P3-13-02: The Impact of Lymph Node Status on Clinical Outcomes Following Accelerated Partial Breast Irradiation.
Authors: Shah C , Wilkinson JB , Wallace M , Vicini F 
Published: June 2012

Background: Limited data exists on outcomes following accelerated partial breast irradiation in node-positive breast cancer patients. The purpose of this analysis was to compare clinical outcomes following accelerated partial breast irradiation (APBI) between node-negative and node-positive early stage breast cancer patients and to identify if nodal positivity leads to increased rates of local or axillary failure. Materials and Methods: 510 patients with early stage breast cancer received accelerated partial breast irradiation (APBI) as part of their breast conservation therapy between April 1993 and November, 2010. Of these, 39 were lymph node positive with 10 patients having N1mi disease (median size of mets= 0.82 mm) and 29 patients having N1 disease (61.5% had one node positive [median size of mets= 2.5 mm], 30.8% had 2 nodes positive [median size of mets= 8.0 mm], and 7.7% had 3 nodes positive [median size of mets= 20 mm]). Patient, clinical, and pathologic factors were analyzed and compared for the node-negative and node-positive cohorts including age, tumor size, receptor status, margin status, adjuvant hormonal therapy, adjuvant chemotherapy, and length of follow-up. Clinical outcomes were analyzed including local recurrence (LR), regional recurrence (RR), axillary recurrence (AR), regional-nodal recurrence (RR), distant metastases (DM), disease-free survival (DFS), cause-specific survival (CSS), and overall survival (OS).

Results: Node-positive patients were younger (p=0.04), had larger tumors (p&lt;0.001), and were more likely to receive chemotherapy (p&lt;0.001). Median follow up was 5.3 years for node-negative patients and 5.9 years for node-positive patients (p=0.06). At 5 years, no differences were seen in the 5-year actuarial rates of LR (2.2% v. 2.6%, p=0.86), AR (0% v. 0%, p=0.69), DFS (90.0% v. 88.0%, p=0.79), CSS (98.0% v. 90.0%, p=0.06), or OS (91.0 v. 84.0%, p=0.65) while higher rates of RR (0% v. 6.1%, p&lt;0.001) and DM (2.2% v. 8.9%, p=0.005) were noted in node-positive patients. A total of 10 LRs occurred in the node-negative patients and 1 LR in the node-positive patients at a median of 2.6 and 1.5 years respectively. Both RR that developed in node-positive patients were within the supraclavicular fossa at a median of 2.8 years. Univariate analysis of LR was performed and age (p=0.31), tumor size (p=0.48), ER status (p=0.13), PR status (p=0.34), T-stage (p=0.48), chemotherapy (p=0.41), APBI technique (p=0.80), and nodal status (p=0.86) were not associated with LR while there was a trend for the association of LR with close/positive margins (p=0.07), and failure to receive adjuvant hormonal therapy (p=0.06). No variables were associated with any type of AR.

Discussion: No difference was seen in the rates of local recurrence or axillary failure between node-negative and node-positive following APBI with 5-years of follow-up. Increased rates of regional failure were noted with APBI in node-positive patients due to supraclavicular failures; however, traditional whole breast irradiation techniques would not have covered these failures.

Citation Information: Cancer Res 2011;71(24 Suppl):Abstract nr P3-13-02.