Battling Cancer? Here’s How Exercise May Help.

A systematic review based on 65 meta-analyses showed that exercise improves cardiovascular fitness, muscle strength, cancer-related fatigue, depression and health-related quality of life (HR-QoL). The incidence of adverse events is also low, making exercise a valuable intervention for cancer patients.

Reference

Fuller, J., Hartland, M., Maloney, L., & Davison, K. (2018). Therapeutic effects of aerobic and resistance exercises for cancer survivors: a systematic review of meta-analyses of clinical trials. British Journal Of Sports Medicine, 52(20), 1311-1311. doi: 10.1136/bjsports-2017-098285

Background

Research on the effects of exercise on cancer outcomes has been growing rapidly. Numerous meta-analyses have been published on this topic, but no attempts have been made to summarise the collective findings in a way that informs health guidelines and policies. Hence, this systematic review aims to appraise meta-analyses that looked into the effects of exercise on health outcomes of cancer survivors, namely with regard to cardiovascular fitness, muscle strength, and Health-Related Quality of Life (HR-QoL), depression, and cancer-related fatigue.

What They Did

The researchers followed the PICOS system when designing the inclusion criteria. Studies have to meet the following conditions to be included for review:

P (participant): adults (aged ≥18 years) diagnosed with cancer

I (intervention): aerobic, resistance or combined aerobic and resistance exercises

C (comparison): standard care

O (outcomes): cardiovascular fitness, muscle strength, health-related quality of life, depression, and cancer-related fatigue

S (study design): peer-reviewed systematic reviews with meta-analysis of randomized controlled trials and quasi-experimental design studies

Sixty-five articles were included, and 57 of them have low risk of bias.

What They Found

Cardiovascular fitness:

  • 23 studies, 23/23 showed a beneficial effect, 20/23 of them were statistically significant.
  • Majority reported moderate or greater effect size.
  • The beneficial effect was lower in those who did resistance training only, and higher in those who did aerobic exercises only.
  • The beneficial effect was similar between those who exercised during or after completing cancer treatment.

Muscle strength:

  • 21 studies, 21/21 showed a beneficial effect, 20/21 of them were statistically significant.
  • Majority reported moderate or greater effect size.
  • The beneficial effect was similar between those who exercised during or after completing cancer treatment.

Cancer-related fatigue:

  • 42 studies, 42/42 showed a beneficial effect, 32/42 of them were statistically significant.
  • Majority reported small effect size.
  • The beneficial effect was higher in those who exercised after cancer treatment compared to those who exercised before cancer treatment.

HR-QoL

  • 34 studies, 34/34 showed a beneficial effect, 20/34 were statistically significant.
  • Majority reported small effect size.
  • The beneficial effect was higher in those who exercised during cancer treatment compared to those who exercised after cancer treatment.

Depression

  • 20 studies, 19/20 showed a beneficial effect, 12/19 were statistically significant.
  • Majority reported small effect size.
  • The beneficial effect was higher in those who exercised after cancer treatment compared to those who exercised during cancer treatment.

Adverse events

  • 21/65 reported incidence of exercise-related adverse events
  • 35 out of 1000 cancer survivors experience an adverse event related to exercise participation
  • Musculoskeletal pain or injury was the most common

Conclusion

Exercise has a positive effect on cardiovascular fitness, muscle strength, cancer-related fatigue, depression, and HR-QoL in cancer patients. The effect size is moderate for cardiovascular fitness and muscle strength but small for cancer-related fatigue, depression and HR-QoL. Precautions need to be taken to minimize risks of musculoskeletal-related pain or injury.

To maximise benefits on HR-QoL, include exercise DURING cancer treatment. To maximise benefits on cancer-related fatigue and depression, include exercise AFTER cancer treatment.

Practical Takeaways

Given that the incidence and survivorship of cancer are increasing, it becomes more likely for healthcare professionals and personal trainers to come across clients with cancer. It is not uncommon for cancer patients to feel that they are too frail or ill to be exercising. It is therefore important to educate them that exercise has minimal risks and numerous benefits for their physical and mental health.

Also, majority of the research on exercise oncology is based on patients with breast, ovarian, prostate or testicular cancer. Systematic reviews often do not have the scope to examine the efficacy of exercise on every type of cancer. Practitioners need to do their due diligence and find out if exercise is a suitable intervention to achieve their client’s goals.

Last but not least, cancer itself, together with its treatment, often produces complex symptoms and side effects. Medical clearance must be sought before starting any exercise regime, with advice from the primary care doctor on the unique contraindications and precautions that are specific to the client.