Fat loss with exercise confers benefits for breast cancer biomarkers

A year-long course of supervised exercise intervention does not appear to yield large positive effects on breast cancer biomarkers in physically inactive menopausal women, although greater fat loss with exercise does lead to more favourable biomarker trends, according to data from the Breast Cancer and Exercise Trial in Alberta (BETA).

The 24-month BETA study randomized 400 cancer-free, postmenopausal women to intervention groups prescribed moderate–vigorous aerobic exercise, 5 days/week (3 days/week supervised) for 30 minutes/session (moderate) or 60 minutes/session (high) for 12 months. All participants were required to continue with their usual diet.

After 12 months of no intervention, 24-month fasting blood samples were obtained for 84.0 percent and 82.5 percent of participants in the moderate and high groups, respectively (n=333/400).

There were no changes observed in the 0–24- or 12–24-month biomarker profiles between the high and moderate exercise groups. The high:moderate ratio of mean biomarker change ranged between 0.97 and 1.06 (p-all>0.05).

However, biomarker profiles were more favourable for participants who achieved greater than the median fat loss during the trial.

Analysis by intervention group revealed most changes in the following biomarkers high sensitivity C-reactive protein, insulin, sex hormone binding globulin (SHBG), oestradiol, although the improvements rebounded after the trial had ended. However, the only biomarkers to rebound significantly in women who lost more than the median amount of fat were SHBG and oestradiol.

The present data lend support to the hypothesis that fat loss exerts an independent effect on concentrations of breast cancer biomarkers, researchers said.