Catherine S. Hurt

Objectives Subjective reports of cognitive impairment following chemotherapy are frequent in cancer patients. Objective cognitive impairment has been observed in cancer patients regardless of treatment regimen suggesting the relationship between cognitive impairment and chemotherapy is not clear cut. Little research has explored the effects of chemotherapy on cognition following surgery in colorectal cancer (CRC). The present study explored the effects of chemotherapy on cognitive performance in a sample of CRC patients. Methods 136 participants were recruited into a prospective cohort study: 78 CRC patients undergoing surgery and adjuvant chemotherapy, 58 CRC patients undergoing surgery only. A battery of neuropsychological tests was administered to participants 4 weeks post‐surgery (T1), 12 weeks after first chemotherapy (T2) and 3 months after last chemotherapy (T3) or equivalent time‐points. Results Using the criterion of scoring at least two standard‐deviations below the group norm on at least one neuropsychological test, 45%–55% of all CRC patients showed cognitive deficits 10 months after surgery (T3) and 14% on at least 3 tests. However, cognition did not significantly differ between patients who had chemotherapy and those who did not. A time by group interaction effect was found on the composite cognition score using multi‐level modelling suggesting a greater improvement in cognition in the surgery only group over time ( p < 0.05). Conclusions CRC patients display cognitive impairment 10 months after surgery. Chemotherapy did not worsen cognitive impairment but did appear to slow cognitive recovery relative to those undergoing surgery only. The findings demonstrate a clear need for supportive cognitive interventions for all CRC patients following treatment.