Relevance of the review

Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer death, with an increasing incidence in low and middle-income countries. For stage I-III (T1-4 N0-2 M0) colorectal cancer, the treatment strategies provide surgical treatment alone or in association with systemic chemotherapy and/or radiotherapy. Among pharmacological therapies, anti-cancer drugs are associated with adverse physiological and psychological effects. Furthermore, up to 96% of people with colorectal cancer experience cancer-related fatigue, which can interfere with daily activities, mood, and quality of life (QoL). Moreover, of the 3.5 million colorectal cancer survivors worldwide, cancer-related fatigue has often been reported four years after diagnosis. Adverse effects associated with colorectal cancer and its treatments also include peripheral neuropathy, immune suppression, digestion issues, and bowel and bladder dysfunction (including faecal and urinary incontinence). Disease relapse and adverse effects can further impact physical activity, daily-living performance, mood, and QoL. A sedentary lifestyle has been identified as both a risk factor and a consequence of cancer-related fatigue. 

Physical activity programs have been proposed as non-pharmacologic interventions to reduce the negative cancer-related physiological and psychological effects. These programs include aerobic or strength exercises (including resistance, flexibility, and balance training) and may be either supervised or self-guided, in an individual or group setting. For example, early postoperative mobilisation is strongly recommended (encouraging postoperative patients to be out of bed for two hours on the day of surgery and six hours per day thereafter, until they are discharged from the hospital). Commonly, physical exercises are prescribed for 12 weeks, always taking into account the side effects (like chronic diarrhea) and comorbidities (cardiovascular, musculoskeletal, lung/breathing problems).

The positive impact of physical activity has been reported in cancer studies, both during and following treatment, where exercise training improves cardiorespiratory fitness, muscle strength, and overall health-related QoL. Evidence about the benefits of physical activity in colorectal cancer is unclear; thus, this review was done to evaluate the effectiveness and safety of these interventions on disease-related physical and mental health in this population.

This review is important for

Patients diagnosed with colorectal cancer, loved ones/caregivers, health professionals, general practitioners, researchers, and policymakers. 

Key outcomes of the review

The objective of this review was to assess the effectiveness and safety of physical activity interventions on the disease-related physical and mental health of individuals diagnosed with non-advanced colorectal cancer (staged as T1-4 N0-2 M0) treated surgically or with neoadjuvant or adjuvant therapy (i.e., chemotherapy, radiotherapy, or chemoradiotherapy). It included 16 studies (published up until June 2019), with 992 adults (age 51 to 69 years) randomly assigned to receive a physical activity intervention or usual care/no physical activity program. Physical activity consisted of supervised and/or self-directed walking, cycling, yoga, resistance exercises, and/or core stabilisation exercises for a minimum of four weeks.

Results suggest that physical activity interventions may increase aerobic fitness, may reduce fatigue (tiredness), and probably improve health-related QoL (general well-being). Moreover, physical activity interventions probably make little or no difference on disease-related mental health at short- and medium-term follow-up compared to usual care. The quality of evidence was low to moderate because of the low number of studies, small sample size, and study-design limitations. Moreover, it is uncertain if physical activity interventions improve physical function. Eight studies (out of 16) looked at adverse events and reported no serious events. None of the studies reported effects on the long-term follow-up or information about survival. 

Authors' conclusion

The findings of this review should be interpreted with caution due to the small number of studies and low quality of evidence. Physical activity interventions may be beneficial for aerobic fitness, cancer-related fatigue, and health-related QoL up to six months follow-up. This program may cause minor adverse events. 

Future recommendations

This review showed that there were inconsistencies in reporting outcomes of physical activity interventions and the measurement of adverse events. The authors suggest further randomized control trials with high-power, appropriate methodology and long-term follow-up; furthermore, adverse events should be adequately reported in order to establish the effectiveness of these programs on disease-related physical and mental health and survival of people with colorectal cancer.

Comment by Sunita Gudwani