Exercise recently has been dubbed a polypill, and the effects of physical activity have proved to have a role in preventing many diseases including certain cancers. But is exercise also beneficial once a disease of the magnitude of cancer has appeared? Cancer is a broad term that includes many different types of locations, systems and treatment plans, but patients who suffer from cancer are known to become weak and experience decreased fitness. This is due both to the cancer itself and to the different treatments, such as surgery, chemotherapy, radiotherapy or a combination of treatments. These treatments can leave cancer patients feeling fatigued and lacking stamina, with muscle atrophy. This might lead to a decrease in activities and participation in their normal lifestyle and therefore can contribute to a decrease in quality of life. This decline in fitness can persist over time and is known adversely affect outcomes of cancer treatment.
In order to identify whether exercise has a significant impact on cancer treatment outcomes, this Cochrane Systematic Review analysed publications that studied the impact of exercise interventions in cancer patients.
A total of 11 studies involving 1.067 patients were included in the analysis. Exercise interventions were used with different cancers, breast cancer being the most common type for which exercise complementary treatment was used. Patients with cancer were randomly assigned to receive an exercise programme compared to the usual care in order to investigate if there was an additional effect of the programme. Studies employed a variety of intensity, type and duration of exercise interventions. Duration ranged from 5 to 18 weeks. The programme included a combination of aerobic, strength, balance, coordination, yoga and stretching techniques and was prescribed for 2 or 3 sessions per week.
The effect of the physical exercise intervention was measured with physical fitness parameters such as the volume of consumed O2, the 6-minute walking distance test or the grip-strength test. Safety and Health Related Quality of Life (HRQoL) scales, and fatigue scales also were administered for secondary outcomes.
The revision concludes there is low-certainty evidence of exercise training's effect on physical fitness after cancer although it is safe. Moderate-certainty evidence suggests an impact on HRQoL.
However, this review is based on a small sample of studies with different types of cancer, with individuals undergoing treatments and exercise interventions varying in type, duration and outcome measurements; therefore, further research should be conducted.
Nevertheless, due to the positive effects and the safety of physical activity, exercise should be promoted as a coadjuvant intervention.
Comment by Sara Laxe