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Breast Ductal Carcinoma in Situ, Intra-operative Radiotherapy, Partial Breast Radiation
Background: Ductal Carcinoma In Situ (DCIS) which has recently been renamed into Ductal Intraepithelial Neoplasia (DIN), is a malignant cell proliferation without invasion to basement membrane of ducts or lobules of breast. DCIS consists 20-30% of newly diagnosed breast cancers in some Western countries due to higher diagnosis resulting from screening by mammography. Relative Risk (RR) of invasive ductal carcinoma is 8-10 times in DCIS, although high grading lesions and positive or close surgical margins are two important predictive factors in DCIS recurrences. The adjuvant radiotherapy has decreased the rate of ipsilateral local recurrence about 60%. In this article, we evaluated the recurrence rate as DCIS as well as invasive breast cancer in patients with DCIS undergoing breast conserving surgery (BCS) and intraoperative electron radiotherapy (IOERT).
Methods: Data were derived from Cancer Research Center database from 38 pure DCIS cases who had received intraoperative radiation therapy between 2012–2017. Intraoperative electron radiotherapy (IOERT) was performed according to Iran's intraoperative radiation therapy consensus.
Results: The median age of the patients was 55 years and median histological lesion size was 1.8 centimeters. Number of extracted lymph nodes had a median of 1 and all extracted nodes were negative. Hormonal therapy was performed in 42.1% of patients. IOERT was done as radical full exposure for 86.9% of cases and as boost dose for 13.1% of cases, who needed to complete radiotherapy by external beam. One case in the group received boost dose and 4 cases in the group received full dose had recurrence. The median follow-up of patients was 31 months. Pathology of recurrence was reported as DCIS in 3 cases and invasive breast cancer in 2 of them.
Conclusion: There is not a lot of data on the effectiveness of IOERT in DCIS management. Although there are not large number of cases in our study, the local recurrence (13.1%) was only event in our study with 31 months median follow up with no contralateral metastasis, distant metastasis, or death.