Studies Indicate a Link between Body Weight, Exercise, Lifestyle and Breast Cancer

In case you’re not convinced yet, three new studies have given more evidence that doing your best to stay active and keep your weight in check really does make a difference:

Trial shows it’s time to get down to business and double up on our exercise!

In an article published July 16th in JAMA Oncology, Christine M. Friedenreich, PhD and her co-authors shared the results of a 1-year clinical trial which focused on the effects of 300 vs 150 minutes a week of moderate to vigorous aerobic exercise on body fat in postmenopausal women.

The Breast Cancer and Exercise Trial in Edmonton, Alberta took place from June 2010 through June 2013. Participants were 400 inactive postmenopausal women with a body mass index between 22 and 40.

The authors, led by Dr. Friedenreich, conclude: “In previously inactive postmenopausal women, a 1-year prescription of moderate to vigorous exercise for 300 minutes/week was superior to 150 minutes/week for reducing total fat and other adiposity (fat) measures, especially in obese women. These results suggest additional benefit of higher-volume aerobic exercise for adiposity outcomes and possibly a lower risk of postmenopausal breast cancer.”

Average reductions in total body fat were 1 kg (1% of body fat) larger in the 300-minute exercise group compared with the 150-minute group.

Decreases were also larger for the following measures in the 300-minute group:

• Subcutaneous abdominal fat
• Total abdominal fat
• BMI
• Waist circumference
• Waist-to-hip ratio.

The authors conclude: “A probable association between physical activity and postmenopausal breast cancer risk is supported by more than 100 epidemiological studies, with strong biologic rationale supporting fat loss as an important (though not the only) mediator of this association.

“Our findings of a dose-response effect of exercise on total fat mass and several other adiposity measures including abdominal fat, especially in obese women, provide a basis for encouraging postmenopausal women to exercise at least 300 minutes/week, longer than the minimum recommended for cancer prevention.”

Related: BC survivors more likely to gain weight

It’s definitely not fair, but a recent study discovered that women who survive breast cancer are more likely to gain weight over the following years than women who have not had cancer. Women treated with chemotherapy are at particular risk for weight gain, as are women with a family history, according to researchers from Johns Hopkins Kimmel Cancer Center in Baltimore, MD.

Among both the breast cancer survivors (46.9%) and cancer-free women who had a family history of breast cancer (55.1%), the study found a high prevalence of overweight participants.

Previously, studies have found that women who have survived breast cancer and go on to gain weight are at increased risk of having their cancer return. In addition, weight gains of 11 pounds or more have been linked with an increased risk of cardiovascular disease.

In the new study, published in the journal Cancer Epidemiology, Biomarkers & Prevention, the Johns Hopkins team recruited 303 breast cancer survivors and 307 cancer-free women between 2005 and 2013. All women completed a questionnaire at the start of the study, and they were followed-up four years later. About a quarter of the women in the study were premenopausal and the majority of the participants were white.

The researchers found that breast cancer survivors gained significantly more weight during the four year follow-up period than women who had not had cancer. Breast cancer survivors gained an average of 3.6 pounds more in weight.

Among women in the study who had been diagnosed with cancer during the last five years of the study period, 21% put on at least 11 pounds over four years, while only 11% of the cancer-free women put on this much weight over four years.

Women who had completed chemotherapy within five years of the study were found to be 2.1 times as likely as women who had not had cancer to gain at least 11pounds during the study.

After taking into account other factors that may have influenced weight, such as age, menopausal status and level of physical activity, the association between cancer history and weight gain remained strong.

According to Kala Visvanathan, an associate professor of epidemiology at the Johns Hopkins Bloomberg School of Public Health and director of the Clinical Cancer Genetics and Prevention Service at the Kimmel Cancer Center:

“There is limited data on weight change in breast cancer survivors, including those at higher risk for the disease compared to the general population. A lot of studies have focused on breast cancer survivors alone, so we don’t get a sense of whether women without cancer gain more or less weight, or whether the gain is due to the cancer or the treatment.”

The team will continue to follow-up with the group every three to four years to investigate the long-term weight changes of the women.

Visvanathan stresses that the authors are not suggesting any weight gain intervention at the time of chemotherapy. “But we are suggesting that oncologists, internists or anyone treating breast cancer survivors, including those with a family history of the disease, could help them monitor their weight over the long term.”

Sedentary lifestyles don’t do us any favors, either

woman with a According to a study just published in Cancer Epidemiology, Biomarkers, and Prevention, women who spend much of their leisure time sitting may be at an increased risk of multiple myeloma, breast and ovarian cancers.

The perceived link between sitting time and cancer risk is relatively unstudied, despite extensive evidence suggesting a link between cancer prevention and physical activity. However, research is increasingly investigating the negative consequences of spending a lot of time sitting, since our down time has increased tremendously in recent decades.

The new study analyzed data from 69,260 men and 77,462 women who had not been diagnosed with cancer and who were enrolled in the American Cancer Society Cancer Prevention Study II Nutrition Cohort.

During this study, between 1992 and 2009, 18,555 men and 12,236 women were diagnosed with cancer.

The authors of the study found that the women in the study were more likely to develop multiple myeloma, invasive breast cancer or ovarian cancer if they spent longer times sitting. However, they did not find a link between the length of time men spent sitting and their risk of cancer.

“Longer leisure-time spent sitting was associated with a higher risk of total cancer risk in women, and specifically with multiple myeloma, breast and ovarian cancers, but sitting time was not associated with cancer risk in men. Further research is warranted to better understand the differences in associations between men and women.”