The MA.17R trial was performed to assess the benefit from extending aromatase inhibitor therapy with letrozole from 5 to 10 years in postmenopausal women with hormone receptor-positive early breast cancer. This trial is a North American Breast Cancer group trial that included participating cooperative groups from both USA & Canada and was led and coordinated by the National Cancer Institute of Canada Trials Group (NCIC CTG).
This was a randomized, double- blind, placebo- controlled phase III study of letrozole (2.5 mg/daily) compared to placebo in women who have previously received around 5 years (4.5-6 years) of any of the three currently used aromatase inhibitor therapies (letrozole, anastrozole or…show more content… Randomization with stratification was used to ensure that the treatment groups were well balanced at baseline. Patients were stratified by lymph node status at diagnosis, prior adjuvant chemotherapy, the interval between the last dose of aromatase inhibitor therapy and randomization, and duration of prior tamoxifen use.
As of April 2015, almost six years after the last woman was randomized to the study, only 171 events were observed and it was calculated that at least another 2 years of follow-up would be required to observe the required 196 events. Because of the continued decline in the event rate, and financial constraints associated with the extension of total duration of the trial, the protocol was amended with the primary analysis becoming time-based rather than event-based; eventually, final analysis was performed in Fall 2015 with 80% power to detect a hazard ratio of 0.65 for disease-free survival.
• The primary outcome measure was disease-free survival in both arms.
• The secondary outcome measures were: o the overall survival o Incidence of contralateral breast cancer o Long- term clinical and laboratory safety o Cardiovascular morbidity and mortality o Bone mineral density, the incidence of all bone fractures o Common toxicities o Quality of life between the two treatment arms.
Patients have been clinically evaluated annually with routine blood work, mammography,