Gene Assay Can Guide Chemo Strategies in Older Breast Cancer Population

The MammaPrint assay can help with treatment decision-making by identifying older patients who may benefit from chemotherapy for high-risk early-stage breast cancer, according to Reshma L. Mahtani, DO.

Mahtani, chief of breast medical oncology at Miami Cancer Institute of Baptist Health South Florida, spoke about the key findings of her presentation on real-world findings from the observational FLEX study (NCT03053193), which assessed the efficacy of the MammaPrint 70-gene assay in guiding treatment strategies for patients 70 years and older with early-stage breast cancer. She highlighted these findings in a poster session at the 2025 American Society of Clinical Oncology (ASCO) Annual Meeting.

Data showed that patients 70 years and older were less likely to receive chemotherapy than patients younger than 70 years if they had MammaPrint High 1 (H1) tumors (55.8% vs 73%; P <.001) or High 2 (H2) tumors (72.6% vs 82.2%; P = .07). Among older patients with high-risk tumors, chemotherapy conferred improved 3-year recurrence-free interval outcomes vs endocrine therapy alone for those with H1 (97% vs 94%; P = .137) and H2 (90% vs 79%; P = .078) tumors. These findings supported the conclusion that patient-centered discussions on performance status, comorbidities, potential chemotherapy benefit, and other factors should guide personalized treatment strategies.

Transcript:

Our study was based on the FLEX registry. By way of background, this is a large prospective, real-world observational study that collects clinical and genomic data from patients with early-stage breast cancer who undergo MammaPrint testing. The goal here is to evaluate how genomic test results influence treatment decisions and long-term outcomes across diverse patient populations and clinical settings.

In our study, we evaluated the relationship of age and treatment outcomes based on mammogram subtypes, and we looked at over 3000 patients who were younger than 70 years old, and a little over 1000 patients who were 70 years or older, from that FLEX registry. We provided some descriptive statistics in terms of the patient and tumor characteristics. Older patients were significantly less likely to present with high-grade tumors and lymph node involvement as compared with younger patients. Additionally, the MammaPrint risk distribution showed a significantly higher proportion of low genomic risk, either ultralow- or low-risk tumors in the older patients vs the younger patients. Older patients with MammaPrint high-risk tumors, either High 1 or High 2, were less likely to receive chemotherapy compared with those [who were] younger. Even with a high genomic risk, these patients who were older were less likely to receive chemotherapy. When evaluating 3-year relapse-free interval, the older patients with the MammaPrint high-risk tumors trended toward better outcomes with chemotherapy than those receiving endocrine therapy alone, especially in those with High 2 cancers.

Putting this together, these data suggest that the MammaPrint assay can help guide chemotherapy decisions in older women, potentially sparing low-risk patients from unnecessary treatment while identifying those who may benefit from chemotherapy despite their age, with the understanding that treatment decisions in this context are individualized, and comorbidities and other factors can also weigh in [the decision]. Some of these were not accounted for in our study.

Reference

Mahtani R, Sandoval-Leon A, Schreiber A, et al. Real-world evidence from FLEX: utility of MammaPrint in guiding treatment planning for patients aged 70 and older with early-stage breast cancer. Presented at the 2025 American Society of Clinical Oncology Annual Meeting; May 30-June 3, 2025; Chicago, IL. Abstract 11175.