Cognitive Function Femara vs. Tamoxifen
The worry about diminished cognitive function is common and widespread among women who have been treated for breast cancer. There is much conversation about "chemobrain" which is still debated, but certainly seems very real to many people. The phrase is sometimes used more broadly to describe changes related not just to chemotherapy but other/all parts of the cancer experience. It is, of course, impossible to tease apart the many factors that may impact cognition. It has long been known that diminished estrogen (menopause) plays a role--as do worry, stress, less good sleep, feeling poorly, all the things that may accompany cancer treatment.
This is an abstract from a recent study, a very large multinational trial, that considered cognitive functioning of women who had been on letrozole (femara) or tamoxifen for five years. Like all single studies, it cannot be considered gospel, but it is one more piece of useful information.
Cognitive function in postmenopausal women receiving adjuvant letrozole or tamoxifen for breast cancer in the BIG 1-98 randomized trial Kelly-Anne Phillipsa , Karin Ribib , Zhuoxin Sunc , Alisa Stephensd , Alastair Thompsone , Vernon Harveyf , Beat Thürlimanng , Fatima Cardosoh , Olivia Paganii , Alan S. Coatesj , Aron Goldhirschk , Karen N. Pricel , Richard D. Gelberm , Jürg Bernhardn
Cognitive function in postmenopausal women receiving letrozole or tamoxifen as adjuvant endocrine treatment was compared during the fifth year of treatment in a substudy of the BIG 1-98 trial. In BIG 1-98 patients were randomized to receive adjuvant (A) 5-years tamoxifen, (B) 5-years letrozole, (C) 2-years tamoxifen followed by 3-years letrozole, or (D) 2-years letrozole followed by 3-years tamoxifen. The primary comparison was the difference in composite score for patients taking letrozole (B+C; N=65) vs. tamoxifen (A+D; N=55). The patients taking letrozole had better overall cognitive function than those taking tamoxifen (difference in mean composite z-scores=0.28, P= 0.04, 95% CI: 0.02, 0.54, Cohen's D=0.40 indicating small to moderate effect). In this substudy, breast cancer patients taking adjuvant letrozole during the fifth year of treatment had better cognitive function than those taking tamoxifen, suggesting aromatase inhibitors do not adversely impact cognition compared with tamoxifen.