Study on Weight Loss and Breast Cancer Risk in Postmenopausal Women

Background

A recent study investigated the potential association between weight loss and breast cancer risk in postmenopausal women. Research has established that obesity significantly increases the likelihood of developing breast cancer in this demographic. In the United States, roughly one-third of postmenopausal women are classified as obese. Since weight loss can be a modifiable factor, it may offer a pathway to lower breast cancer incidence.

Inconsistent Findings in Previous Research

Despite the potential benefits, the relationship between weight loss and breast cancer incidence remains unclear. Various studies have yielded inconsistent results. For instance, clinical trials conducted by The Women’s Health Initiative, involving 67,142 postmenopausal women, found no significant link between weight loss and breast cancer incidence. This lack of clarity complicates public health messaging aimed at encouraging weight loss as a means of reducing breast cancer risk among obese or overweight postmenopausal women.

Impact of Weight Loss Programs

A national non-profit weight loss initiative in the United States, Take Off Pounds Sensibly, has demonstrated that participants can achieve and maintain a weight loss of 5% or more for several years. Such modest weight loss has been associated with various health benefits, including reduced risks of heart disease, type 2 diabetes, and less severe obstructive sleep apnea.

New Study Findings

Building on the insights from the aforementioned program, researchers in the United States launched a study to explore whether a small amount of weight loss correlates with breast cancer incidence among participants in the Women’s Initiative Health Observational Study. The results were published in the journal Cancer.

Study Methodology

The study analyzed data from 61,335 postmenopausal women who had not previously been diagnosed with breast cancer and had normal mammogram results. Researchers calculated the participants’ body mass index (BMI) by measuring their weight and height at the start of the study and again at year three. Changes in weight were classified into three categories: stable (less than 5% weight loss), loss (5% or more weight loss), and gain (5% or more weight gain). Participants also self-reported any intentional weight loss after the third year.

Results and Implications

After an average follow-up period of 11.4 years, 3,061 cases of breast cancer were reported. The study revealed that women who lost weight had a significantly lower risk of developing breast cancer compared to those whose weight remained stable. However, no substantial difference was observed among women who intentionally lost weight. Additionally, weight gain did not show a direct association with breast cancer risk.

Considerations and Limitations

It is important to interpret these findings cautiously. Weight gain was associated with a higher incidence of triple-negative breast cancer, a rare type of breast cancer that grows without hormonal support. The researchers acknowledged limitations, including the fact that weight measurements were only taken at the beginning of the study and at year three. Nevertheless, self-reports indicated that most of the weight loss was maintained by year six.

Conclusion

The findings from this study suggest that weight loss among postmenopausal women is linked to a reduced risk of developing breast cancer. Therefore, lifestyle interventions that promote weight loss through increased physical activity and healthier dietary choices may be beneficial for postmenopausal women in lowering their breast cancer risk.

Reference

Chlebowski RT, Luo J, Anderson GL, Barrington W, Reding K, Simon MS, Manson JE, Rohan TE, Wactawski-Wende J, Lane D, Strickler H, Mosaver-Rahmani Y, Freudenheim JL, Saquib N, Stefanick ML. Weight loss and breast cancer incidence in postmenopausal women. Cancer. 2018 Oct 8. doi: 10.1002/cncr.31687.