Post-mastectomy radiation beyond chest wall in patients with N1 breast cancer: is there a benefit?

Nodal stage is the most important prognostic factor and one of the indicators for loco-regional radiation in patients with breast cancer. N1 (patients with 1-3 lymph node metastases in axilla) nodal stage is a controversial area as far as axillary and supraclavicular fossa (SCF) irradiation is concerned. We conducted a retrospective analysis at our institute to assess the impact of post-mastectomy radiotherapy (PMRT) beyond chest wall (CW) in N1- nodal stage breast cancer patients.

Since January 2004 to December 2007, 293 post-mastectomy patients with N1 nodal stage breast cancer were analyzed for patient-related characteristics such as age, menopausal status, pathological stage/tumour size, tumour location, histology, oestrogen/progesterone receptor status, histological grade, extra capsular extension, lymph vascular invasion and treatment-related factors, PMRT and systemic therapy. Outcome studied were locoregional recurrence rate (LRR), disease free survival (DFS) and overall survival (OS).

At a median follow up of 55m, 260 patients received radiotherapy; 212 to CW+SCF, 48 to the CW only; and 33 patients did not receive radiotherapy. LRR was 5% in patients who received radiotherapy to CW+SCF and 8% in CW only (P = 0.34). There was no difference in the DFS between the two groups. OS at 5 year was 88% in CW+SCF group and 76% in CW only group respectively (P < 0.001).

In N1 nodal stage patients with breast cancer LRR was not significantly different after radiation to CW+SCF or to the CW only but OS was significantly better.