Assessment of cognitive function after surgery for colorectal cancer—a scoping review

Objective Colorectal cancer is primarily treated with surgery. Major surgery and older age are risk factors associated with postoperative decline in cognitive function. In clinical research, a wide range of instruments have been used to assess cognitive function. There are no clear criteria for the measurement of postoperative cognitive dysfunction. This scoping review aimed to map how and when cognitive function has been assessed after surgery for colorectal cancer and the reported incidence of postoperative cognitive decline. Design Systematic scoping review following the JBI approach. Data sources Scopus and PubMed. Last search January 2023. Eligibility criteria Reports with outcomes of postoperatively assessed cognitive function in colorectal cancer patients with first assessment within 1 year of surgery were included. Data extraction and synthesis Data were extracted by one researcher and controlled for accuracy by a second researcher. Data were summarised in tables and charts. Results In total, 49 reports were included (16 clinical trials, 33 cohort studies). Cognitive function was assessed with patient-reported outcome measures, clinical screening tools, neurophysiological testing and complication classification. The definition was most often related to the specific instrument, as predefined cut-off or change from baseline. Assessments were performed between 1 hour and 36 months after surgery—few reports included follow-up both within and after 30 days postoperatively. Incidence of cognitive decline varied considerably (0%–64%), depending on the instrument, definition criteria and time of assessment. Most studies reported a decline in cognitive function after surgery with recovery during follow-up. Conclusions This study showed a heterogeneity in the choice of assessment method and measurement criteria for cognitive dysfunction after colorectal cancer surgery. A more unified measurement approach in further research would be beneficial to evaluate postoperative cognitive function and understand its impact on the daily lives of patients with colorectal cancer. Trial registration number 10.17605/OSF.IO/2M3DT.