Longitudinal changes in sports activity from pre-diagnosis to first five years post-diagnosis: a prospective Chinese breast cancer cohort study.

Background: To compare change in level of physical activity between pre-and post- diagnosis of breast cancer in Chinese women.

Methods: Based on an on-going prospective study consisting of a sample of Chinese women with breast cancer, a validated modified Chinese Baecke questionnaire was used to measure physical activity at baseline (12 months before cancer diagnosis), 18-, 36- and 60-months after diagnosis (over the previous 12 months before each interview).

Results: In our cohort of 1462 Chinese women with a mean age of 52 years, the mean level of physical activity at post-diagnosis was 9.6 metabolic equivalent of task (MET)-hours/week, which was significantly higher than that at pre-diagnosis with mean level of 5.9 MET-hours/week (P < 0.001). The mean levels of physical activity at 18-, 36- and 60-months follow-up were 9.9, 9.8 and 9.3 MET-hours/week, respectively. There was no significant difference between any two of the three follow-ups at post-diagnosis. The proportions of participant who met World Cancer Research Fund/ American Institute for Cancer Research (WCRF/AICR) recommendation before and after cancer diagnosis were both low, being 20.7 and 35.1%, respectively. Compared to pre-diagnosis, most of the patients improved or had no change on level of physical activity at post-diagnosis, with the respective proportion being 48.2 and 43.8%.

Conclusions: Adherence to current lifestyle recommendation for cancer survivors, Chinese women with breast cancer significantly increased level of physical activity level after cancer diagnosis, and such improvement was sustained to 5 years post-diagnosis. The proportion of patients who met the exercise recommendation for cancer survivors was still low. Encouraging patients on the importance of durable high level of physical activity in breast cancer survivorship is warranted.