Cognitive complaints during breast cancer endocrine therapy: aromatase inhibitors versus tamoxifen.

Objective: Previous data hypothesise that women receiving aromatase inhibitors (AIs) exhibit worse cognitive functioning than patients on tamoxifen (TAM) since their oestrogen levels are lower. We aimed to compare cognitive complaints in both groups.

Methods: From September 2020 to January 2021, we conducted a cross-sectional study on patients with stage I-III breast cancer undergoing adjuvant endocrine therapy for at least 6 months. Cognitive complaints were assessed using the Functional Assessment of Cancer Therapy-Cognitive V.3 questionnaire with higher scores indicating better outcomes.

Results: We included 108 female patients, 60 on AI and 48 on TAM. Mean age at diagnosis was 52 (44 in the TAM group vs 58 in the AI group, p<0.001). Assessment of 'perceived cognitive impairment-20 subscale' did not identify a significant difference between the two groups (mean score: patients on AI=63/80 vs patients on TAM=58/80, p=0.198). Patients on TAM scored significantly worse than patients on AI (p<0.001) on the concentration complaints, while for the verbal domain, memory, multitasking, speed and functional interference, no significant difference between the two groups was observed. The difference in concentration complaints was maintained after adjustment to age, educational level, physical activity, prior exposure to chemotherapy, and living alone or with others. Finally, a favourable impact of regular physical activity on concentration scores was observed in both groups (p<0.001).

Conclusion: Despite age difference, patients on AI did not demonstrate worse complaints than patients on TAM. Patients on TAM exhibited significantly increased concentration complaints. Oncologists should carefully screen their patients for mental fog and educate them on the importance of regular exercise.