The impact of IMC nodal drainage on primary breast cancer outcome

Abstract

534 Background: Involvement of the internal mammary node chain (IMC) portends a poor prognosis in primary breast cancer. Theoretically, internal mammary node involvement cannot be present in the absence of primary tumor lymphatic drainage to these nodes. We examined whether the presence of IMC drainage negatively impacted regional and systemic recurrence and overall survival (OS). Methods: We performed a retrospective review of a prospective surgical database of patients with invasive breast cancer (Stage I-III) who underwent preoperative lymphoscintigraphy (LSG) with peritumoral injection and subsequent intraoperative lymphatic mapping from 1996-2002. The study was limited to 1,854 patients who demonstrated drainage on LSG and did not undergo IMC nodal biopsy. Medical records were reviewed for demographics, clinicopathologic data, and medical and surgical treatment data. Outcomes were evaluated including regional and systemic recurrence and overall survival (OS). Patients with any IMC drainage (IM+, alone or with axillary drainage) were compared to those without IMC drainage (IM-) as identified on LSG. Median follow-up was 57.9 months. Results: Three hundred forty-four (18.5%) patients showed IM drainage. Patients with IM drainage were younger and less likely to have upper outer quadrant tumors than those with non-IM drainage (p< 0.0001 for both). Tumor size and axillary sentinel node status were not significantly different between both groups (p=0.08 and p=0.39, respectively). There was no difference in IM irradiation rates of patients who were IM+ versus patients who were IM-. The 5-year systemic recurrence rate was 3.8% for IM+ patients and 2.1% for IM- patients (p=0.07). The 5-year regional recurrence rate was 0.9% for IM+ patients and 0.5% for IM- patients (p=0.46). Only one patient recurred in the IM nodal chain. There was no statistically significant difference in the 5-year OS rates of IM+ versus IM- patients in the entire study cohort as well as in the axillary node positive patients. Conclusions: A finding of IM drainage on LSG was not a significant predictor of OS during this study period. This finding needs to be confirmed at longer follow-up. Further studies are needed to determine the role of the IM sentinel node biopsy. No significant financial relationships to disclose.