Use of a recurrence score in second breast cancers

IntroductionSystemic treatment for second estrogen receptor positive (ER+) invasive breast cancer is controversial. The Recurrence Score (RS) from the 21-gene breast cancer assay (ODX) is used for adjuvant therapy recommendations in primary, early-stage ER+ disease, but has unknown utility in locally recurrent tumors.MethodsAn IRB-approved, single-institution retrospective chart review of a prospective ODX database of was performed. Most patients had ODX performed on an initial invasive breast cancer (1° Cancer); a minority had ODX performed on an ipsilateral local recurrence (2nd Cancer); none had clinical evidence of concurrent regional or distant metastasis at presentation. Eligibility for the ODX assay was based on NCCN guidelines (1° breast cancer) or physician discretion (2nd cancer). Data collected included demographics, clinical-pathologic variables, surgery type, RS, adjuvant treatment and outcomes. Comparisons between 1° breast cancer and 2nd were made by general linear regression model and the exact Wilcoxon Rank Sum Test.Results594 Patients with 1° breast cancer and 7 patients with 2nd breast cancer had ODX and RS. Median invasive tumor size of both 1° cancer and 2nd cancer was 1.5 (range 0.6-2.0 cm). All 1° and 2nd breast cancers were ER+. Median RS was higher in patients with 2nd cancer [25; range 15-40] compared to 1° cancer [16; range 0-63](p=0.0084). Categorically, more 2nd cancer patients had a high RS (37.5%) than those with 1° cancer (8.1%) (p=0.0136).ConclusionPerformance of ODX in ER+, locally recurrent breast cancer (2nd breast cancer) should be considered for prognostication and adjuvant systemic treatment recommendations