Do Exercise Oncology Guidelines Have To Be Met To Obtain Improvements In Breast Cancer Outcomes?

Abstract

PURPOSE: To explore whether compliance to weekly exercise targets predicts improvements in outcomes in women with breast cancer who participated in SAFE ACTRN12616000954426. METHODS: Physically inactive breast cancer survivors (stage II-IV; mean age 50.1±9.0) were randomised to frequent- (20 sessions, n=30) or limited (5 sessions, n=30) supervision with an exercise physiologist during a 12-week individually-tailored exercise intervention. The weekly exercise target was consistent with international guidelines of 600 MET minutes including at least 2 resistance exercise sessions. Exercise undertaken (mode, frequency, minutes, intensity) was recorded weekly and used to calculate MET mins. Exercise compliance was defined as 1) average weekly volume ≥ weekly target or 2) weekly target met in ≥ 80% of weeks. Multivariable regression analyses (adjustment for age, disease stage, BMI and group allocation) were used to evaluate whether exercise compliance predicted change between pre- and post-intervention in physical health (PROMIS global), aerobic fitness (6-minute walk test) and strength (YMCA bench press). RESULTS: 63% and 27% of sample (n=60) were compliant when defined by average weekly volume and ≥80% of weeks, respectively. Having an average weekly exercise volume that was ≥ weekly target predicted a clinically meaningful improvement in physical health (Δ±SE: 7.2±1.0 p<0.01), aerobic fitness (59.8±11.4 metres, p<0.05) and upper body strength (11.4±2.2, p=0.25). Meeting weekly targets ≥80% of intervention weeks did not predict change in outcomes (p≥0.05). CONCLUSION: These findings suggest that for achieving improvements in outcomes, it is important to ensure the volume of exercise undertaken over time meet targets, but that achieving weekly exercise volume targets on any given week is not. This represents reassuring evidence, particularly for patients who have short term declines in exercise undertaken as a consequence of accommodating fluctuating treatment-related symptoms, surgery requirements or new life circumstances.