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Cancer substantially affects cognition: international research

3 November 2015

International research team finds even localised cancer is associated with sustained cognitive impairment.

Health professionals could help patients prepare for and cope with these changes by telling patients that memory loss may occur
Dr Haryana Dhillon

An international group of researchers has found cancer substantially affects memory, in the largest longitudinal cohort study assessing the impacts of the disease and its treatments on cognitive function.

Published in the Journal of Clinical Oncology in the United States, the study—which is also the first of its kind for colorectal cancer—found patients are up to three times more likely than non-cancer sufferers to suffer cognitive impairment.

The research, conducted by a team including experts from the University of Sydney, addresses the complaint many patients have that their memory and concentration is not as good after chemotherapy. 

It expands on previous studies into the effects of cancer on memory, concentration and multi-tasking, which have mostly been focused on younger women with breast cancer, and are often limited by small sample sizes and short-term follow-up.

The research found that the diagnosis of even localised cancer is associated with substantial rates of sustained cognitive impairment. 

Lead author Associate Professor Janette Vardy from the Sydney Medical School, said about 45 percent of people with colorectal cancer experienced changes in their memory and ability to process information, compared to about 15 percent of people without cancer.

“Future research needs to focus on the underlying mechanisms, and how to prevent and treat this cognitive impairment,” said Associate Professor Vardy.

Co-author Dr Haryana Dhillon, research fellow in the School of Psychology and a cancer survivorship expert at the University of Sydney, said the findings should help cancer sufferers everywhere.

“Health professionals could help patients prepare for and cope with these changes by telling patients that memory loss may occur, said Dr Dhillon, who is also a senior member of the University’s Centre for Medical Psychology and Evidence-based Decision-making.

“Medical practitioners can also assist by using techniques to help patients remember information discussed, and if problems persist referring them to a neuropsychologist for assessment.”

The main findings are: 

  • people diagnosed with colorectal cancer are three times more likely to have cognitive impairment when tested soon after their cancer diagnosis (but prior to any chemotherapy) than healthy controls, and this effect was sustained at 12 months post-diagnosis;  
  • there was no difference between rates of objective cognitive impairment at any time-point in colorectal patients who received chemotherapy and those who did not; 
  • women had more cognitive impairment than men at each assessment however men had more cognitive decline over time than women;
  • more participants who received chemotherapy had cognitive symptoms at six months (about the time chemotherapy ended) but by 12 months there was no difference in cognitive symptoms between the groups.

The study did not find any association between global objective cognitive function and fatigue, quality of life or symptoms of anxiety/depression.  

The study, the largest longitudinal cohort study assessing impacts of cancer and its treatment on cognitive function (memory, concentration, multi-tasking), included 289 people with localised colorectal cancer, 73 with limited metastatic/recurrent colorectal cancer and 72 non-cancer control participants.

An early release version of the paper can be viewed here.


Vivienne Reiner

PhD Candidate and Casual Academic
  • Integrated Sustainability Analysis,

Vivienne Reiner

Media and PR Adviser (Science, Veterinary Science, Agriculture)