Postmastectomy radiation for stage ll breast cancer patients with T1/T2 lesions.

175 Background: Post mastectomy radiation (PMR) is usually recommended for T3 or N2 breast cancer (BC). The role of PMR for stage ll BC with T1/T2 lesions remains controversial. The aim of this study was to assess the role of PMR in this subgroup of patients. Methods: A retrospective analysis of a prospectively collected database of all stage ll BC patients treated with mastectomy at our institution between 2005-2008 was performed. Demographics, tumor stage, histology, receptor status, adjuvant therapy, nodal status, failure patterns and disease free survival rates (DFS) were compared between the patients who received PMR vs.those who were not radiated. Results: Eighty-two patients underwent mastectomies for stage II disease with a T1/T2 lesion. Twenty two of those (27%) received PMR. The average follow up time was 47 months. The patients in the PMR group had significantly larger tumors (90% vs. 64%), more advanced stages (55% vs. 17%) and higher grade histology (59% vs. 32%). Menopausal status, nodal disease, histology, multifocality and receptors status did not differ significantly between the groups. Three patients in the non radiated (NR) group had a distant recurrence compared to 2 patients in the PMR group. There was one contra-lateral cancer in the NR group. The overall DFS was 86.6% in the NR group vs.91% in the PMR group, (p=0.72). Four patients had a chest wall recurrence (CWR) in the non-radiated (NR) group compared to none in the PMR group; however this was not statistically significant. In a sub-groups analysis comparing only T2, Stage IIB and high grade tumors respectively between the PMR and NR groups there was also no statistical difference in local or distant recurrence and in DFS. In the NR group, high grade tumors (p=0.0024) and estrogen receptors (ER) negativity (p=0.0168) were prognosticators of CWR. Conclusions: In our series PMR did not result in a statistically improved outcome for stage ll BC with T1/T2 lesions. A prospective trial randomizing patients with high grade or ER negative tumors only between PMR vs. NR could further clarify the role of PMR for stage II (T1/T2) lesions.