Clinical application of the 21-gene oncotype recurrence score in an older cohort: A single center experience

BACKGROUND: In early luminal breast cancer, the Oncotype DX® Recurrence Score (RS) prognostic and predictive value with regards to chemotherapy (CHT) application benefit has been broadly validated. In older patients its value has not been deeply addressed. This study aimed to evaluate the benefits of RS testing and to look at differences in treatment allocation for these patients when compared with younger ones. METHODS: We included data from consecutive patients with early luminal HER2-negative breast cancer, treated between 2010 and 2022 at the University Hospital Basel and Cantonal Hospital Baselland, Switzerland. The older cohort included 63 (19%) patients aged ≥70, and the younger cohort 263 (81%) patients aged <70. RESULTS: Older breast cancer patients had more co-morbidities (N = 36, 57% vs. N = 92, 35%, p = 0.002) and a higher clinical risk status (N = 49, 78% vs. N = 155, 59%; p = 0.01) when compared to younger patients. Histopathologic characteristics were significantly different between the two cohorts. Although older patients had a higher clinical risk status (78% vs. 59%) (p = 0.01), most of them (74%) received no CHT. Specifically, adjuvant CHT was administered less frequently in older than in younger patients (13% vs. 22%; p = 0.01). Moreover, older patients were less likely to complete CHT (>4 cycles: 78% vs. 97%). CONCLUSION: Breast cancer patients aged ≥70 have higher clinical risk status, more co-morbidities, higher clinical stage (driven by larger tumor size), and more often RS ≥26. However, they receive fewer adjuvant RT and CHT than those aged <70. RS maintains its independent prognostic value in older patients. However, assessing the predictive value of additional CHT benefit remains challenging due to significant differences in CHT administration. Although therapy decision-making in older patients with breast cancer still follows RS-based guidelines, clinical practice indicates an individualized treatment approach.