. The sensitivity, specificity, accuracy, positive and negative predictive values, and area under the curve were calculated., Results: The convolutional neural network achieved an overall accuracy of 98.3%. The algorithm had a sensitivity and specificity of 97.4% and 99.2%, respectively. The accuracy of the algorithm for differentiating high-grade squamous intraepithelial lesion vs low-grade squamous intraepithelial lesion varied between 91.5% (postmanipulation) and 100% (lugol) for the categories at subanalysis. The area under the curve ranged between 0.95 and 1.00., Discussion: The introduction of AI to HRA may provide an accurate detection and differentiation of ASCC precursors. Our algorithm showed excellent performance at different staining settings. This is extremely important because real-time AI models during HRA examinations can help guide local treatment or detect relapsing disease., (Copyright © 2024 The Author(s). Published by Wolters Kluwer Health, Inc. on behalf of The American College of Gastroenterology.)

Introduction: The management of anal cancer relies on clinical and histopathological features for treatment decisions. In recent years, the field of radiomics, which involves the extraction and analysis of quantitative imaging features, has shown promise in improving management of pelvic cancers. The aim of this study was to evaluate the current application of radiomics in the management of anal cancer., Methods: A systematic search was conducted in Medline, EMBASE, and Web of Science databases. Inclusion criteria encompassed randomized and non-randomized trials investigating the use of radiomics to predict post-operative recurrence in anal cancer. Study quality was assessed using the QUADAS-2 and Radiomics Quality Score tools., Results: The systematic review identified a total of nine studies, with 589 patients examined. There were three main outcomes assessed in included studies: recurrence (6 studies), progression-free survival (2 studies), and prediction of human papillomavirus (HPV) status (1 study). Radiomics-based risk stratification models were found to provide valuable insights into treatment response and patient outcomes, with all developed signatures demonstrating at least modest accuracy (range: .68-1.0) in predicting their primary outcome., Conclusion: Radiomics has emerged as a promising tool in the management of anal cancer. It offers the potential for improved risk stratification, treatment planning, and response assessment, thereby guiding personalized therapeutic approaches., Competing Interests: Declaration of conflicting interestsThe author(s) declared no potential conflicts of interest with respect to the research, authorship, and/or publication of this article.

Purpose: To analyze tumor characteristics derived from pelvic magnetic resonance imaging (MRI) of patients with squamous cell carcinoma of the anus (SCCA) before and during chemoradiotherapy (CRT), and to compare the changes in these characteristics between scans of responders vs. nonresponders to CRT., Methods: We included 52 patients with a pelvic 3T MRI scan prior to CRT (baseline scan); 39 of these patients received an additional scan during week 2 of CRT (second scan). Volume, diameter, extramural tumor depth (EMTD), and external anal sphincter infiltration (EASI) of the tumor were assessed. Mean, kurtosis, skewness, standard deviation (SD), and entropy values were extracted from apparent diffusion coefficient (ADC) histograms. The main outcome was locoregional treatment failure. Correlations were evaluated with Wilcoxon's signed rank-sum test and Pearson's correlation coefficient, quantile regression, univariate logistic regression, and area under the ROC curve (AUC) analyses., Results: In isolated analyses of the baseline and second MRI scans, none of the characteristics were associated with outcome. Comparison between the scans showed significant changes in several characteristics: volume, diameter, EMTD, and ADC skewness decreased in the second scan, although the mean ADC increased. Small decreases in volume and diameter were associated with treatment failure, and these variables had the highest AUC values (0.73 and 0.76, respectively) among the analyzed characteristics., Conclusion: Changes in tumor volume and diameter in an early scan during CRT could represent easily assessable imaging-based biomarkers to eliminate the need for analysis of more complex MRI characteristics., (© 2023. The Author(s).)

Anal cancer incidence is significantly higher in people living with HIV as HIV increases the oncogenic potential of human papillomavirus. The incidence of anal cancer in the United States has recently increased, with diagnosis and treatment hampered by high loss-to-follow-up rates. Novel methods for the automated, real-time diagnosis of AIN 2+ could enable "see and treat" strategies, reducing loss-to-follow-up rates. A previous retrospective study demonstrated that the accuracy of a high-resolution microendoscope (HRME) coupled with a deep learning model was comparable to expert clinical impression for diagnosis of AIN 2+ (sensitivity 0.92 [P = 0.68] and specificity 0.60 [P = 0.48]). However, motion artifacts and noise led to many images failing quality control (17%). Here, we present a high frame rate HRME (HF-HRME) with improved image quality, deployed in the clinic alongside a deep learning model and evaluated prospectively for detection of AIN 2+ in real-time. The HF-HRME reduced the fraction of images failing quality control to 4.6% by employing a high frame rate camera that enhances contrast and limits motion artifacts. The HF-HRME outperformed the previous HRME (P < 0.001) and clinical impression (P < 0.0001) in the detection of histopathologically confirmed AIN 2+ with a sensitivity of 0.91 and specificity of 0.87., (© 2023. The Author(s).)

Positron emission tomography (PET) in the era of personalized medicine has a unique role in the management of oncological patients and offers several advantages over standard anatomical imaging. However, the role of molecular imaging in lower GI malignancies has historically been limited due to suboptimal anatomical evaluation on the accompanying CT, as well as significant physiological 18 F-flurodeoxyglucose (FDG) uptake in the bowel. In the last decade, technological advancements have made whole-body FDG-PET/MRI a feasible alternative to PET/CT and MRI for lower GI malignancies. PET/MRI combines the advantages of molecular imaging with excellent soft tissue contrast resolution. Hence, it constitutes a unique opportunity to improve the imaging of these cancers. FDG-PET/MRI has a potential role in initial diagnosis, assessment of local treatment response, and evaluation for metastatic disease. In this article, we review the recent literature on FDG-PET/MRI for colorectal and anal cancers; provide an example whole-body FDG-PET/MRI protocol; highlight potential interpretive pitfalls; and provide recommendations on particular clinical scenarios in which FDG-PET/MRI is likely to be most beneficial for these cancer types., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Objectives: A published tumour regression grade (TRG) score for squamous anal carcinoma treated with definitive chemoradiotherapy based on T2-weighted MRI yields a high proportion of indeterminate responses (TRG-3). We investigate whether the addition of diffusion-weighted imaging (DWI) improves tumour response assessment in the early post treatment period., Materials and Methods: This retrospective observational study included squamous anal carcinoma patients undergoing MRI before and within 3 months of completing chemoradiotherapy from 2009 to 2020. Four independent radiologists (1-20 years' experience) scored MRI studies using a 5-point TRG system (1 = complete response; 5 = no response) based on T2-weighted sequences alone, and then after a 12-week washout period, using a 5-point DWI-TRG system based on T2-weighted and DWI. Scoring confidence was recorded on a 5-point scale (1 = low; 5 = high) for each reading and compared using the Wilcoxon test. Indeterminate scores (TRG-3) from each reading session were compared using the McNemar test. Interobserver agreement was assessed using kappa statistics., Results: Eighty-five patients were included (mean age, 59 years ± 12 [SD]; 55 women). T2-weighted TRG-3 scores from all readers combined halved from 24% (82/340) to 12% (41/340) with DWI (p < 0.001). TRG-3 scores changed most frequently (41%, 34/82) to DWI-TRG-2 (excellent response). Complete tumour response was recorded clinically in 77/85 patients (91%). Scoring confidence increased using DWI (p < 0.001), with scores of 4 or 5 in 84% (287/340). Interobserver agreement remained fair to moderate (kappa range, 0.28-0.58)., Conclusion: DWI complements T2-weighted MRI by reducing the number of indeterminate tumour responses (TRG-3). DWI increases radiologist's scoring confidence., Clinical Relevance Statement: Diffusion-weighted imaging improves T2-weighted tumour response assessment in squamous anal cancer, halving the number of indeterminate responses in the early post treatment period, and increases radiologists' confidence., Key Points: Tumour response based on T2-weighted MRI is often indeterminate in squamous anal carcinoma. Diffusion-weighted imaging alongside T2-weighted MRI halved indeterminate tumour regression grade scores assigned by four radiologists from 24 to 12%. Scoring confidence of expert and non-expert radiologists increased with the inclusion of diffusion-weighted imaging., (© 2023. The Author(s).)

Purpose: To evaluate the variability of the 18F-FDG-PET/CT-based metabolic tumor volume (MTV) in anal cancers during fractionated chemoradiotherapy (CRT), and assess the impact of this variability on dosimetric accuracy in MTV-targeted dose painting., Methods: Eleven patients with anal squamous cell carcinoma who received fractionated chemoradiotherapy with curative intent were included. 18F-FDG PET/CT images were acquired at pre- and mid-treatment. Target volumes and organs at risk (OARs) were contoured manually on both image series. The MTV was generated from the PET images by thresholding. Treatment plans were retrospectively optimized for both image series using volumetric modulated arc therapy (VMAT). Standard plans prescribed 48.6 Gy, 54 Gy and 57.5 Gy in 27 fractions to elective regions, lymph node metastases and primary tumor, respectively. Dose painting plans included an extra dose level of 65 Gy to the MTV. Pre-treatment plans were transferred and re-calculated at mid-treatment basis., Results: MTV decreased from pre- to mid-treatment in 10 of the 11 patients. On average, 71 % of MTV mid overlapped with MTV pre . The median and mean doses to the MTV were robust against anatomical changes, but the transferred dose painting plans had lower D 98% values than the original and re-optimized plans. No major differences were found between standard and dose painting plans for OARs., Conclusions: Despite volumetric changes in the MTV, adequate dose coverage was observed in most dose painting plans. The findings indicate little or no need for adaptive dose painting at mid-treatment. Dose painting appears to be a safe treatment alternative with similar dose sparing of OARs., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

Anal cancer is a rare disease, but its incidence has been increasing steadily. Primary staging and assessment after chemoradiation therapy are commonly performed using MRI, which is considered to be the preferred imaging modality. CT and PET/CT are useful in evaluating lymph node metastases and distant metastatic disease. Anal squamous-cell carcinoma (ASCC) and rectal adenocarcinoma are typically indistinguishable on MRI, and a biopsy prior to imaging is necessary to accurately stage the tumor and determine the treatment approach. This review discusses the histology, MR technique, diagnosis, staging, and treatment of anal cancer, with a particular focus on the differences in TNM staging between anal and rectal carcinomas., Purpose: This review discusses the histology, MR technique, diagnosis, staging, and treatment of anal cancer, with a particular focus on the differences in TNM staging between anal squamous-cell carcinoma (ASCC) and rectal adenocarcinoma., Methods and Materials: To conduct this updated review, a comprehensive literature search was performed using prominent medical databases, including PubMed and Embase. The search was limited to articles published within the last 10 years (2013-2023) to ensure their relevance to the current state of knowledge., Inclusion Criteria: (1) articles that provided substantial information on the diagnostic techniques used for ASCC, mainly focusing on imaging, were included; (2) studies reporting on emerging technologies; (3) English-language articles., Exclusion Criteria: articles that did not meet the inclusion criteria, case reports, or articles with insufficient data. The primary outcome of this review is to assess the accuracy and efficacy of different diagnostic modalities, including CT, MRI, and PET, in diagnosing ASCC. The secondary outcomes are as follows: (1) to identify any advancements or innovations in diagnostic techniques for ASCC over the past decade; (2) to highlight the challenges and limitations of the diagnostic process., Results: ASCC is a rare disease; however, its incidence has been steadily increasing. Primary staging and assessment after chemoradiation therapy are commonly performed using MRI, which is considered to be the preferred imaging modality. CT and PET/CT are useful in evaluating lymph node metastases and distant metastatic disease., Conclusion: ASCC and rectal adenocarcinoma are the most common histological subtypes and are typically indistinguishable on MRI; therefore, a biopsy prior to imaging is necessary to stage the tumor accurately and determine the treatment approach.

Anal squamous cell carcinoma (ASCC) has a generally acceptable outlook in terms of survival. 18-fluorodeoxyglucose-positron emission tomography/computer tomography (FDG PET-CT) is not recommended for routine monitoring post-ASCC treatment. We examine herein if FDG PET-CT has a use in the prognostic evaluation of patients with ASCC, what FDG PET-CT metrics are of value and if a pre- or post-chemo/radiotherapy scan is more prognostic of outcomes. PubMed, EMBASE and Cochrane Central Registry of Controlled Trials were comprehensively searched until 3 May, 2023. A modified Newcastle Ottawa scale was used to assess for study bias. We present our systematic review alongside pooled hazard ratios (HR) for maximum standardised uptake values (SUV) as a predictor of overall survival (OS) and progression-free survival (PFS). Seven studies including 523 patients were included in our systematic review. Current evidence suggests that SUV maximum and median, metabolic tumour volume, total lesion glycolysis and complete and partial metabolic response may be prognostic when considering overall or progression-free survival (OS)/(PFS) along with local recurrence (LR). Pooled HR from two included studies indicate SUV max is prognostic of OS, HR 1.179, CI (1.039-1.338), P = 0.011 and PFS 1.176, CI (1.076-1.285), P < 0.01. FDG PET-CT may have a role to play in the prognostic evaluation of ASCC patients. Current evidence suggests post-treatment scanning may hold superior prognostic value at this time., (© 2023 Royal Australian and New Zealand College of Radiologists.)

The Society of Abdominal Radiology's Colorectal and Anal Cancer Disease-Focused Panel (DFP) first published a rectal cancer lexicon paper in 2019. Since that time, the DFP has published revised initial staging and restaging reporting templates, and a new SAR user guide to accompany the rectal MRI synoptic report (primary staging). This lexicon update summarizes interval developments, while conforming to the original lexicon 2019 format. Emphasis is placed on primary staging, treatment response, anatomic terminology, nodal staging, and the utility of specific sequences in the MRI protocol. A discussion of primary tumor staging reviews updates on tumor morphology and its clinical significance, T1 and T3 subclassifications and their clinical implications, T4a and T4b imaging findings/definitions, terminology updates on the use of MRF over CRM, and the conundrum of the external sphincter. A parallel section on treatment response reviews the clinical significance of near-complete response and introduces the lexicon of "regrowth" versus "recurrence". A review of relevant anatomy incorporates updated definitions and expert consensus of anatomic landmarks, including the NCCN's new definition of rectal upper margin and sigmoid take-off. A detailed review of nodal staging is also included, with attention to tumor location relative to the dentate line and locoregional lymph node designation, a new suggested size threshold for lateral lymph nodes and their indications for use, and imaging criteria used to differentiate tumor deposits from lymph nodes. Finally, new treatment terminologies such as organ preservation, TNT, TAMIS and watch-and-wait management are introduced. This 2023 version aims to serve as a concise set of up-to-date recommendations for radiologists, and discusses terminology, classification systems, MRI and clinical staging, and the evolving concepts in diagnosis and treatment of rectal cancer., (© 2023. This is a U.S. Government work and not under copyright protection in the US; foreign copyright protection may apply.)

Purpose: Different methods are available to identify haematopoietically active bone marrow (ActBM). However, their use can be challenging for radiotherapy routine treatments, since they require specific equipment and dedicated time. A machine learning (ML) approach, based on radiomic features as inputs to three different classifiers, was applied to computed tomography (CT) images to identify haematopoietically active bone marrow in anal cancer patients., Methods: A total of 40 patients was assigned to the construction set (training set + test set). Fluorine-18-Fluorodeoxyglucose Positron Emission Tomography ( 18 FDG-PET) images were used to detect the active part of the pelvic bone marrow (ActPBM) and stored as ground-truth for three subregions: iliac, lower pelvis and lumbosacral bone marrow (ActIBM, ActLPBM, ActLSBM). Three parameters were used for the correspondence analyses between 18 FDG-PET and ML classifiers: DICE index, Precision and Recall., Results: For the 40-patient cohort, median values [min; max] of the Dice index were 0.69 [0.20; 0.84], 0.76 [0.25; 0.89], and 0.36 [0.15; 0.67] for ActIBM, ActLSBM, and ActLPBM, respectively. The Precision/Recall (P/R) ratio median value for the ActLPBM structure was 0.59 [0.20; 1.84] (over segmentation), while for the other two subregions the P/R ratio median has values of 1.249 [0.43; 4.15] for ActIBM and 1.093 [0.24; 1.91] for ActLSBM (under segmentation)., Conclusion: A satisfactory degree of overlap compared to 18 FDG-PET was found for 2 out of the 3 subregions within pelvic bones. Further optimization and generalization of the process is required before clinical implementation., Competing Interests: Declaration of Competing Interest The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper., (Copyright © 2023 Associazione Italiana di Fisica Medica e Sanitaria. Published by Elsevier Ltd. All rights reserved.)

The role and method of image-based staging of anal cancer has evolved with the rapid development of newer imaging modalities and the need to address the rising incidence of this rare cancer. In 2014, the European Society of Medical Oncology mandated pelvic magnetic resonance imaging (MRI) for anal cancer and subsequently other societies such as the National Comprehensive Cancer Network followed suit with similar recommendations. Nevertheless, great variability exists from center to center and even within individual centers. Notably, this is in stark contrast to the imaging of the anatomically nearby rectal cancer. As participating team members for this malignancy, we embarked on a comprehensive literature review of anal cancer imaging to understand the relative merits of these new technologies which developed after computed tomography (CT), e.g., MRI and positron emission tomography/computed tomography (PET/CT). The results of this literature review helped to inform our next stage: questionnaire development regarding the imaging of anal cancer. Next, we distributed the questionnaire to members of the Society of Abdominal Radiology (SAR) Rectal and Anal Disease-Focused Panel, a group of abdominal radiologists with special interest, experience, and expertise in rectal and anal cancer, to provide expert radiologist opinion on the appropriate anal cancer imaging strategy. In our expert opinion survey, experts advocated the use of MRI in general (65% overall and 91-100% for primary staging clinical scenarios) and acknowledged the superiority of PET/CT for nodal assessment (52-56% agreement for using PET/CT in primary staging clinical scenarios compared to 30% for using MRI). We therefore support the use of MRI and PET and suggest further exploration of PET/MRI as an optimal combined evaluation. Our questionnaire responses emphasized the heterogeneity in imaging practice as performed at numerous academic cancer centers across the United States and underscore the need for further reconciliation and establishment of best imaging practice guidelines for optimized patient care in anal cancer., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Anal cancer is an uncommon malignancy. In addition to squamous cell carcinoma, there are a variety of other less common malignancies and benign pathologies that may afflict the anal canal, with which abdominal radiologists should be familiar. Abdominal radiologists should be familiar with the imaging features that can help distinguish different rare anal tumors beyond squamous cell carcinoma and that can aid in diagnosis therefore help steer management. This review discusses these uncommon pathologies with a focus on their imaging appearance, management, and prognosis., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Anal cancer treatment response assessment can be challenging with both magnetic resonance imaging (MRI) and clinical evaluation considered essential. MRI, in particular, has shown to be useful for the assessment of treatment response, the detection of recurrent disease in follow up and surveillance, and the evaluation of possible post-treatment complications as well as complications from the tumor itself. In this review, we focus on the role of imaging, mainly MRI, in anal cancer treatment response assessment. We also describe the treatment complications that can occur, and the imaging findings associated with those complications., (© 2023. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Background: To date, anal cancer patients are treated with radiotherapy to similar volumes despite a marked difference in risk profile based on tumor location and stage. A more individualized approach to delineation of the elective clinical target volume (CTVe) could potentially provide better oncological outcomes as well as improved quality of life. The aim of the present work was to establish Nordic Anal Cancer (NOAC) group guidelines for delineation of the CTVe in anal cancer. Methods: First, 12 radiation oncologists reviewed the literature in one of the following four areas: (1) previous delineation guidelines; (2) patterns of recurrence; (3) anatomical studies; (4) common iliac and para-aortic recurrences and delineation guidelines. Second, areas of controversy were identified and discussed with the aim of reaching consensus. Results: We present consensus-based recommendations for CTVe delineation in anal cancer regarding (a) which regions to include, and (b) how the regions should be delineated. Some of our recommendations deviate from current international guidelines. For instance, the posterolateral part of the inguinal region is excluded, decreasing the volume of irradiated normal tissue. For the external iliac region and the cranial border of the CTVe, we agreed on specifying two different recommendations, both considered acceptable. One of these recommendations is novel and risk-adapted; the external iliac region is omitted for low-risk patients, and several different cranial borders are used depending on the individual level of risk. Conclusion: We present NOAC consensus guidelines for delineation of the CTVe in anal cancer, including a risk-adapted strategy.

Purpose: To optimize inguinal nodal clinical target volume (CTV) delineation based on analysis of the anatomical locations and embryonic development of normal and metastatic inguinal lymph nodes (ILNs) in patients with pelvic malignant tumors, including cervical, vaginal, vulvar, and anal tumors., Materials and Methods: One hundred and eighty-one patients with pelvic malignancies and 415 involved ILNs treated with intensity-modulated radiation therapy were selected. First, the inguinal nodal CTV was divided into three fields as follows: I, horizontal superficial inguinal field; II, vertical superficial inguinal field; and III, deep inguinal field. Initial CTV delineation of each field was based on analysis of the anatomical locations and embryonic development of normal ILNs. Subsequently, the positions of metastatic ILNs relative to the proper anatomical landmarks or vessels were determined to optimally delineate the final ILN CTV contours. Eighty percent of the data acquired (n = 145) were used as test data for optimization and analysis, the remaining 20% (n = 36) were used for delineation validation., Results: In total, 252 positive ILNs in 103 cervical cancer patients, 94 positive ILNs in 41 vulvar cancer patients, 8 positive ILNs in 3 vaginal cancer patients, and 61 positive ILNs in 34 anal cancer patients were enrolled. Detailed target volume contouring guidelines for the three divisions were determined on images. All positive ILNs from the remaining 20% patients were located in the CTV boundaries delineated based on analysis of 80% of the data acquired. Importantly, the final inguinal nodal CTV field determined using our method was substantially smaller than defined by existing atlases, and the femoral vessels were excluded in the delineation., Conclusions: This study provided anatomical, embryonic, surgical, and statistical evidence to facilitate ILN CTV delineation in radiotherapy planning for patients with pelvic malignancies., (Copyright © 2023 Elsevier B.V. All rights reserved.)

The paper deals with the evaluation of the performance of an existing and previously validated CT based radiomic signature, developed in oropharyngeal cancer to predict human papillomavirus (HPV) status, in the context of anal cancer. For the validation in anal cancer, a dataset of 59 patients coming from two different centers was collected. The primary endpoint was HPV status according to p16 immunohistochemistry. Predefined statistical tests were performed to evaluate the performance of the model. The AUC obtained here in anal cancer is 0.68 [95% CI (0.32-1.00)] with F1 score of 0.78. This signature is TRIPOD level 4 (57%) with an RQS of 61%. This study provides proof of concept that this radiomic signature has the potential to identify a clinically relevant molecular phenotype (i.e., the HPV-ness) across multiple cancers and demonstrates potential for this radiomic signature as a CT imaging biomarker of p16 status., (© 2023. The Author(s).)

The main histopathological types of anal fistula cancers are mucinous adenocarcinoma and tubular adenocarcinoma. The purpose of this study was to investigate the utility of the apparent diffusion coefficient (ADC) value in magnetic resonance imaging (MRI) to determine the histopathological type of an anal fistula cancer, and to investigate the relationship between ADC values and histopathological type (mucinous type or tubular carcinoma), clinical information, and surgical findings. We retrospectively identified 69 patients diagnosed with anal fistula cancer at our hospital from January 2013 to December 2021. Among them, we selected the patients diagnosed using the same 1.5-T MRI machine, underwent surgery, and a pathological sample was obtained during the operation. Finally, these 25 patients were selected for the analysis since they underwent the imaging scan using the same MRI machine. The ADC value was compared between mucinous and tubular adenocarcinomas, and between tumors at the Tis-T1-T2 and T3-T4 stages. Finally, 25 patients were selected. The mean age of the 25 patients included in the analysis was 60.8 ± 13.3 years and all were males. The median ADC of anal fistula cancers was 1.97 × 10-3 mm2/s for mucinous adenocarcinomas and 1.36 × 10-3 mm2/s for tubular adenocarcinomas; this difference was statistically significant (P < .01). Furthermore, the median ADC was 1.62 × 10-3 mm2/s for tumors in Tis-T1-T2 stages and 2.01 × 10-3 mm2/s for T3-T4 tumors (P = .02). The ADC value in MR images may predict the histopathological type and depth of anal fistula cancers. Also, the different ADC values between Tis-T1-T2 and T3-T4 tumors could help predict the classification of progression., Competing Interests: The authors have no funding and conflicts of interest to disclose., (Copyright © 2023 the Author(s). Published by Wolters Kluwer Health, Inc.)

Malignant anorectal melanoma is an extremely rare cause of rectal neoplasia, accounting for less than 1% of all melanomas and about 4% of all malignant colorectal neoplasms. We present the endoscopic and pathological images of a case in our clinical practice.

Introduction: Anal cancer (AC) is 18 F-FDG-PET avid and has been used to evaluate treatment response several months after chemoradiotherapy. This pilot study aimed to assess the utility of semi-automated contouring methods and quantitative measures of treatment response using 18 F-FDG-PET imaging at the early time point of 1-month post-chemoradiotherapy., Methods: Eleven patients with AC referred for chemoradiotherapy were prospectively enrolled into this study, with 10 meeting eligibility requirements. 18 F-FDG-PET imaging was obtained pre-chemoradiotherapy (TP1), and then 1-month (TP2), 3-6 months (TP3) and 9-12 months (TP4) post-chemoradiotherapy. Manual and semi-automated (Threshold) contouring methods were used to define the primary tumour on all 18 F-FDG-PET images. Resultant contours from each method were interrogated using quantitative measures, including volume, response index (RI), total lesion glycolysis (TLG), SUV max , SUV median and SUV mean . Response was assessed quantitatively as reductions in these measures and also qualitatively against established criteria., Results: Nine patients were qualitatively classified as complete metabolic responders at TP2 and all 10 at TP3. All quantitative measures demonstrated significant (P < 0.05) reductions at TP2 for both Manual and Threshold methods. All reduced further at TP3 and again at TP4 for Threshold methods. TLG showed the highest reduction at all post-chemoradiotherapy time points and classified the most responders for each method at each time point. All patients are recurrence-free at minimum 4-year follow-up., Conclusion: Based on our small sample size, semi-automated methods of disease definition using 18 F-FDG-PET imaging are feasible and appear to facilitate quantitative response classification of AC as early as 1-month post-chemoradiotherapy. Early identification of treatment response may potentially improve disease management., (© 2022 The Authors. Journal of Medical Radiation Sciences published by John Wiley & Sons Australia, Ltd on behalf of Australian Society of Medical Imaging and Radiation Therapy and New Zealand Institute of Medical Radiation Technology.)

Background: High-resolution anoscopy (HRA) is the gold standard for detecting anal squamous cell cancer (ASCC) precursors. Although it is superior to other diagnostic methods, particularly cytology, the visual identification of areas suspected of having high-grade squamous intraepithelial lesions remains difficult. Convolutional neural networks (CNNs) have shown great potential for assessing endoscopic images. The aim of the present study was to develop a CNN-based system for automatic detection and differentiation of HSIL versus LSIL in HRA images., Methods: A CNN was developed based on 78 HRA exams from a total of 71 patients who underwent HRA at a single high-volume center (GH Paris Saint-Joseph, Paris, France) between January 2021 and January 2022. A total of 5026 images were included, 1517 images containing HSIL and 3509 LSIL. A training dataset comprising 90% of the total pool of images was defined for the development of the network. The performance of the CNN was evaluated using an independent testing dataset comprising the remaining 10%. The sensitivity, specificity, accuracy, positive and negative predictive values, and area under the curve (AUC) were calculated., Results: The algorithm was optimized for the automatic detection of HSIL and its differentiation from LSIL. Our model had an overall accuracy of 90.3%. The CNN had sensitivity, specificity, positive and negative predictive values of 91.4%, 89.7%, 80.9%, and 95.6%, respectively. The area under the curve was 0.97., Conclusions: The CNN architecture for application to HRA accurately detected precursors of squamous anal cancer. Further development and implementation of these tools in clinical practice may significantly modify the management of these patients., (© 2022. Springer Nature Switzerland AG.)

Objective: To review existing structured MRI reports for primary staging of rectal cancer and create a new, freely available structured report based on multidisciplinary expert opinion and literature review., Methods: Twenty abdominal imaging experts from the Society of Abdominal Radiology (SAR)'s Disease Focused Panel (DFP) on Rectal and Anal Cancer completed a questionnaire and participated in a subsequent consensus meeting based on the RAND-UCLA Appropriateness Method. Twenty-two items were classified via a group survey as "appropriate" or "inappropriate" (defined by ≥ 70% consensus), or "needs group discussion" (defined by < 70% consensus). Certain items were also discussed with multidisciplinary team members from colorectal surgery, oncology and pathology., Results: After completion of the questionnaire, 16 (72%) items required further discussion (< 70% consensus). Following group discussion, consensus was achieved for 21 (95%) of the items. Based on the consensus meeting, a revised structured report was developed. The most significant modifications included (1) Exclusion of the T2/early T3 category; (2) Replacement of the term "circumferential resection margin (CRM)" with "mesorectal fascia (MRF)"; (3) A revised definition of "mucinous content"; (4) Creation of two distinct categories for suspicious lymph nodes (LNs) and tumor deposits; and (5) Classification of suspicious extra-mesorectal LNs by anatomic location., Conclusion: The SAR DFP on Rectal and Anal Cancer recommends using this newly updated reporting template for primary MRI staging of rectal cancer., (© 2022. The Author(s), under exclusive licence to Springer Science+Business Media, LLC, part of Springer Nature.)

Competing Interests: The authors declare that they have no conflict of interest.

Objectives: To assess the effectiveness of fluorine-18 fluorodeoxyglucose (FDG) positron-emission tomography-computed tomography (PET-CT) and magnetic resonance imaging (MRI) for response assessment post curative-intent chemoradiotherapy (CRT) in anal squamous cell carcinoma (ASCC)., Methods: Consecutive ASCC patients treated with curative-intent CRT at a single centre between January 2018 and April 2020 were retrospectively identified. Clinical meta-data including progression-free survival (PFS) and overall survival (OS) outcomes were collated. Three radiologists evaluated PET-CT and MRI using qualitative response assessment criteria and agreed in consensus. Two-proportion z test was used to compare diagnostic performance metrics (sensitivity, specificity, positive predictive value (PPV), negative predictive value (NPV), accuracy). Kaplan-Meier analysis (Mantel-Cox log-rank) was performed., Results: MRI (accuracy 76%, PPV 44.8%, NPV 95.7%) and PET-CT (accuracy 69.3%, PPV 36.7%, NPV 91.1%) performance metrics were similar; when combined, there were statistically significant improvements (accuracy 94.7%, PPV 78.9%, NPV 100%). Kaplan-Meier analysis demonstrated significant differences in PFS between responders and non-responders at PET-CT (p = 0.007), MRI (p = 0.005), and consensus evaluation (p < 0.001). Cox regression analysis of PFS demonstrated a lower hazard ratio (HR) and narrower 95% confidence intervals for consensus findings (HR = 0.093, p < 0.001). Seventy-five patients, of which 52 (69.3%) were females, with median follow-up of 17.8 months (range 5-32.6) were included. Fifteen of the 75 (20%) had persistent anorectal and/or nodal disease after CRT. Three patients died, median time to death 6.2 months (range 5-18.3)., Conclusion: Combined PET-CT and MRI response assessment post-CRT better predicts subsequent outcome than either modality alone. This could have valuable clinical benefits by guiding personalised risk-adapted patient follow-up., Key Points: • MRI and PET-CT performance metrics for assessing response following chemoradiotherapy (CRT) in patients with anal squamous cell carcinoma (ASCC) were similar. • Combined MRI and PET-CT treatment response assessment 3 months after CRT in patients with ASCC was demonstrated to be superior to either modality alone. • A combined MRI and PET-CT assessment 3 months after CRT in patients with ASCC has the potential to improve accuracy and guide optimal patient management with a greater ability to predict outcome than either modality alone., (© 2022. The Author(s).)

Basal cell carcinoma (BCC) is a common skin malignancy and usually occurs in sun-exposed areas like the head and neck. Occurrence in the perianal area is rare, accounting for only 0.08% of all BCC, and 0.2% of anorectal malignancies.We present a case of a hypertensive woman in her 60s who had a 1-year history of a gradually enlarging mass on the left perianal region. Initial biopsy revealed a carcinoma with basaloid features and was confirmed on immunohistochemistry to be nodular BCC. Proctoscopy showed no intraluminal involvement. Contrast-enhanced chest and abdominal CT scans revealed no nodal or distant metastasis. MRI showed a 7.5 mm fat plane between the mass and the external sphincter muscles, projecting adequate surgical margins.A wide excision with at least 4 mm margins was performed. Reconstruction of the resulting defect was performed with a local random cutaneous flap., Competing Interests: Competing interests: None declared., (© BMJ Publishing Group Limited 2022. No commercial re-use. See rights and permissions. Published by BMJ.)

We present the update of the recommendations of the French society for radiation oncology on external radiotherapy and brachytherapy of anal canal carcinoma. The following guidelines are presented: indications, treatment procedure, as well as dose and dose-constraints objectives, immediate postoperative management, post-treatment evaluation, and long-term follow-up., (Copyright © 2021 Société française de radiothérapie oncologique (SFRO). Published by Elsevier Masson SAS. All rights reserved.)

Background: Accurate target volume delineation is a prerequisite for high-precision radiotherapy. However, manual delineation is resource-demanding and prone to interobserver variation. An automatic delineation approach could potentially save time and increase delineation consistency. In this study, the applicability of deep learning for fully automatic delineation of the gross tumour volume (GTV) in patients with anal squamous cell carcinoma (ASCC) was evaluated for the first time. An extensive comparison of the effects single modality and multimodality combinations of computed tomography (CT), positron emission tomography (PET), and magnetic resonance imaging (MRI) have on automatic delineation quality was conducted., Material and Methods: 18F-fluorodeoxyglucose PET/CT and contrast-enhanced CT (ceCT) images were collected for 86 patients with ASCC. A subset of 36 patients also underwent a study-specific 3T MRI examination including T2- and diffusion-weighted imaging. The resulting two datasets were analysed separately. A two-dimensional U-Net convolutional neural network (CNN) was trained to delineate the GTV in axial image slices based on single or multimodality image input. Manual GTV delineations constituted the ground truth for CNN model training and evaluation. Models were evaluated using the Dice similarity coefficient (Dice) and surface distance metrics computed from five-fold cross-validation., Results: CNN-generated automatic delineations demonstrated good agreement with the ground truth, resulting in mean Dice scores of 0.65-0.76 and 0.74-0.83 for the 86 and 36-patient datasets, respectively. For both datasets, the highest mean Dice scores were obtained using a multimodal combination of PET and ceCT (0.76-0.83). However, models based on single modality ceCT performed comparably well (0.74-0.81). T2W-only models performed acceptably but were somewhat inferior to the PET/ceCT and ceCT-based models., Conclusion: CNNs provided high-quality automatic GTV delineations for both single and multimodality image input, indicating that deep learning may prove a versatile tool for target volume delineation in future patients with ASCC.

Lower rectal and anal cancers are distinct from neoplasms involving rest of the rectum. These are relatively difficult to manage owing to important relationships with the sphincter muscles. Involvement of the latter portends a poorer prognosis and increased chance of recurrence. Lymphatic drainage of these tumours is into the systemic circulation and the exact set of lymph nodes involved depends on the precise location of the tumour. The role of imaging includes assessment of local invasion, infiltration of adjacent pelvic organs, assessment of locoregional lymphatic spread and metastasis, post-chemoradiation restaging as well as post-treatment surveillance., (Copyright © 2021 The Royal College of Radiologists. Published by Elsevier Ltd. All rights reserved.)

Competing Interests: Competing interests: None declared.

We evaluated the inter-physician variability in the target contouring of the radiotherapy for anal squamous cell carcinoma (ASCC). Clinical target volume (CTV) of three patients diagnosed with ASCC was delineated by seven experienced radiation oncologists from multi-institution. These patients were staged as pT1N1a, cT2N0, and cT4N1a, respectively, according to 8 th edition of the American Joint Committee on Cancer staging system. Expert agreement was quantified using an expectation maximization algorithm for Simultaneous Truth and Performance Level Estimation (STAPLE). The maximum distance from the boundaries of the STAPLE generated volume with confidence level of 80% to those of the contour of each CTV in 6 directions was compared. CTV of pelvis which includes primary tumor, perirectal tissue and internal/external iliac lymph node (LN) area (CTV-pelvis) and CTV of inguinal area (CTV-inguinal) were obtained from the seven radiation oncologists. One radiation oncologist did not contain inguinal LN area in the treatment target volume of patient 2 (cT2N0 stage). CTV-inguinal displayed moderate agreement for each patient (overall kappa 0.58, 0.54 and 0.6, respectively), whereas CTV-pelvis showed substantial agreement (overall kappa 0.66, 0.68 and 0.64, respectively). Largest variation among each contour was shown in the inferior margin of the CTV-inguinal. For CTV-pelvis, anterior and superior margin showed the biggest variation. Overall, moderate to substantial agreement was shown for CTV delineation. However, large variations in the anterior and cranial boarder of the CTV-pelvis and the caudal margin of the CTV-inguinal suggest that further studies are needed to establish a clearer target volume delineation guideline.

Aims: The use of diffusion-weighted magnetic resonance imaging (DW-MRI) as a prognostic marker of treatment response would enable early individualisation of treatment. We aimed to quantify the changes in mean apparent diffusion coefficient (ΔADC mean ) between a DW-MRI at diagnosis and on fraction 8-10 of chemoradiotherapy (CRT) as a biomarker for cellularity, and correlate these with anal squamous cell carcinoma recurrence., Materials and Methods: This prospective study recruited patients with localised anal cancer between October 2014 and November 2017. DW-MRI was carried out at diagnosis and after fraction 8-10 of radical CRT. A region of interest was delineated for all primary tumours and any lymph nodes >2 cm on high-resolution T 2 -weighted images and propagated to the ADC map. Routine clinical follow-up was collected from Nation Health Service electronic systems., Results: Twenty-three of 29 recruited patients underwent paired DW-MRI scans. Twenty-six regions of interest were delineated among the 23 evaluable patients. The median (range) tumour volume was 13.6 cm 3 (2.8-84.9 cm 3 ). Ten of 23 patients had lesions with ΔADC mean ≤ 20%. With a median follow-up of 41.2 months, four patients either failed to have a complete response to CRT or subsequently relapsed. Three of four patients with disease relapse had lesions demonstrating ΔADC mean <20%, the other patient with persistent disease had ΔADC mean of 20.3%., Conclusions: We demonstrated a potential correlation between patients with ΔADC mean <20% and disease relapse. Further investigation of the prognostic merit of DW-MRI change is needed in larger, prospective cohorts., (Crown Copyright © 2020. Published by Elsevier Ltd. All rights reserved.)

Background: The primary aim was to test the hypothesis that deriving pre-treatment 3D magnetic resonance tumour volume (mrTV) quantification improves performance characteristics for the prediction of loco-regional failure compared with standard maximal tumour diameter (1D) assessment in patients with squamous cell carcinoma of the anus undergoing chemoradiotherapy., Methods: We performed an early evaluation case-control study at two UK centres (2007-2014) in 39 patients with loco-regional failure (cases), and 41 patients disease-free at 3 years (controls). mrTV was determined using the summation of areas method (Vol sum ). Reproducibility was assessed using intraclass concordance correlation (ICC) and Bland-Altman limits of agreements. We derived receiver operating curves using logistic regression models and expressed accuracy as area under the curve (ROC AUC )., Results: The median time per patient for Vol sum quantification was 7.00 (inter-quartile range, IQR: 0.57-12.48) minutes. Intra and inter-observer reproducibilities were generally good (ICCs from 0.79 to 0.89) but with wide limits of agreement (intra-observer: - 28 to 31%; inter-observer: - 28 to 46%). Median mrTVs were greater for cases (32.6 IQR: 21.5-53.1 cm 3 ) than controls (9.9 IQR: 5.7-18.1 cm 3 , p < 0.0001). The ROC AUC for mrT-size predicting loco-regional failure was 0.74 (95% CI: 0.63-0.85) improving to 0.82 (95% CI: 0.72-0.92) when replaced with mrTV (test for ROC differences, p = 0.024)., Conclusion: Preliminary results suggest that the replacement of mrTV for mrT-size improves prediction of loco-regional failure after chemoradiotherapy for squamous cell carcinoma of the anus. However, mrTV calculation is time consuming and variation in its reproducibility are drawbacks with the current technology.

Purpose: We aimed to evaluate the accuracy of metabolic parameters, calculated on pretreatment positron emission computed tomography (PET/CT) with fluorodeoxyglucose (F-FDG), for predicting complete response to chemoradiotherapy (CRT) of patients affected by squamous cell anal carcinoma (SCAC)., Patients and Methods: Clinical records of 20 patients affected by SCAC and treated with CRT were retrospectively evaluated. F-FDG PET/CT was performed at time 0 (baseline) and time 1 (12 weeks after CRT). The following parameters were extracted from PET at time 0: standardized uptake values (SUVmax and SUVmean), metabolic tumor volume (MTV) and total lesion glycolysis (TLG). Response was assessed according to PET response criteria in solid tumors and classified as complete metabolic response (CMR), partial metabolic response (PMR) and progressive metabolic disease (PMD). Receiver operating characteristic analysis was performed to analyze the predictive value of each PET-derived parameter on CMR., Results: Sixteen patients were finally enrolled. All presented increased F-FDG uptake in the primary tumor and 11 (68.7%) also showed metastatic lymph nodes. At PET/CT performed at time 1, 11 subjects (68.7%) presented CMR, three (18.7%) had PMR and the remaining two (12.5%) showed PMD (i.e. hepatic metastases). Among baseline PET-derived parameters, both MTV and TLG efficiently predicted response to CRT with an area under the curve of 0.9 (cutoff 62.3 cm, sensitivity 80%, specificity 100%, P = <0.0001) and 0.87 (cutoff 654.1 g, sensitivity 80%, specificity 100%, P = 0.004), respectively., Conclusion: Among PET-derived parameters, both MTV and TLG presented a high predictive value on subjects' outcome after CRT.