Frequency of Breast Conserving Therapy Following an Ipsilateral Local Relapse in Patients With Ductal Carcinoma In Situ (DCIS) Treated With Lumpectomy (L) ± Radiation Therapy (RT)

Purpose/Objective(s): Breast conserving therapy (BCT) is a well accepted alternative to mastectomy in patients diagnosed with DCIS. In the event of a local relapse following BCT a second L RT is considered a more viable option for patients initially treated with L alone compared to those treated with L + RT. In the literature, however the rate of BCT after local relapse in these patients is not well described. The objectives of this study were to review our outcomes for DCIS treated with L RT, and further to evaluate the rates of BCT following an ipsilateral breast relapse. Materials/Methods: This is an IRB approved study on a prospectively maintained breast cancer database. From 2000-2012, 692 patients with pure DCIS, excluding all patients with a prior or synchronous diagnosis of invasive cancer, were treated with BCT. Among them, 297 patients underwent L alone hormones, and 392 had L + RT hormones. On review of patient characteristics by type of treatment received, we noted that patients in the L + RT group had higher risk features as compared with the patients treated with L alone. They were more likely to be younger (p Z 0.0007), having a higher frequency of PR negative status (p < 0.03), larger size DCIS (p < 0.0001), and requiring more than one re-excision to achieve clear margins of resection (p < 0.0001). Patients receiving RT were treated to the whole breast and boost. Results: The median follow-up is 5.04 years, and the overall actuarial 5year local relapse-free survival (LRFS) is 93%. By the type of treatment received, the 5-year LRFS for L alone and L + RT was 91% and 94%, respectively. Among the 50 local failures observed, 28 were noted in the L alone group and 22 in the L + RT group. At relapse, 35% were diagnosed with invasive cancer and 65% had DCIS. Despite the available option of second L RT for relapses after initial treatment with L alone, we noted that 40% (n Z 11) patients ultimately underwent mastectomy. Among the relapses in the L+RT group, 75% of patients underwent mastectomy. The remainder either refused mastectomy or were treated on the RT re-treatment protocol. Conclusions: We observed a trend towards better local control among the L + RT patients. Further, despite the relatively lower risk patients treated with L alone the rates of local relapse are not insignificant, and are quite comparable to the high risk patient treated with RT. Further, we noted that the option BCT at relapse was realized only 60% of the time in patients who were treated with L and did not receive RT initially. This outcome data may be useful in providing DCIS patients an informed consultation on their treatment options. Author Disclosure: M. Chadha: None. D. Miller: None. C. Shan-Chin: None. S.K. Boolbol: G. Consultant; Genomic Health. A. Gillego: None. K. Boachie-Adjei: None. L.B. Harrison: None.