Postmastectomy Radiotherapy Can Decrease Locoregional Recurrence in Triple Negative T1-2N1 Breast Cancer Patients

Introduction: Postmastectomy RT (PMRT) is the subject of some debate in T1-T2 with one to three involved axillary lymph nodes (N1 disease).
Aim: Our study aims to compare between patients received PMRT and patients didn’t receive PMRT regarding locoregional recurrence (LRR) rate and also to define a subgroup of patients at high risk for locoregional recurrence (LRR) who might benefit from postmastectomy radiotherapy.
Patients and Methods: Retrospective study of patients with early stage breast cancer (T1-2) and positive 1- 3 axillary lymph nodes treated in clinical oncology department, Zagazig university during period between 2009 and 2014, we included 124 patients didn’t receive postmastectomy radiotherapy (No PMRT, group I) and 124 patients received postmastectomy radiotherapy (PMRT, group II).
Results: The median follow-up duration was 60 months (range; 11-72 months). Patients received PMRT had lower rate of LRR than patients didn’t receive PMRT (3.2% versus 35.5% respectively).Among patients didn’t receive radiotherapy, we found a significant high rate of locoregional recurrence (LRR) among triple negative patients than non-triple negative patients (61.5% vs 32.4%), also we found the relative risk reduction (RRR) in the LRR rate by PMRT was 81.9% and absolute risk reduction (ARR) was 50.4% (61.5% to 11.1%) among triple negative patients.
Conclusion: PMRT decreases locoregional recurrence rate (LRR) in early breast cancer with T1-2 and positive 1-3 axillary lymph nodes especially in patients had triple negative molecular subtype.