Schmitz, K. H., Holtzman, J., Courneya, K. S., Masse, L. C., Duval, S., & Kane, R. (2005). Controlled physical activity trials in cancer survivors: a systematic review and meta-analysis. Cancer Epidemiology, Biomarkers and Prevention, 14, 1588–1595.

The database searched was MEDLINE through February 2005 to identify intervention studies designed to increase physical activity in adults. Only those studies with a concurrent comparison group with results presented separately for treatment and comparison groups were included.

The quality of 32 studies was assessed using prespecified criteria for internal validity. Twenty-two of 32 studies were rated as being of high methodologic quality and were retained for qualitative and quantitative analysis. The outcomes of physical activity interventions in patients receiving active treatment were analyzed separately from the studies of physical activity after treatment was concluded.

Outcomes were fatigue, health-related quality of life, symptom distress, immune function, hematocrit, body composition, physical exercise capacity (maximal oxygen consumption), and other physical performance measures.

Treatment evaluated aerobic physical activity of moderate to vigorous intensity three to five times per week for 20 to 30 minutes per session. The majority of the interventions lasted between five weeks and three months, with no follow-up at the end of the intervention. The majority of the studies used a control group in which no physical activity or other treatment was prescribed, although a few studies provided an intervention for the comparison group.

• Average sample size for the intervention group was 28 participants.
• The most common diagnosis included in the studies was breast cancer.
• The majority of the studies focused on the time period during or immediately following active cancer therapy. No study focused on palliation.

Although a consistent positive effect of physical activity on fatigue was noted using qualitative study review techniques, effect size calculations revealed no effect of physical activity on fatigue during treatment (weighted mean effect size = 0.13; 95% confidence interval [CI] [-0.06, 0.33]; p = 0.18) or after treatment (weighted mean effect size = 0.16; 95% CI [-0.23, 0.54]; p = 0.43) or on vigor/vitality during treatment (weighted mean effect size = 0.43; 95% CI [-0.07, 0.94]; p = 0.09). A large positive effect of exercise on vigor/vitality posttreatment was noted (weighted mean effect size = 0.82; 95% CI [0.05, 1.6]; p = 0.04). When fatigue and vigor/vitality were combined into one category (under the assumption that fatigue and vitality are the same attribute) and all studies were combined across treatment timing, the weighted mean effect size was still small (weighted mean effect size = 0.19; p = 0.03).

The results supported the conclusion that physical activity has a large positive effect on vigor/vitality after treatment is complete. There is some support from qualitative analysis of a consistent effect of physical activity on fatigue, although the magnitude of this effect may be too small to be clinically meaningful. The study findings also supported a preliminary conclusion that physical activity is generally well tolerated during and after cancer treatment, although the available literature does not allow conclusions to be drawn regarding adverse events from participation.

• The reviewed studies used small, self-selected samples.
• The reviewed studies were heterogeneous in terms of the outcome measures and interventions.
• The reviewed studies had gaps in the level of detail reported about individual study procedures and results.