Chemotherapy and gene expression profiling in older early luminal breast cancer patients: An International Society of Geriatric Oncology systematic review.

Background: The benefit of chemotherapy for older patients with hormone receptor (HR)-positive, human epidermal growth factor receptor 2 (HER2)-negative early breast cancer (EBC) is a key area of debate. Gene expression profiling (GEP) may identify patients deriving benefit, but their predictive role has not been established for older adults. We summarise evidence on efficacy, safety, and quality-of-life impacts of chemotherapy and on GEP use and impact in older HR-positive, HER2-negative EBC patients.

Methods: We conducted a literature search of PubMed and Embase on publications describing prospective studies evaluating chemotherapy in older adults with HR-positive, HER2-negative EBC and on publications describing retrospective and prospective studies evaluating GEP in older adults.

Results: Eight publications on chemotherapy use, including 2,035 older patients with EBC were selected. Only one trial evaluated chemotherapy survival benefits in older adults, showing no benefit. Of four studies comparing different regimens, only one showed the superiority of taxanes versus anthracyclines alone. Those investigating alternative regimens did not show improvements over standard regimens despite significant limitations. Five publications on GEP, including 445,323 older patients, were included and investigated Oncotype DX. Limited evidence shows that GEP aids treatment decisions in this population. GEP was offered less frequently to older versus younger patients. Higher Recurrence Score was prognostic for distant recurrence, but chemotherapy did not improve prognosis.

Conclusions: In older patients with HR-positive, HER2-negative, chemotherapy survival benefits EBC are unclear and GEP is less used. Although its prognostic role is well established, its predictive role remains unknown.