Cognitive impairment is substantially greater in patients with colorectal cancer (CRC) than in healthy persons. Treatment with chemotherapy does not significantly add to this effect. These findings are reported in a study published online ahead of print in the Journal of Clinical Oncology.1

The researchers sought to identify changes in cognitive function and underlying mechanisms of actions in patients with CRC.

They recruited 289 patients with localized CRC, 173 of whom received chemotherapy; 73 patients with limited metastatic/recurrent CRC; and 72 HCs. Primary end point for the study was overall cognitive function measured by the Global Deficit Score at 12 months.

Continue Reading

To conduct the study, researchers had participants complete assessments and questionnaires focusing on cognitive symptoms, fatigue, quality of life, and anxiety/depression at baseline (before chemotherapy in those who received it) and at 6, 12, and 24 months. Blood tests measured cytokines, clotting factors, apolipoprotein E genotype, and sex hormones.

At baseline and at 12 months, more patients with localized CRC had cognitive impairments than did HCs, with symptoms reported in 25% of patients with localized CRC vs. 17% of HCs. Cognitive impairment was similar in both CRC groups.

More patients who received chemotherapy had cognitive symptoms at 6 months compared with those who did not; however, no significant difference was seen at 12 months.

Skills most affected were attention/working memory, verbal learning/memory, and complex processing speed. Other results included higher cytokine levels in patients with CRC compared with HCs, but no association was seen between overall cognitive function and fatigue, quality of life, anxiety/depression, or any blood test.

The results demonstrated substantially greater impairment in patients with CRC compared with HCs with every assessment method. Mechanisms of cognitive impairment, however, remain unknown.


1. Vardy JL, Dhillon HM, Pond GR, et al. Cognitive function in patients with colorectal cancer who do and do not receive chemotherapy: a prospective, longitudinal, controlled study [published online ahead of print November 2, 2015]. J Clin Oncol. doi:10.1200/JCO.2015.63.0905.