Women's Health Watch
NOVEMBER 02, 2010
The Renewed Debate on Mammograms
The question of when to begin screening for breast cancer in women is still a matter of debate. A new trial, recently published in the journal Cancer, looked at the recommended age for starting mammograms and the effect the tests had on preventing invasive breast cancer.
The large Swedish study, touted as the largest epidemiological study of mammography in the age group of 40 to 49 years, showed that mortality reduction was much larger than previously reported in women who received mammograms between the studied ages. Just last year, the United States Preventive Services Task Force (USPSTF) changed the recommended age for women to begin receiving mammograms from age 40 to 50 years. As opposed to the USPSTF’s meta-analysis of 8 studies, which showed only a 15% risk reduction in women who received mammograms between the ages of 39 and 49 years, this study calculated the risk reduction from more than 1 million women to be 29% in those who received mammograms during their 40s.
Although not randomized, the study highlighted the disparity in disease severity between women who begin receiving mammograms at age 50, which was typical in some Swedish counties, and those who begin at age 40 years. Interestingly, greater benefit was seen among women aged 45 to 49 years than in women aged 40 to 44 years.
Currently, the USPSTF is the only American organization that recommends beginning screening at age 50 years. Other US organizations, including the American Congress of Obstetricians and Gynecologists, the American Cancer Society, the National Comprehensive Cancer Network, and the American Medical Association, recommend screening to begin at age 40 years.
Possible Link Found Between Obesity and Infertility
Insulin resistance has always been thought to be the main mechanism behind infertility in obese women. Researchers from Johns Hopkins University have recently provided some evidence that could change the understanding of insulin’s role in infertility. The study, published in the September 8 issue of Cell Metabolism, generated pituitary-specific insulin receptor knockout, or PitIRKO, in mice, and compared their fertility to wild-type mice in the presence of obesity. The scientists found that the obese mice that still had the pituitary insulin receptor intact were infertile, while PitIRKO mice retained near-normal fertility.
This finding goes against the conventional wisdom that insulin resistance is the key factor causing infertility in obese women. Women with polycystic ovarian syndrome (PCOS) are resistant to and have higher blood concentrations of insulin. Upon insulin stimulation, the pituitary gland secretes luteinizing hormone (LH), which in excess promotes anovulation and infertility. Women with PCOS have high concentrations of LH. Although metabolic tissues such as adipose, liver, and muscle may become resistant to insulin in the presence of obesity, it seems that the pituitary gland retains its insulin sensitivity, and in a hyperinsulinemic state, more LH is secreted, thus promoting anovulation.
While the goal of PCOS treatment has been to promote insulin sensitivity, primarily with metformin therapy, blocking the insulin receptor on the pituitary gland may prove to be a successful therapy as well.
Home-Based Exercises Decrease Risk of Hip Fractures in Elderly Women
In a randomized trial published in the Archives of Internal Medicine in September, researchers from Finland found that home-based exercises—including daily stretching and weight-bearing exercises— reduce important risk factors for falls and fractures in elderly women with osteopenia. The study randomized 160 women with hip and radius osteopenia to either the experiment group or the control group and monitored them from 1997 to 2004.
In the experiment group, women received supervised exercises for 6 months followed by home exercises for another 6 months of each year. Fracture data were obtained annually and at followup for all 160 women enrolled in the trial. In comparison with the control group (n = 76), the exercise group (n = 84) demonstrated a significant gain in mean leg strength, maintenance of gait speed at baseline, and decreased change from baseline in the 2-minute walk test score.
Raija Korpelainen, PhD, lead author of the study, claims that this study is “the first to report the long-term effect of exercise on fractures in elderly women with osteopenia.” Nevertheless, the researchers warn that to provide the best evidence for the effect of exercise in preventing fractures, more randomized trials, including population-based studies that rely on larger sample sizes, will be needed. Since fall-related fractures are associated with increased morbidity and mortality in the elderly population, methods to decrease the risk of fractures are greatly needed.