A mechanistic cohort study evaluating cognitive impairment in women treated for breast cancer.

Some women report cognitive impairment after adjuvant chemotherapy (CTh) for breast cancer. Here we explore cognitive function, and underlying mechanisms with blood tests and functional magnetic resonance imaging (fMRI). Women treated for early breast cancer were recruited to three groups based on self-reported cognitive symptoms (CS) using FACT-Cog scores. CTh + CS+ (n = 44) had received chemotherapy and self-reported cognitive symptoms; CTh + CS- (n = 52) had chemotherapy but did not report cognitive problems; CTh- (n = 30) had not received chemotherapy. Clinical and computer-based neuropsychological tests were performed. Blood tests included 10 cytokines, sex hormones, coagulation factors, and apolipoprotein-E genotype. fMRI (n = 101) was performed while subjects performed an n-back memory task. Participants had median age 50 (range: 29-60) years and were a median of 17 months post-diagnosis. On clinical neuropsychological tests 19% had cognitive impairment using Global Deficit Score, and 36% using International Cancer and Cognition Task Force criteria with no significant differences in cognitive impairment rates between groups. CTh + CS+ had significantly more fatigue, anxiety/depression and poorer quality-of-life than other groups. There was no association between FACT-Cog and neuropsychological scores. There were significant differences in frontal and parietal regions on fMRI scans: CTh- showed hyperactivation compared to chemotherapy-treated groups, CTh + CS+ had more frontal activation than CTh + CS-. Elevated IL-1, IL-2 were associated weakly and IL-8 more strongly with neuropsychological impairment (rho > 0.20). There were no differences in global cognitive impairment between groups. Cognitive symptoms were associated with fatigue and anxiety/depression, but not with objective cognitive impairment. fMRI scans differed among the three groups.