Chapter 01 - Safeguarding Exercise Capacity Throughout and After Cancer Treatment
Several reviews and meta-analyses demonstrate beneficial effects of physical activity and exerciseb in cancer survivors during and after treatment on physical and psychosocial outcomes. These include increased cardiorespiratory fitness, muscle mass and strength, reduced fatigue and depression, and improved QoL. The Physical Activity across the Cancer Continuum (PACC) framework proposes four time periods following diagnosis during which physical activity can have an important role: pre-treatment, during treatment, survivorship, and end-of-life care.
The aim of exercise pre-treatment is to improve physical fitness (including cardiorespiratory fitness and muscle strength) prior to surgery or systemic therapy to enable patients to undergo treatment with fewer side effects or to enhance post-treatment recovery. In a systematic review of randomised controlled trials (RCTs) and non-RCTs, Singh and colleagues reported that the data available from patients with lung cancer, prostate cancer, and cancer of the abdominal area (e.g. colon, colorectal, liver) suggest that exercise – aerobic, resistance, or pelvic floor training alone or in combination – may have a positive effect on rate and duration of continence, functional walking capacity, and cardiorespiratory fitness. Some studies reported improved QoL and reduced length of hospital stay (which is an important prognostic variable for a positive surgical outcome), but findings were inconsistent, likely due to lack of power and differences in training duration prior to surgery.
In a meta-analysis by Speck and colleagues, results of exercise during and after cancer treatment were presented separately. During treatment, small to moderate significant effects of exercise were reported for cardiorespiratory fitness, upper and lower body muscle strength, body weight, functional QoL, anxiety, and self-esteem. After treatment, large significant effects were found for upper and lower body muscle strength and breast cancer-specific concerns, and small to moderate significant effects for physical activity level, cardiorespiratory fitness, overall QoL, fatigue, insulin-like growth factor-1 (IGF-1), and symptoms and side effects. Similar effects were reported in other meta-analyses on this topic.
Resistance exercise is a potent stimulus of muscle synthesis, and consequently increasing muscle mass, endurance, and strength, thereby improving physical function and QoL. Exercise (aerobic, resistance, or a combination of both) during cancer treatment can improve upper and lower body muscle strength more than usual care. In a recent meta-analysis of RCTs evaluating the effects of resistance exercise during and after cancer treatment, Strasser and colleagues reported a significant increase in lower and upper body muscle strength and lean body mass.
Improvements in lower body muscle strength were greater in cancer survivors who completed an exercise intervention after cancer treatment, compared to those who exercised during cancer treatment. Whether there is a dose–response relationship remains unclear; however, the results suggest that exercise volume may be more important than exercise intensity in order to induce muscle protein synthesis.
Exercise and, in particular, resistance training and high-impact loading exercise can positively influence bone health by its osteogenic effects. Resistance exercises should be performed at sufficient intensity and should specifically load a target bone, thus both the hips and the spine. Weight-bearing activities such as jumping and skipping are more osteogenic than activities with lower impact forces; however, aerobic exercises using upper and lower body muscles and/or trunk rotation at sufficient intensity, such as aerobic dance, may also benefit patients with osteogenesis. Walking interventions generally have limited effect on bone health because the relatively low ground reaction force does not reach sufficient intensity to augment bone density.
The relative benefit of exercise versus pharmacological treatment is yet to be determined. Although exercise can be an effective non-pharmacological strategy for preserving bone health during and after cancer treatment, adequate calcium and vitamin D supplementation and treatment with pharmacological agents such as bisphosphonate and RANK-ligand monoclonal antibody may also be important. These agents are, however, associated with considerable side effects.
Few studies have examined the effects of physical activity in palliative cancer patients. The few case reports and uncontrolled trials available suggest that the role for physical activity is promising, as it may maintain physical function, independence in activities of daily living, and overall QoL. It is therefore recommended to encourage palliative cancer patients to consider a physical activity intervention under the specific direction and guidance of their attending medical team.
bExercise is a specific type of physical activity that is planned, structured, and repetitive and aims to improve or maintain physical fitness, performance, or health.