Metastatic colorectal cancer patients who engage in moderate exercise while having chemotherapy tend to have delayed disease progression and fewer severe side effects, according to a US study.

Even low-intensity exercise, such as walking four or more hours a week, was associated with a nearly 20% reduction in cancer progression or death over the course of the six-year study, said researchers.

“Physically active patients in our study also appeared to tolerate chemotherapy better” Brendan Guercio

The data also hinted at a possible lengthening of survival in patients who reported greater physical activity, but the data were not statistically significant, said the US researchers.

They noted that previous studies had found that regular exercise could reduce the risk of disease recurrence and death from colon cancer that has not metastasized to other parts of the body.

However, they said theirs was the first study to examine associations of physical activity with survival in advanced, metastatic colorectal cancer.

The data used in the new research on exercise, which involved a total of 1,218 people, came from patients who had participated in a phase 3 study of chemotherapy for advanced colorectal cancer.

Within a month after beginning treatment, the patients in the trial were invited to complete a questionnaire about their average physical activity over the previous two months.

“People who engaged in some type of physical activity had a statistically significant improvement in progression-free survival” Jeffrey Meyerhardt

Based on the patients’ descriptions, researchers quantified physical activity in terms of metabolic equivalent task (MET)-hours per week – a standard measure used in research studies of exercise.

Vigorous activity was defined as any activity requiring six or more METs, such as running, biking, tennis, skiing, or lap swimming. Non-vigorous activities included walking, climbing stairs, or yoga.

Analysis of the data revealed a statistically significant difference in progression-free survival (PFS) – the time after a patient completed the questionnaire before the cancer progressed or they died.

The difference in PFS was almost 20% in favour of those who exercised more, said the researchers from the Dana-Farber Cancer Institute and Brigham and Women’s Hospital in Boston.

Meanwhile, patients who engaged in 18 or more MET-hours per week of activity had a 15% improvement in overall survival than those who engaged in less than three MET-hours a week.

However, that difference was not statistically significant, meaning it could have resulted from chance, noted the study authors in the Journal of Clinical Oncology.

Jeffrey Meyerardt Source: Dana-Farber Cancer Institute Jeffrey Meyerhardt

Senior study author Dr Jeffrey Meyerhardt said: “What we found was that people who engaged in some type of physical activity had a statistically significant improvement in progression-free survival.

“While there may also be an impact on overall survival, it was not statistically significant – and should be studied further.”

Dr Meyerhardt said the findings also helped “justify” encouraging patients to exercise and referring patients to physical therapists or programmes that do small group training for those with cancer.

Dr Brendan Guercio, first author of the study, added: “Physically active patients in our study also appeared to tolerate chemotherapy better.

“Total physical activity equivalent to 30 or more minutes of moderate daily activity was associated with a 27% reduction in severe treatment-related toxicities.”