The clinical impact and outcomes of immunohistochemistry-only metastases in breast cancer

Abstract

613 Background: Modern surgical and pathologic techniques can detect small volume axillary metastases in breast cancer. The clinical significance of these metastases was evaluated in comparison to patients with negative sentinel lymph nodes (Neg-SN). Methods: Retrospective database review from 1997 through 2003 for eligible patients with unilateral breast cancer and no history of significant non-breast malignancy identified 232 patients with sentinel lymph node (SLN) metastases identified only by immunohistochemical stains (IHC-SN). They were compared to 252 Neg-SN controls selected at random from the same database population. Statistical analysis was performed with 2-sample tests, Kaplan-Meier, and Cox regression methods. Results: IHC-SN patients had worse prognostic features and received more systemic therapy than controls (Table). Age and ER status were similar. In 123 IHC-SN patients treated with axillary dissection (ALND), 16% had macrometastases in the non-SLNs. Only one axillary recurrence occurred in the group of IHC-SN patients without ANLD (n=109). With median follow up of 5 years (range 0.01–12.0), 28 recurrences and 25 deaths occurred. There were no differences between cases and controls for recurrence-free survival (RFS) or overall survival (OS) both by univariate and multivariate models that included variables such as age, tumor size, chemotherapy and hormone therapy [HR 0.99 (95%CI 0.43–2.28, p=0.99) for RFS, HR 2.06 (95%CI 0.79–5.35) p=0.14 for OS]. In IHC-SN patients treated with ALND, patients with positive non-SLNs (n=20) tended to have worse RFS than those with negative non-SLNs (n=103) [RFS 89% vs. 97% at 5 yrs (p=0.06)]. Conclusions: A significant number of IHC-SN patients had a macrometastasis identified at ALND. In patients not undergoing dissection, axillary recurrence was a rare event. However, failure to identify additional metastases by omitting ALND may result in understaging and inadequate systemic treatment in some patients. [Table: see text] No significant financial relationships to disclose.