Breast Conserving Surgery and Intraoperative Electron Radiotherapy (IOERT) Among Cases of Ductal Carcinoma In Situ

Background: Ductal Carcinoma In Situ (DCIS) which has recently beenrenamed into Ductal Intraepithelial Neoplasia (DIN), is a malignant cellproliferation without invasion to basement membrane of ducts or lobules of breast.DCIS consists ۲۰-۳۰% of newly diagnosed breast cancers in some Westerncountries due to higher diagnosis resulting from screening by mammography.Relative Risk (RR) of invasive ductal carcinoma is ۸-۱۰ times in DCIS, althoughhigh grading lesions and positive or close surgical margins are two importantpredictive factors in DCIS recurrences. The adjuvant radiotherapy has decreasedthe rate of ipsilateral local recurrence about ۶۰%. In this article, we evaluated therecurrence rate as DCIS as well as invasive breast cancer in patients with DCISundergoing breast conserving surgery (BCS) and intraoperative electronradiotherapy (IOERT). Methods: Data were derived from Cancer Research Center database from ۳۸pure DCIS cases who had received intraoperative radiation therapy between۲۰۱۲–۲۰۱۷. Intraoperative electron radiotherapy (IOERT) was performedaccording to Iran's intraoperative radiation therapy consensus. Results: The median age of the patients was ۵۵ years and median histologicallesion size was ۱.۸ centimeters. Number of extracted lymph nodes had a median of۱ and all extracted nodes were negative. Hormonal therapy was performed in۴۲.۱% of patients. IOERT was done as radical full exposure for ۸۶.۹% of cases andas boost dose for ۱۳.۱% of cases, who needed to complete radiotherapy by externalbeam. One case in the group received boost dose and ۴ cases in the group receivedfull dose had recurrence. The median follow-up of patients was ۳۱ months.Pathology of recurrence was reported as DCIS in ۳ cases and invasive breastcancer in ۲ of them. Conclusion: There is not a lot of data on the effectiveness of IOERT in DCISmanagement. Although there are not large number of cases in our study, the localrecurrence (۱۳.۱%) was only event in our study with ۳۱ months median follow upwith no contralateral metastasis, distant metastasis, or death.