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Background: Radiotherapy plays an essential role in breast cancer treatment following breast conserving surgery even in good-risk patients with ductal carcinoma in situ (DCIS) histology. It can be delivered by many techniques, among which is intraoperative radiotherapy (IORT). In recent years, intraoperative radiation therapy has had the same outcome compared with EBRT. Objectives: We studied whether whole breast radiotherapy (WBRT) could safely be replaced by IORT and its ability to control local recurrence like EBRT in pure DCIS. Methods: We assigned 138 patients into the external beam radiotherapy (EBRT), radical, and boost groups. The patients were treated during the last 6 years in the Cancer Research Center of Shahid Beheshti University of Medical Sciences. A total of 57 patients received EBRT, 45 patients received the radical dose of radiotherapy by IORT (36 patients received intraoperative electron radiotherapy [IOeRT] and 9 patients received intraoperative X-ray radiotherapy [IOxRT]) according to the IRIORT consensus protocol, and 36 patients received the boost dose of radiotherapy by IORT (15 patients received IOeRT and 21 patients received IOxRT). The IORT and EBRT groups were compared. The primary endpoint was local recurrence and death and the secondary endpoint was the role of variables in local recurrence. Results: With the mean follow-up of 37 months for the IORT group and 40.1 months for the EBRT group, local recurrence occurred in 8.8% (5 patients), 13.9% (5 patients), and 2.2% (1 patient) of the patients in the EBRT, boost, and radical groups, respectively. Concerning the local recurrence, no significant difference was observed between the radical and EBRT groups (P = 0.058) and between the boost and EBRT groups (P = 0.12). Hazard ratios (HRs) of grade, hormone receptor (HR), tumor size, and age in disease-free survival were evaluated and none of these variables had a significant role in local recurrence. Conclusions: IORT is a good alternative for WBRT in DCIS patients because of its non-inferiority results in comparison with EBRT. Being careful about age, tumor size, biological markers, and margin status is of high importance when using IORT for DCIS.

Background: Breast conserving surgery (BCS) and its following radiotherapy is an accepted therapeutic method for patients with invasive lobular carcinoma (ILC) and invasive ductal carcinoma (IDC). Objectives: The aim of this study was to investigate the effect of intraoperative electron radiotherapy on women with breast cancer (invasive lobular and ductal carcinoma). Methods: Between August 2013 and September 2017, 968 patients, who were referred to Cancer Research Center, Shahid Beheshti University of Medical Sciences with invasive breast cancer, were treated with breast-conserving surgery and radiotherapy. Of those, 426 patients received a tumor bed boost with intraoperative electron radiotherapy (IOERT) during lumpectomy (58 patients with pure invasive lobular carcinoma, 239 patients with pure invasive ductal carcinoma, and 129 patients with other diagnoses). 542 patients received a tumor bed boost with conventional external beam radiotherapy post lumpectomy (24 patients with pure invasive lobular carcinoma, 418 patients with pure invasive ductal carcinoma, and 100 patients with other diagnoses). The patients were followed up to 49 months. A comprehensive list of clinical and pathologic features was evaluated for all patients. We retrospectively analyzed outcomes of breast cancer treated with boost intraoperative electron radiotherapy (pure ILC and IDC groups) and in other group treated with boost conventional external beam radiotherapy (pure ILC group). Results: None of the ILC patients had recurrence in the two groups. The four-year survival rate for ILC patients was 100%, but in the IDC group the survival rate was 97%. Survival analyses showed patients with IDC had a higher risk of ipsilateral breast tumor recurrence (IBTR) and metastasis. Conclusions: Overall, the rates of IBTR and metastasis in the ILC boost IOERT group were significantly low. This finding suggests that IOERT technique deployment in ILC had no inferiority compared with the control group.