Vital Signs: Sept. 10

Thursday, September 10, 2009

Habits may lower risk

of breast cancer

Women can cut their risk of breast cancer by almost half if they watch their weight, exercise daily, breast-feed their babies and limit alcoholic beverages, according to a new report by the American Institute for Cancer Research.

The report updates a 2007 review of more than 800 studies, adding information from 81 new studies, said Susan Higginbotham, director of research for the institute.

The preventive steps include maintaining a healthy body weight, engaging in 30 to 60 minutes of physical activity a day, breast-feeding and limiting alcohol to one drink a day.

The role of hormones in breast cancer, including both postmenopausal hormone therapy and oral contraceptives, was not examined.

To reduce the risk of cancer generally, Higginbotham said, diets should be mostly plant-based, emphasizing fruits, vegetables, beans and whole grains and limiting red meat.

The recommendations are based on observational studies that have found associations between the behaviors and a reduced risk of breast cancer, but such studies do not prove a cause-and-effect relationship.

Clinical trials often

are not registered

Many researchers are ignoring a 2005 requirement that they register proposed clinical trials in a government database as a condition for publishing their results in medical journals. And the journals are publishing the papers anyway, a new study reveals.

The study, a review of 323 articles published last year in leading medical journals, found that only 147 of the clinical trials — 45.5 percent — were properly registered before the end of the trial in a way that clearly stated the main outcomes being assessed. Even among the articles that were registered, almost a third had discrepancies between the outcomes described in the registry and the ones ultimately reported.

Of the trials that were not registered properly, 89 — more than half — were never entered in the National Institutes of Health's clinical trials registry. The report appears in the Sept. 2 issue of The Journal of the American Medical Association.

Moher added that bias could easily be introduced when investigators changed the primary outcome they were measuring — moving the goalpost, so to speak. That might happen, for example, if a clinical trial is designed to determine whether a drug increases survival rates but investigators change the primary outcome to assessing if the drug improves quality of life.

Seeing a family benefit from obesity surgery

Children born to women who had bariatric surgery for obesity may face a lower risk of severe obesity themselves, a study suggests.

The study, of 111 children born to 49 mothers who had a type of weight-loss surgery called biliopancreatic diversion, found that babies born after the operation had lower birth weights than those born before, and their risk of becoming severely obese as children was one-third the risk of those born before. Only 11 percent of the children born after surgery were severely obese, compared with 35 percent of the others.

Children born after the operation also had better cholesterol levels and improved insulin sensitivity, indicating they might be less likely to develop heart disease and diabetes later in life, the researchers found.

Two notes of caution about the paper, to be published in The Journal of Clinical Endocrinology & Metabolism: The findings are based on observation of the children, and bariatric surgery can lead to other complications.

like anemia, malnutrition, loss of bone density and, rarely, death.

An author of the paper, Dr. John Kral, a professor of surgery and medicine at SUNY Downstate Medical Center in Brooklyn, said the benefits to the children might be due to metabolic and hormonal changes in the wombs of women who have had the operation.