Oncotype DX recurrence score in node-positive patients in the post-RxPONDER era: a single-institution experience.

Purpose: RxPONDER showed that in postmenopausal women with early-stage hormone receptor + /HER2- breast cancer (BC) with 1-3 positive axillary lymph nodes (LN) and a recurrence score ≤ 25, the addition of chemotherapy to endocrine therapy did not improve distant recurrence-free survival. We sought to evaluate Oncotype DX recurrence score (ODX RS) distribution in LN negative and LN positive patients aged ≥ 50 years (y) and to determine clinicopathologic factors associated with RS.

Methods: ODX RS, demographic, and pathologic information was collected for patients with ER + /HER2- BC with 0 (patients < 50y) or 0-3 positive (patients ≥ 50y) LN treated at our institution between January 2021 and December 2022. Statistical analyses were conducted using Pearson chi-square and two-tailed t tests.

Results: The study cohort included 2378 BC from 2285 women. Among women ≥ 50y, there was no significant difference in RS distribution between pN0, pN1mi, and pN1a patients; with 85.4%, 86.5%, and 81% having a RS ≤ 25, respectively. Among LN + women ≥ 50y, RS > 25 was significantly associated with higher grade (P = .001), lower ER (P = .007), and lower PR (P < .001). Among LN- women ≥ 50y, RS > 25 was significantly associated with higher grade (P < .001), lower ER (P < .001), and lower PR (P < .001).

Conclusion: ODX RS distribution among LN + and LN- women aged ≥ 50y was similar. In this population, RS is significantly associated with tumor grade, ER, and PR, regardless of LN status. In our post-RxPONDER era cohort, over 80% of women aged ≥ 50y with early-stage ER + /HER2- BC with ≤ 3 positive axillary LN would be spared chemotherapy based on RS, regardless of nodal status.