Young women with high body fat have a reduced chance of developing breast cancer before the menopause, according to scientists from the National Institutes of Health and their coworkers. The findings, published online in the JAMA Oncology journal, could help researchers better understand the role of breast cancer obesity.
"It is well known that women, especially after menopause, are gaining weight and are at an increased risk for postmenopausal breast cancer," said Dale Sandler, Ph.D., co-senior author and Head of the Department of Epidemiology at the National Institute of Environmental Health Sciences (NIEHS), part of the NIH. "Our finding that the risk of breast cancer in overweight premenopausal women is not increased and is actually decreasing suggests the possibility that various biological mechanisms are responsible for the development of breast cancer in younger women."
said before the development of breast cancer. Englisch: dermis.multimedica.de: 80 / dermisroot … iagnosep.htm. Englisch: dermis.multimedica.de: 80 / dermisroot … iagnosep.htm fully evaluate a study. She added that previous studies suggested that risk factors for breast cancer in younger women are not the same as in older women.
To understand breast cancer risk in women who have not gone through menopause, Sandler and other researchers formed the premenopausal breast cancer collaborative group. The international team collected data from 19 different studies, including 758,592 women from around the world. The approach allowed the team to identify risk factors and patterns that would be difficult to detect with a smaller number of women.
Participants in the joint group studies were between 18 and 54 years old at the start of the study follow-up. Volunteers for each individual study completed several questionnaires, including body size, weight, and other health-related factors. Using this information, researchers assessed the risk of developing breast cancer in terms of body mass index (BMI) in the following age groups: 18-24, 25-34, 35-44, and 45-54. BMI is one way to measure the amount of body fat. In total, 13,082 participants or 1.7 percent developed breast cancer during the observed periods.
The researchers found that the relative risk of premenopausal breast cancer was reduced by 12-23 percent for each increase in BMI in five units, depending on age. The strongest effect was observed in terms of BMI at the age of 18 to 24 years, with very obese women in this age group developing 4.2 times less premenopausal breast cancer than women of low BMI at the same age.
While Sandler and her colleagues are not sure why young, premenopausal women with a high BMI appear to be protected from breast cancer, she warns that young women should not intentionally gain weight to reduce their risk of breast cancer.
"There are so many health risks of overweight or obesity," Sandler said. "We still believe it is important for women to maintain a healthy weight throughout their lives."