Purpose: Published cross-sectional studies have revealed that chemotherapy for breast cancer is associated with significant cognitive impairments. However, because these studies included no baseline assessment, it is unknown whether the cognitive impairments were pre-existent to cancer treatment or truly secondary to chemotherapy. To resolve this issue, this prospective study aimed to compare the effects of chemotherapy to the effect of radiotherapy on cognitive functioning in women treated for non-metastatic breast cancer.

Patients and methods: A total of 81 breast cancer patients, 41 receiving chemotherapy as part of their breast cancer treatment regimen and 40 receiving radiotherapy without chemotherapy were evaluated using an extensive battery of neuropsychological tests at baseline (ie, pre-chemotherapy or pre-radiotherapy), post-treatment (ie, post-chemotherapy or post-radiotherapy) and at a 3-month follow-up assessment.

Results: A mixed model covariance analysis revealed that receiving any kind of breast cancer treatment, with chemotherapy or not, was associated with impaired capacities for recruiting information in verbal memory. Moreover, the results showed that verbal fluency was impaired after breast cancer treatment, but only in patients who received chemotherapy.

Conclusion: Overall, this study reveals subtle cognitive impairments associated with breast cancer treatment. Specifically, it suggests that chemotherapy has a specific negative effect on verbal fluency, that breast cancer treatment in general negatively affects verbal memory, but that other cognitive functions are well preserved. Future studies should, however, attempt to better control the practice effect that may have masked other subtle alterations and use more ecologically valid measures of cognitive functioning.