Extended Letrozole Therapy in Postmenopausal Patients With Breast Cancer: How Long Is Long Enough?
Posted: Monday, November 1, 2021
Among postmenopausal patients with hormone receptor–positive breast cancer, prolonged treatment with 2 to 3 years of tamoxifen followed by 5 years of letrozole—for a total of up to 8 years of endocrine therapy—significantly improved invasive disease–free survival and overall survival. Lucia Del Mastro, MD, of the IRCCS Ospedale Policlinico San Martino, Genoa, Italy, presented these results from the Italian phase III GIM4 trial during the European Society for Medical Oncology (ESMO) Congress 2021 (Abstract 118O). The study was simultaneously published in The Lancet Oncology.
“Putting results in context with other trials…, we can consider a duration of 7 to 8 years total as the optimal duration of extended endocrine therapy. It’s a good compromise between efficacy and toxicity,” said Dr. Del Mastro in an article by Caroline Helwick in The ASCO Post.
This prospective trial enrolled 2,056 postmenopausal patients with stage I to III breast cancer who were free of recurrence after 2 to 3 years of tamoxifen therapy. Patients were randomly assigned 1:1 to receive 2 to 3 years (control group) or 5 years (extended group) of letrozole. Treatment was completed by 80% of patients in the control arm and 63% of patients in the experimental arm.
After a median follow-up of 11.7 years, 25% of those in the control group and 21% of those in the extended group experienced a disease-free survival event. The 12-year disease-free survival rate was 62% in the group receiving 2 to 3 years of letrozole and 67% in those receiving 5 years of letrozole (hazard ratio = 0.78, P = .006). According to the study investigators, this effect did not appear to be influenced by nodal status, tumor size, grading, patient age, hormone receptor status, HER2 status, previous chemotherapy, or body mass index. The 12-year overall survival rates were 84% and 88% in the control and extended arms, respectively (hazard ratio = 0.77, P = .036).
There were 263 total deaths reported among study participants: 147 in the control arm and 116 in the extended arm. The most common adverse events seen in both groups were arthralgia (31% control vs. 38% experimental), myalgia (8% vs. 12%), hypertension (1% vs. 2%), and osteoporosis (5% vs. 8%).
Disclosure: For a full list of authors’ disclosures, visit oncologypro.esmo.org.
