Search

International audience; Prostate cancer (PCa) pelvic radiotherapy fields are defined by guidelines that do not consider individual variations in lymphatic drainage. We examined the feasibility of personalized sentinel lymph node (SLN)-based pelvic irradiation in PCa. Among a SLN study of 202 patients, we retrospectively selected 57 patients with a high risk of lymph node involvement. Each single SLN clinical target volume (CTV) was individually segmented and pelvic CTVs were contoured according to Radiation Therapy Oncology Group (RTOG) guidelines. We simulated a radiotherapy plan delivering 46 Gy and calculated the dose received by each SLN. Among a total of 332 abdominal SLNs, 305 pelvic SLNs (beyond the aortic bifurcation) were contoured (mean 5.4/patient). Based on standard guidelines, CTV missed 67 SLNs (22%), mostly at the common iliac level (40 SLNs). The mean distance between iliac vessels and the SLN was 11mm, and despite a 15mm margin around the iliac vessels, 9% of SLNs were not encompassed by the CTV. Moreover, 42 SLNs (63%) did not receive 95% of the prescribed dose. Despite a consensus on contouring guidelines, a significant proportion of SLNs were not included in the pelvic CTV and did not receive the prescribed dose. A tailored approach based on individual SLN detection would avoid underdosing pelvic lymph nodes that potentially contain tumor cells.

International audience; BACKGROUND:In this retrospective study, we investigated the impact of 68 Ga-PSMA-11 PET-CT (PSMA PET-CT) upon the treatment plan and therapeutic response obtained for Prostate Cancer (PCa) patients presenting an occult biochemical recurrence.METHODS:Forty-two patients with previously negative or doubtful 18F-Choline (FCH) were enrolled. PET images were recorded 1 h after injection of tracer. Only a few months after treatment ended, a PSA assay was requested to evaluate the therapeutic efficacy of the treatment based on PSMA results.RESULTS:PSMA-positive lesions were detected in 34/42 (80.9%) patients. Detection rates were 85.7% and 89.3% for serum PSA levels lower than 2 ng/mL, and >2 ng/mL, respectively. One hundred seventy-three lesions were detected: 132/173 in lymph nodes (76.3%), 22/173 as metastatic sites (bone or lung) (12.7%), and 19/173 in the prostate bed (10.9%). As a result of the PSMA PET-CT, therapeutic management changed in 31/42 patients (73.8%). With a follow-up of 4.9 ± 2.27 months, 32/42 (76.2%) PSA assays after treatment guided by PSMA PET-CT were collected. For 37.5% (12/32) of patients, the serum PSA level was lower than 0.2 ng/mL and a PSA decrease of over 50% in 8 (25.0%) other patients were obtained.CONCLUSION:Performing a PSMA PET-CT when FCH PET-CT was doubtful or negative allows the recurrence localization in more 80% of patients and this had a major clinical impact, as it resulted in treatment change in more than 70% of patients as well as a significant decrease in PSA levels in more than 60% of them.

// Vincent Fleury 1 , Ludovic Ferrer 2, 4 , Mathilde Colombie 1 , Daniela Rusu 1 , Maelle Le Thiec 1 , Francoise Kraeber-Bodere 1, 2 , Loic Campion 2, 3 and Caroline Rousseau 1, 2 1 Nuclear Medicine Unit, ICO Cancer Center, Saint Herblain, France 2 Nantes-Angers Cancer Research Center, INSERM U892, CNRS UMR 6299, University of Nantes, Nantes, France 3 Biometrics Unit, ICO Gauducheau Cancer Center, Saint Herblain, France 4 Medical Physics Unit, ICO Cancer Center, Saint Herblain, France Correspondence to: Vincent Fleury, email: vfleury245@gmail.com Keywords: SPECT/CT; bone scan; bone metastases; bone index; prostate cancer Received: March 29, 2018 Accepted: July 18, 2018 Published: August 03, 2018 ABSTRACT Propose: The aim of our study was to evaluate the potential benefit of a systematic trunk SPECT/CT associated with a Planar Bone Scan (PBS) in breast cancer (BC) and prostate cancer (PCa) patients at initial staging or recurrence. Results: In 328 patients, sensitivities and specificities were between 74.4–93% and 78.8–97.5% for PBS and 97.7–100% and 96.8–98.6% for SPECT/CT respectively. PBS was considered equivocal for 67 compared to only 6 patients for trunk SPECT/CT. Regardless of “optimistic” or “pessimistic” analysis of equivocal trunk SPECT/CT lesions, the trunk SPECT/CT was almost perfect, allowing to rely on this result for excluding metastatic disease which was corroborated by ROC curve analysis. The trunk SPECT/CT allowed downstaging for 62 patients (19%) and upstaging for 11 patients. Materials and Methods: PBS and a trunk SPECT/CT were systematically performed in all patients. Independent review of PBS and trunk SPECT/CT was performed for each patient and an abnormality interpretative score (Sc) with 3 levels was built: Sc 1: metastatic or probably metastatic pattern, Sc 2: equivocal pattern, Sc 3: benign or probably benign pattern or no abnormality. The bone pattern status was defined by at least 1 year follow-up. The clinical impact was evaluated in terms of down and upstaging in patient analysis. Conclusions: Trunk SPECT/CT improves the performance of PBS in BC and PCa assessments and results in improvements in both the detection performance of bone metastases as well as a better characterization of equivocal lesions.

International audience; Introduction: Medical research in PET/CT diagnosis involving new gallium-68 radiolabelled pharmaceuticals is steadily rising in the last years thanks to the combined improvement of both radionuclide production and radiolabelling. Publications demonstrate benefits for the patient but few studies evaluate the occupational dosimetric impact when use the gallium-68 in routine, in terms of effective and equivalent dose. Subjects & Methods: In this study, extremities, crystallin and whole body exposure are evaluated for three technologists when use of the gallium-68 radiolabelling with DOTATOC peptide (10 runs) requiring handmade steps and PSMA-11 peptide (5 runs) that is an automated process. Electronic dosimeter ED3 (APVL) is used to access to instantaneous dose-rate that can be afterward related to steps of handling. OSL pellets (LANDAUER) are used to measure the cumulative dose. Dosimeters are placed on fingers, protection eyeglass and chest. During the production runs, we separate radiolabelling phase from injection handmade phase to the patient (150 MBq/patient). The annual equivalent and effective doses are extrapolated on a mean of 2.5 patients per day during 52 weeks of 5 days with 68Ga-PSMA-11 or 68Ga-DOTATOC lonely. Results: The measurements show high exposures heterogeneity, confirmed with ED3 measurements that present high punctual peaks during the production runs. For 68Ga-PSMA-11, the median equivalent dose to extremities, per production run and per syringe, is 228 μSv [208; 493] and, at the injection time, the median equivalent dose to extremities per syringe is 212 μSv [188; 278]. For 68Ga-DOTATOC, the median equivalent dose to extremities, per production run and per syringe, is 315 μSv [28; 875] and, at the injection time, the median equivalent dose to extremities per syringe is 493 μSv [111; 1225]. The extrapolated annual equivalent dose to extremities lead to 288 mSv [257; 501] and 525 mSv [90; 1365], respectively for 68Ga-PSMA-11 and 68Ga-DOTATOC. The extrapolated annual equivalent dose to crystallin lead to 6,5 mSv [4,9; 11,7] and 1,3 mSv [background; 113,1], respectively for 68Ga-PSMA-11 and 68Ga-DOTATOC. The extrapolated annual effective dose lead to 1,3 mSv [background; 16,9] and 1,3 mSv [background; 53,3], respectively for 68Ga-PSMA-11 and 68Ga-DOTATOC. Conclusion: This study highlights that the use in routine of radiolabelled gallium-68 could lead to significant equivalent doses for technologist, especially since the protocol is not automated. This advocates strongly for a specific attention when routine use of a new radiopharmaceuticals, particularly on radiation optimisation of radiolabelling protocol and injection phase, also on high practical training of technologist.