Physical activity in a German breast cancer patient cohort: one-year trends and characteristics associated with change in activity level.

BACKGROUND: Physical activity (PA) is increasingly discussed as concomitant therapy after breast cancer diagnosis and can add to the alleviation of therapy- and disease-related symptoms. The objectives of this study were to describe PA behaviour in the course of breast cancer and to identify factors associated with change in PA.
METHODS: 1,067 German postmenopausal breast cancer patients were asked about their PA behaviour before breast cancer diagnosis, during therapy and 1year after surgery. MET-hours per week (MET=metabolic equivalent) were calculated based on quantitative information about walking, bicycling for transportation purposes and sports by multiplying the average hours per week spent at each activity with an individual intensity score. Factors associated with change in MET·h/week in the course of breast cancer were identified using multiple linear regression.
RESULTS: Median PA decreased significantly during therapy from 36 to 14MET·h/week (p<.001). Patients treated with chemo- and/or radiotherapy had a stronger decline in PA compared to patients without adjuvant therapy or those treated only with hormones (adjusted β=-9.73 to -13.54). The presence of medical risk factors (β=-5.56) was also associated with a decrease of PA during therapy. In contrast, participation in rehabilitation (β=7.62) was associated with an increase of PA after therapy.
CONCLUSION: In the light of the drastic decline in PA during therapy, programs promoting PA seem obligatory for all breast cancer patients. Patients treated with chemo- and/or radiotherapy and those with medical risk factors should particularly be assisted in reaching recommended activity levels by targeted interventions during and after therapy.