Abstract S2-05: 10-yr follow-up results of occult detected sentinel node disease: NSABP B-32, a randomized phase III clinical trial to compare sentinel node resection (SNR) to conventional axillary dissection (AD) in clinically node-negative breast cancer patients

Abstract

Abstract Background: NSABP B-32, the largest surgical prospective randomized phase III trial was designed to compare overall survival (OS), disease-free survival (DFS), and morbidity between SNR alone versus SNR + AD in SN negative (-) pts. This trial also had the opportunity to investigate the clinical significance of occult metastatic disease in sentinel nodes. We present the 10-yr data of the occult metastatic disease secondary endpoint outcomes analysis. Methods: 5,611 women with operable, clinically N0, invasive breast cancer were randomized to SNR + AD (G1) or to SNR alone with AD only if SNs were positive (G2). Pathologically negative sentinel nodes underwent a blinded detailed central pathology review using IHC stains for detection of occult metastatic disease. These findings were then analyzed for their effects on outcomes. Results: At 10 yrs, there continues to be no significant difference in OS (HR: 1.09, p = 0.35), DFS (HR: 1.02, p = 0.72), or local/regional recurrence (HR: 0.96, p = 0.77) between G1 and G2. Local-regional recurrences were 4.3% (G1) and 4.0% (G2) with axillary recurrences at 0.2% and 0.5% respectively. Median time on study was 131.1 months. Of the 5,611 pts., 3,989 were SN- and 3,986 (99.9%) of these SN- pts had follow-up information (G1: 1,975, G2: 2,011). 3,884 of these patients underwent blinded IHC analyses (1,924 [G1] and 1,960 [G2]). 616 patients were found to have sentinel node occult metastatic disease: 316 (16.4%) from G1 and 300 (15.3%) from G2. There was a nearly significant difference in OS between the occult and non-occult metastases groups (HR: 1.26, p = 0.06), and a significant difference in DFS between the two groups (HR: 1.24, p = 0.01) was found. Local-regional recurrence was not significantly different (HR: 0.8, p = 0.52). Occult local regional recurrences were 32 of the study total 165 (19.3%) with only 5 axillary recurrences in G2 related to SN occult detected disease. No statistical differences were found between the occult groups with and without axillary dissection for OS (HR: 0.98, p = 0.91) or DFS (HR: 0.82, p = 0.2). Conclusions: Although occult metastatic disease was detected in H&E negative sentinel nodes, its presence had no significant impact on OS, DFS, or local-regional recurrences in the large group of 5,611 patients. Specifically, in Group 2 with SN only, the 15.3% of pts with IHC positive nodes caused no significant impact on axillary failures. IHC use is not routinely recommended. Support: PHS grants: NSABP: U10CA-12027, U10CA-37377, U10CA-69651, U10CA-69974; VT Ca Cntr: P30 CA22435; DNK: 5RO1CA074137 NCI Dpt HHS. Citation Information: Cancer Res 2013;73(24 Suppl): Abstract nr S2-05.