Subjective cognitive complaints one year after ceasing adjuvant endocrine therapy for early-stage breast cancer: Findings from the Breast International Group (BIG) 1-98 trial.

9022 Background: We have previously reported that, in the BIG 1-98 trial, objective cognitive function improved in postmenopausal women one year after cessation of adjuvant endocrine therapy for breast cancer. Here we evaluate changes in subjective cognitive function (SCF). Methods: One hundred postmenopausal women, randomized to receive five years of adjuvant tamoxifen, letrozole, or sequences of both, completed self-reported measures on SCF, psychological distress, fatigue and quality of life during the fifth year of trial treatment (year 5) and one year after treatment completion (year 6). Changes between years 5 and 6 were evaluated using the Wilcoxon signed-rank test. SCF and its correlates were explored. Results: Mean age of participants was 63.9 years [SD=7.1 years]. SCF and the other patient-reported outcomes did not change significantly after cessation of endocrine therapy with the exception of improvement in hot flushes (p=0.0005). No difference in changes was found between women who were taking tamoxifen or letrozole at year 5. SCF was the only psychosocial outcome with a substantial correlation between year 5 and 6 (Spearman’s R=0.80). Correlations between SCF and the other patient-reported outcomes were generally low. Conclusions: Although objective cognitive function improved after cessation of adjuvant endocrine therapy in the BIG 1-98 trial, improvement in SCF was not evident. The underlying reason for the clear disconnect between objective and subjective cognitive function seen in this and most other studies, is a crucial issue. It should be a research priority in order to effectively tackle the concerns of women about their cognition during and after breast cancer treatment.