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Purpose: This study aimed to analyze treatment outcomes and prognostic markers, including immune and inflammatory factors, of postoperative radiation therapy (RT) administered to patients with cholangiocarcinoma (CCA).Methods: We retrospectively selected 59 patients with CCA who underwent surgery and postoperative RT with curative intent from 2004 to 2019. Patients received external irradiation (50 Gy in 25 fractions) using three-dimensional RT. Overall survival (OS), cause-specific survival (CSS), progression-free survival (PFS), and locoregional control (LRC) rates of initial RT were assessed using the Kaplan–Meier method. Univariate and multivariate Cox proportional-hazards regression models were used to identify prognostic factors. We analyzed prognostic factors of inflammation, such as pre-RT platelet count, hemoglobin, lymphocyte count ratio (LCR) of the leukocyte count, platelet-to-lymphocyte ratio (PLR), and neutrophil-to-lymphocyte ratio (NLR).Results: Tumor stages were distributed as follows: I (n = 8), II (n = 25), III (n = 15), and IVA (n = 11). The median follow-up was 24 months. Two-year OS, CSS, PFS, and LRC rates were 59.5%, 62.0%, 40.1%, and 66.7%, respectively. Univariate analysis revealed that lower LCR was significantly associated with shorter PFS (P = 0.0446, hazard ratio (HR): 1.90, 95%, confidence interval (CI): 1.02–3.58). There was no significant difference between the median baseline values of PLR and NLR; and age ≥75, positive regional lymph node metastases (N+), and chemotherapy after RT were significantly associated with poor OS. Multivariate analysis revealed a significant association of N+ with OS, PFS and CSS and that lower LCR was significantly associated with PFS (HR: 0.481, CI: 0.252–0.905, p=0.0234). Among late toxicity events, two patients (3.38%) were suspected with therapy-related liver toxicity.Conclusions: LCR before RT was a prognostic factor for postoperative radiation therapy of patients with CCA.

Background/Aim: To evaluate the preventive effects of regional lymph node irradiation on lymph node recurrence in esophageal cancer (EC). Patients and Methods: The study included 289 patients who received definitive radiotherapy for EC. The regional lymph node area of group 1 was determined as the area with the highest probability of lymph node metastasis and group 2 was determined as the area with the next highest probability of lymph node metastasis depending on the primary site of EC. Results: The patients in whom group 2 was completely included in the irradiated field had a significantly lower rate of recurrence of regional lymph node metastasis than those in whom group 2 was not or insufficiently included (p=0.0337). There was no significant difference in overall survival (p=0.4627) or disease-specific survival (p=0.6174) between the two groups. Conclusion: Regional lymph node irradiation did not have survival-prolonging effects but significantly reduced regional lymph node recurrence.

Purpose Peptide receptor radionuclide therapy (PRRT) with 177Lu-DOTA0-Tyr3-octreotate (177Lu-DOTATATE) is one of the most reliable treatments for unresectable, progressive neuroendocrine tumors (NETs) with somatostatin receptor expression. We have, for the first time, reported the results of the tolerability, safety, pharmacokinetics, dosimetry, and efficacy of this treatment for Japanese patients with NET. Methods Patients with unresectable, somatostatin receptor scintigraphy (SRS)-positive NETs were enrolled in this phase I clinical trial. They were treated with 29.6 GBq of 177Lu-DOTATATE (four doses of 7.4 GBq) combined with amino acid solution infusion plus octreotide long-acting release (LAR) 30 mg. The primary objective of this study was to evaluate the tolerability, safety, pharmacokinetics, and dosimetry of a single administration of this treatment in patients with SRS-positive NETs. Results Six Japanese patients (three men and three women; mean age 61.5 years; range 50–70 years) with SRS-positive unresectable NETs were recruited. 177Lu-DOTATATE was eliminated from the blood in a two-phase manner. Cumulative urinary excretion of radioactivity was 60.1% (range 49.0%–69.8%) within the initial 6 h. The cumulative renal absorbed dose for 29.6 GBq of 177Lu-DOTATATE was 16.8 Gy (range 12.0–21.2 Gy), and the biological effective dose was 17.0 Gy (range 12.2–21.5 Gy). Administration of 177Lu-DOTATATE was well tolerated, with no dose-limiting toxicities. Grade 3 lymphopenia occurred in two (33.3%) cases, but there were no other severe toxicities. Four patients achieved partial response (objective response rate, 66.7%), one patient had stable disease, and one patient had progressive disease. Conclusion PRRT with 177Lu-DOTATATE was well-tolerated and showed good outcomes in Japanese patients with unresectable NETs. Peptide receptor radionuclide therapy, 177Lu-DOTA0-Tyr3-octreotate .

Peptide receptor radionuclide therapy(PRRT)is a pioneer drug in the rapid development of radio-theranostics, and a paradigm-shifting approach to treat neuroendocrine tumor( NET). The NETTER-1 trial for NETs of the midgut is currently the only global phase Ⅲ prospective clinical trial demonstrating the efficacy and safety of PRRT. In Japan, phase Ⅰ and Ⅰ/Ⅱ trials for lung and gastroenteropancreatic NETs were also conducted, and regulatory approval was granted in June of 2021. Although regulatory approval was obtained in Japan without specifying the primary organ or the history of treatment, there is limited evidence at this time, and guidelines recommend use after the second-line for midgut NETs and in the last phase for all other NETs. PRRT is expected to be utilized as upfront therapy, and the results of ongoing prospective clinical trials are awaited. The effect of PRRT is corelated with accumulation rate of somatostatin receptor scintigraphy(SRS). Sometime accumulation rate of SRS is not constant among multiple tumors in even one patient, then effective use of PRRT is depending on detailed exploration for result of SRS of each tumor. In order to perform this treatment in Japan, a special ward dedicated to radionuclide therapy or at least" a special measures patient room" prescribed by laws and regulations is necessary." A special measures patient room" is a general patient room with temporary isolation and taking radiation protection countermeasure, instead of the special exhaust and drainage systems of radionuclide therapy ward. On the other hand, in order to operate the rooms, it is necessary to set up and decontaminate the rooms for each treatment, which requires specialized knowledge and manpower. Since there is a growing demand for radionuclide therapies, it is important to promote the appropriate introduction of this therapy and to establish a collaborative network for this purpose.

The efficacy of multidisciplinary treatment, including neoadjuvant treatment, in borderline resectable pancreatic cancer (BRPC) remains unclear. We assessed the efficacy of neoadjuvant chemoradiotherapy with gemcitabine and tegafu/gimearcil/oteracil (S-1) for BRPC.In a single center, nonrandomized prospective study, neoadjuvant chemoradiotherapy (NACRT) with gemcitabine plus S-1 was administered for BRPC (no. B090312028) in 122 patients enrolled between 2009 and 2015. Gemcitabine plus S-1 comprised gemcitabine on days 8 and 15, and daily S-1 on days 1-14. After two courses of gemcitabine plus S-1, 30 Gy radiotherapy was administered in 10 fractions with S-1.Eighty-four and 38 patients had BR-PV and BR-A, respectively. No deaths occurred during NACRT. Ninety-four patients (77%) underwent resection with curative intent. R0 resection was performed in 91% of resected cases. Patients who underwent post-NACRT resection had better overall survival than did patients without resection (mean survival time [MST]: 24.7 vs 9.6 months, 5-year-survival rate (5 years): 30.3% vs 0%, P .001). Adjuvant chemotherapy was administered in 73% of patients. MST and 5-year survival rate of the patients treated with NACRT followed by resection and adjuvant chemotherapy were 29.6 months and 34.3%, respectively.Neoadjuvant chemoradiotherapy with gemcitabine and S-1 can be safely administered in BRPC and may require adjuvant chemotherapy.This study was registered with the University Hospital Medical Information Network-Clinical Trials Registry (UMIN-CTR) UMIN000006782.

Highlights • Proton beam therapy is likely to be safe for liver hemangiomas because, in our experience. • Proton beam therapy achieves good local control for liver hemangiomas without causing severe hepatic damage. • Proton beam therapy expected to minimize the risk of late adverse events., Background Hepatic hemangiomas are benign tumors with a favorable prognosis, but giant hepatic hemangiomas can cause abdominal symptoms and are indicated for treatment. Most cases are treated with surgery, but radiotherapy has also been used. However, to date, there have been no reports of proton beam therapy for a hepatic hemangioma. Case presentation A 46-year-old woman had a tumor of 80 × 80 mm in the left medial lobe of the liver, which was diagnosed as a giant hemangioma based on the contrast pattern. Therapy was required for a giant hepatic hemangioma with symptoms, but the patient refused blood transfusion due to religious reasons, which made surgical resection difficult. Therefore, she was referred to our hospital for proton beam therapy. At her first visit, liver function was Child-Pugh A (5 points) and there was no elevation of tumor markers. Proton beam therapy of 28.6 Gy (RBE) given in 13 fractions was performed without interruption. The only observed acute radiation toxicity was Grade 1 dermatitis. One year after proton beam therapy, the hemangioma had significantly decreased, and a complete response has been maintained for 15 years based on ultrasound and MRI. Conclusion This case is the first reported use of proton beam therapy for a hepatic hemangioma. The outcome suggests that this treatment may be effective for a giant liver hemangioma.

Background/Aim: We examined the difference between whole-brain radiation therapy (WBRT) for intracranial metastases (IM) from lung cancer as an initial and as a late treatment affecting overall survival (OS). Patients and Methods: Thirty-three patients who presented with IM at initial examination who received WBRT as the initial treatment (initial WBRT group) and 47 patients without IM or with asymptomatic IM at initial examination who received WBRT after systemic therapy, between January 2014 and December 2020, were retrospectively analyzed. Patients’ OS after WBRT were compared. Results: Median OS was significantly longer in patients treated with systemic anticancer therapy after WBRT than in patients who were not (176 vs. 47 days, respectively; p

Background Radiotherapy is often used for treating patients with gastric mucosa-associated lymphoid tissue (MALT) lymphomas who fail to respond to Helicobacter pylori eradication. However, non-gastric intestinal MALT lymphoma is rare, and no standard therapeutic strategies have been established. This study was designed to assess the long-term prognosis of non-gastric intestinal MALT lymphoma treated with radiotherapy and to compare the outcomes with that of post-radiotherapy gastric MALT lymphoma. Methods The study included 34 patients with stage I EA gastrointestinal MALT lymphoma according to the Ann Arbor classification who underwent definitive radiotherapy. The primary site was the rectum in 3, the duodenum in 1, and the stomach in 30 patients. The radiotherapy dose was 1.5?2.0 Gy (median, 1.5 Gy) and the total dose was 30?40 Gy (median, 30 Gy). The clinical target volume (CTV) was defined as the volume of the entire organ with the lymphoma. Adjacent lymph node areas were not routinely included in the CTV. Results Complete response (CR) was achieved in all patients. There were no local recurrences, and two cases of recurrence were observed at other sites. The 5-year overall survival rates for non-gastric and gastric MALT lymphomas were 100% and 94.7%, respectively, and the 5-year disease-free survival rates were 100% and 95.7%, respectively. None of the patients died of the current illness. Conclusion Radiotherapy for non-gastric intestinal MALT lymphoma is expected to result in good local control and long-term survival, similar to that for gastric MALT lymphoma.

Background/aim This study aimed to evaluate the effect of intensity-modulated radiation therapy (IMRT) on the clinical outcomes of patients with lymph node (LN) oligo-recurrence and a controlled primary tumor. Patients and methods We retrospectively reviewed the medical records of 21 patients diagnosed with LN oligo-recurrence who received IMRT with curative intent. Patients with tumor of various primary sites and histopathological types were included in this study. Results The 3-year overall survival (OS) and in-field progression-free survival (PFS) rates were 75% and 52%, respectively. Statistical analysis showed that lower dose to the gross tumor volume (GTV) and larger GTV were significantly associated with poorer OS; adenocarcinoma and lower dose to GTV were significantly associated with poorer in-field PFS. No patients experienced severe adverse events. Conclusion IMRT may provide a safe and effective treatment for patients with LN oligo-recurrence. Tumor dose-escalation sparing normal tissue using IMRT technology may improve the OS and in-field PFS.

Background/aim This study aimed to evaluate the clinical outcome of intensity-modulated radiation therapy (IMRT) and high-dose-rate intracavitary brachytherapy (HDR-ICBT) in uterine cervical cancer (UCC). IMRT consisted of whole-pelvic radiation therapy (WPRT) and sequential WPRT with central-shielding (WPRT-CS). Patients and methods Thirty UCC patients treated with IMRT using TomoTherapy, were retrospectively analyzed. Results The median dose of WPRT and WPRT-CS was 36 and 14.4 Gy and the median total dose of these was 50 Gy in 25 fractions (Fr). Median HDR-ICBT dose/Fr to Point A was 25 Gy/5 Fr. Median 2 Gy per fraction-equivalent dose (EQD2) of combined WPRT and HDR-ICBT to Point A (α/β=10) was 71.0 Gy. The 3-year local control, disease-free survival, and overall survival rates were 89.9%, 83.3%, and 86.3%. Conclusion IMRT of WPRT and WPRT-CS given in combination with HDR-ICBT was a feasible therapy resulting in good disease control and tolerance in patients with UCC.

The present prospective phase 1/2 study aimed to elucidate the efficacy and safety ofFrom April 2018 to October 2020, 15 patients with advanced NETs (five midgut, eight pancreatic, and two lung NETs) were enrolled. Objective response rate (ORR), progression-free survival (PFS), and adverse events (AEs) were evaluated. Pharmacokinetics and dosimetry were also evaluated in three midgut patients.The mean absorbed doses of

Preoperative whole pelvic radiation therapy (RT) is used commonly for rectal cancer and is the standard field postoperatively in gynecological cancer. However, the ideal field (local vs. whole pelvis) has not been determined for local recurrence of these cancers.We retrospectively reviewed the data for 52 patients who developed local tumor recurrence of rectal or gynecological cancer treated from 2013 to 2021. The initial treatment for all patients was total excision of the primary tumors without radiation therapy. Radiation therapy targets were surgical stumps, perianastomosis sites, and pelvic lymph nodes, classified according to the pelvic nodal volume atlas for radiation therapy. Patients were divided into the local recurrent tumor only radiation therapy group and the whole pelvis radiation therapy group. Whole pelvis radiation therapy included the common iliac lymph nodes or prophylactic lymph nodes below the L5/S1 junction. We recorded second recurrence after RT and the affected site(s) in each group. We also compared disease-specific survival using uni- and multivariate analyses.We found no significant differences between the groups regarding second recurrence or regarding the site(s) of recurrence. We also found no significant differences in disease-specific survival between the two RT groups. However, patients who did not receive chemotherapy after the initial surgery and before RT had significantly longer survival (P=0.015).In patients with locally recurrent rectal or gynecological cancer, we found no significant difference in second recurrence or survival between the local tumor only RT field and the whole pelvic RT field.

The most common secondary cancer is contralateral breast (CLB) cancer after whole breast irradiation (WBI). The aim of this study was to quantify the reduction of CLB dose in tangential intensity modulated radiotherapy (t-IMRT) for WBI using flattening-filter-free (FFF) beams.We generated automated planning of 20 young breast cancer patients with limited user interaction. Dose-volume histograms of the planning target volume (PTV), ipsilateral lung, heart, and CLB were calculated. The dose of PTV, the most medial CLB point, and the CLB point below the nipple was measured using an ionization chamber inserted in a slab phantom. We compared the two t-IMRT plans generated by FFF beams and flattening-filter (FF) beams.All plans were clinically acceptable. There was no difference in the conformal index, the homogeneity for FFF was significantly worse. For the ipsilateral lung, the maximum dose (DT-IMRT planning using FFF reduced the measured out-of-field dose of the most medial CLB point and the CLB point below the nipple.

Aim Whole‐breast radiation therapy after breast‐conserving surgery can control local recurrence with a long‐term survival rate equivalent to that of radical mastectomy for patients with early breast cancer. However, the significance of radiation therapy for patients with positive/close margins after mastectomy remains controversial. Following radical mastectomy, no residual breast parenchyma remains, and thus radiation therapy of the entire chest wall may represent overtreatment in the patients, especially those without lymph node metastasis (N0). We therefore implemented partial chest wall radiation therapy for patients with N0 breast cancer and positive and/or close margins after mastectomy. Methods A total of 22 patients with N0 status but positive/close margins underwent partial chest wall radiation therapy to irradiate the predetermined clinical target volume, which had margins of at least 2 cm medial, lateral, superior, and inferior to the primary tumor bed. With reference to chest wall thickness, 4‐10‐MV photons or 5‐8‐MeV electrons with/without a bolus were delivered. The total dose was 50‐66 Gy. We compared the results with those from 18 nonradiation therapy patients using Pearson's χ 2 test. Results All patients in the partial chest wall radiation therapy group achieved good local control despite having a significantly higher proportion of positive margins (77.3%) compared with the nonradiation therapy group (27.8%) (P = 0.002). Both groups showed 100% recurrence‐ and disease‐free survival. Conclusion Partial chest wall radiation therapy may offer recurrence‐ and disease‐free survival without local recurrence in N0 mastectomy patients with positive/close surgical margins.

BACKGROUND/AIM To evaluate whether factors related to the clinical staging of lymph node (LN) metastasis diagnosed by 18F-fluorodeoxyglucose positron-emission tomography/computed tomography (PET/CT) correspond to poor survival in esophageal squamous cell cancer (ESCC) patients treated with concurrent chemoradiotherapy (CCRT). PATIENTS AND METHODS A total of 69 patients with curative intent and no prior treatment for ESCC or simultaneous treatment for synchronous cancers were investigated. A maximum standardized uptake value (SUVmax) on the highest image pixel in the LN ≥2.5 was considered positive. Location of the involved LN and its impact on survival were analyzed. RESULTS In the univariate analysis of location, metastasis of the abdominal site, regional abdominal LN, and left gastric LN station negatively affected overall survival (OS) and disease-free survival (DFS). Other adverse clinical factors influencing OS included T4, clinical stage IVA and body mass index

Intensity-modulated radiation therapy (IMRT) delivers an excellent dose distribution compared with conventional three-dimensional conformal radiation therapy (3D-CRT) for postoperative radiation including the lymph nodes in breast cancer patients. The TomoTherapy system, developed exclusively for IMRT, has two treatment modes: TomoDirect (TD) with a fixed gantry angle for beam delivery, and TomoHelical (TH) with rotational beam delivery. We compared the characteristics of TD with TH and 3D-CRT plans in the breast cancer patients. Ten consecutive women with left breast cancer received postoperative radiation therapy using TD including the chest wall/residual breast tissue and level II–III axial and supraclavicular lymph node area. Fifty percent of the planning target volume (PTV) was covered with at least 50 Gy in 25 fractions. TD, TH and 3D-CRT plans were created for each patient, with the same dosimetric constraints. TD and TH showed better dose distribution to the PTV than 3D-CRT. TD and 3D-CRT markedly suppressed low-dose spread to the lung compared with TH. Total lung V5 and V10 were significantly lower, while V20 was significantly higher in the TD and 3D-CRT plans. The mean total lung, heart and contralateral breast doses were significantly lower using TD compared with the other plans. Compared with 3D-CRT and TH, TD can provide better target dose distribution with optimal normal-organ sparing for postoperative radiation therapy including the chest wall/residual breast tissue and lymph node area in breast cancer patients. TD is thus a useful treatment modality in these patients.

Background/Aim: To investigate the role and outcomes of radiation therapy (RT) for stage IVB uterine cervical cancer (UCC) patients with lung (oligo) metastases due to the lack of recent reports on the subject. Patients and Methods: The cohort for this retrospective study comprised 23 consecutive patients with UCC (squamous cell carcinoma, n=13) and lung metastases who had received pelvic RT. Ten had lung metastases only, including 7 with oligometastases (≤4 lung metastases); the remaining 13 also had other distant metastases. Results: Nine (39.1%) of the 22 patients (95.7%) completed RT without interruption. The 1-year primary progression-free rate was 95.2%. The 1-year overall survival rate was 47.2 % (estimated median survival: 9 months). Significant prognostic factors for survival included: i) ≤4 lung metastases (p=0.035), ii) unilateral lung metastases (p=0.039), iii) primary tumor diameter

Background/aim This study aimed to evaluate the outcome of radiation therapy for patients with distant lymph node (LN) metastases, without organ metastases from uterine cervical cancer (UCC). Patients and methods Twenty-six patients with UCC with distant LN metastases received radiotherapy and were retrospectively analyzed. The sites of distant LN metastasis were as follows; Supraclavicular in 19, inguinal in nine, axillary in four, and others in three. The mean dose prescribed for these was 50 (range=40-60) Gy. Results The 2-year overall, cause-specific, and progression-free survival, and local control of primary tumor rates were 51.3%, 51.3%, 46.9%, and 67.9%. In multivariate analysis, performance status ≥1 (p=0.007), para-aortic LN metastases (p=0.001), and lack of high-dose-rate intracavitary brachytherapy (p=0.033) were significantly associated with poor overall survival. Performance status ≥1 (p=0.004), and para-aortic LN metastases (p=0.014) were significantly associated with poor cause-specific survival. Conclusion This study demonstrated favorable local control in patients with UCC with distant LN metastases.

Background We compared outcomes and toxicities between concurrent retrograde super-selective intra-arterial chemoradiotherapy (IACRT) and concurrent systemic chemoradiotherapy (SCRT) for gingival carcinoma (GC). Methods We included 84 consecutive patients who were treated for non-metastatic GC ≥ stage III, from 2006 to 2018, in this retrospective analysis (IACRT group: n = 66; SCRT group: n = 18). Results The median follow-up time was 24 (range: 1–124) months. The median prescribed dose was 60 (6–70.2) Gy (IACRT: 60 Gy; SCRT: 69 Gy). There were significant differences between the two groups in terms of 3-year overall survival (OS; IACRT: 78.8, 95% confidence interval [CI]: 66.0–87.6; SCRT: 50.4, 95% CI: 27.6–73.0; P = 0.039), progression-free survival (PFS; IACRT: 75.6, 95% CI: 62.7–85.2; SCRT: 42.0, 95% CI: 17.7–70.9; P = 0.028) and local control rates (LC; IACRT: 77.2, 95% CI: 64.2–86.4; SCRT: 42.0, 95% CI: 17.7–70.9; P = 0.015). In univariate analysis, age ≥ 65 years, decreased performance status (PS) and SCRT were significantly associated with worse outcomes (P P Conclusions This is the first report to compare outcomes from IACRT and SCRT among patients with GC. ALL therapy related toxicities were manageable. IACRT is an effective and safe treatment for GC.

Background Concurrent chemoradiotherapy (CCRT) is the standard treatment for advanced esophageal cancer, but it may be more invasive in the elderly and definitive radiotherapy (RT) alone may be selected. This study assessed the significance of sequential chemoradiotherapy (SCRT) in elderly esophageal cancer patients. Methods We reviewed 87 patients aged 75 years and older, who were treated using definitive radiotherapy without concurrent chemotherapy for esophageal cancer. A total dose ranging from 50.4 to 63 Gy (median, 58.8) was delivered to the primary lesion and the involved lymph nodes. This study compared patients who received SCRT with those who received RT alone among 40 patients with stage III or IVA cancer. Descriptive statistics were calculated using Cox proportional hazards regression analysis and the generalized Wilcoxon test. Results The total progression-free survival (TPFS), progression-free survival outside the irradiation field, and overall survival were significantly longer after SCRT (n = 15) than after definitive RT alone (n = 25; P = 0.0041 and 0.0098), whereas the progression-free survival in the irradiation field was not significantly different between the two groups. The TPFS was significantly shorter in patients who received RT alone than in those who received SCRT (P = 0.0372). There were no grade 4 or higher adverse events in the patients who received SCRT. Conclusion SCRT was associated with a reduced relapse rate, suggesting that it should be considered for markedly elderly patients with advanced esophageal cancer.

Background The relationship between radiation dose to the ipsilateral lung and subsequent radiation-induced lung disease (RILD) in breast cancer patients with pectus excavatum (PE) undergoing radiation therapy (RT) to residual breast tissue after breast-conserving surgery has not yet been established. The incidence of RILD in such patients with PE, meaning that a large volume of the lung is within the radiation field, has not been determined. Therefore, the aim of this study was to determine the relationship between these factors. Methods The study cohort comprised 133 women who underwent three-dimensional conformal RT to residual breast tissue after breast-conserving surgery for breast cancer. Diagnoses of PE were based on Haller's, frontosagittal, and Monden's depression indices. Radiation doses to the ipsilateral lung were established from dose-volume histograms. Results Fifty of the 133 participants (37.6%) were diagnosed with RILD; all were asymptomatic. Multivariate analysis revealed a significant correlation between the incidence of RILD and the administration of > 30 Gy (V30). Surprisingly, although patients with PE received higher ipsilateral lung doses, they were less likely to develop RILD than those without PE. Conclusions Our data indicate that the incidence of RILD is correlated with the administration of > 30 Gy (V30) and that PE is not a risk factor for RILD after RT to residual breast tissue after breast-conserving surgery for breast cancer. Surprisingly, individuals with PE may have a lower incidence of RILD than those without this condition.

Background The relationship between radiation dose to the ipsilateral lung and subsequent radiation‐induced lung disease (RILD) in breast cancer patients with pectus excavatum (PE) undergoing radiation therapy (RT) to residual breast tissue after breast‐conserving surgery has not yet been established. The incidence of RILD in such patients with PE, meaning that a large volume of the lung is within the radiation field, has not been determined. Therefore, the aim of this study was to determine the relationship between these factors. Methods The study cohort comprised 133 women who underwent three‐dimensional conformal RT to residual breast tissue after breast‐conserving surgery for breast cancer. Diagnoses of PE were based on Haller's, frontosagittal, and Monden's depression indices. Radiation doses to the ipsilateral lung were established from dose‐volume histograms. Results Fifty of the 133 participants (37.6%) were diagnosed with RILD; all were asymptomatic. Multivariate analysis revealed a significant correlation between the incidence of RILD and the administration of > 30 Gy (V30). Surprisingly, although patients with PE received higher ipsilateral lung doses, they were less likely to develop RILD than those without PE. Conclusions Our data indicate that the incidence of RILD is correlated with the administration of > 30 Gy (V30) and that PE is not a risk factor for RILD after RT to residual breast tissue after breast‐conserving surgery for breast cancer. Surprisingly, individuals with PE may have a lower incidence of RILD than those without this condition.