Challenges With Patient Selection for Extended Adjuvant Endocrine Therapy in Breast Cancer

Cynthia X. Ma, MD, PhD, professor of medicine, Washington University in Saint Louis, Missouri, discusses the challenges with understanding treatment duration for adjuvant endocrine therapy in patients with breast cancer.

Multiple randomized studies have shown that extending the duration of endocrine therapy in the adjuvant setting does not significantly improve efficacy, said Ma. The real challenge is identifying patients who are at a higher risk for relapse and may, therefore, have a more significant benefit with prolonged endocrine therapy.

One prognostic tool that has been helping to overcome this challenge is the Clinical Treatment Score at 5 years (CTS5), a prognostic tool to aid treatment decision-making, for estimating distant recurrence risk in postmenopausal women. In the TransATAC study looking at breast cancer index and risk stratification in luminal subtypes, investigators found that initial tumor stage and tumor grade can affect late recurrence risk. Molecular gene signatures are another predictor of recurrence in these patients and can predict up to 10 years, explained Ma.

Other data hint that patients with HI-high ratio disease may benefit from longer treatment.

Even with this information, deciding which patients should receive extended endocrine therapy to prevent relapse continues to be a challenge for oncologists. Ma suggests additional research with prognostic testing before physicians can take these ideas into the community setting.