Patterns of relapse and risk for new malignancies following partial breast re-irradiation

Purpose Repeat irradiation of the breast is not commonly used. However, among patients with prior history of breast or mantle irradiation who refuse to undergo a mastectomy, treatment of localized breast cancer (BC) has included lumpectomy + re-irradiation. This paper is an update on our experience with lumpectomy and re-irradiation for localized BC with a focus on patterns of relapse. Methods The study includes 27 patients who had previously received radiation therapy (RT) to the involved breast. Nineteen patients had a prior history of BC treated with lumpectomy and whole breast RT via tangential fields. Eight patients with a prior history Hodgkin's disease (HD) were treated with mantle field irradiation and were subsequently diagnosed to have a second primary BC. The median time interval between diagnosis of the initial BC and recurrent/ new ipsilateral BC is 94 months (range 28-211 months), and between mantle RT and diagnosis of the second primary BC is 245 months (range 68-322 months). At the diagnosis of their new breast cancer, all patients underwent lumpectomy with negative margins and received partial breast irradiation (PBI) by using interstitial low-dose rate brachytherapy. A median dose of 45 Gy was delivered over 4-5 days. Results At a median follow up of 73 months following PBI, four (14.8 %) patients developed a local recurrence: three patients had prior history of BC and one had prior HD. All four local relapses were salvaged by mastectomy, and these patients remain with no evidence of local or regional failure. The 5-year Kaplan-Meier mastectomy-free survival is 81 %. Three patients developed distant relapse, and three patients developed a third new primary cancer. The 5-year actuarial risk for developing subsequent non-breast primary cancer was 30% among HD survivors and 0 % among patients with prior BC (p=0.004). Thus far, none of the patients with prior history of BC developed a second non-breast primary cancer. Conclusions Our observations suggest that patients with a history of prior irradiation who are motivated towards breast conservation have an alternative to mastectomy. Our observations suggest that lumpectomy with interstitial partial breast re-irradiation did not appear to have a detrimental effect on BC-specific outcomes. However, we did observe a high prevalence for third primary malignancy among patients initially diagnosed with HD, illustrating the importance of ongoing surveillance for subsequent cancer risk.