Obesity a risk factor for multiple myeloma

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An obese person is more likely than a lean person to develop multiple myeloma, as per scientists from Brigham and Womens Hospital, Harvard Medical School, and Harvard School of Public Health. Their findings indicate that Body Mass Index (BMI) a statistical measure that scales weight to height provides an indicator for ones risk of developing multiple myeloma, a cancer of the blood cells that produce antibodies. Multiple myeloma currently affects more than 50,000 people in the U.S., and the five-year survival rates of the cancer are below 40 percent.

The study, reported in the recent issue of Cancer Epidemiology, Biomarkers & Prevention, a journal of the American Association for Cancer Research, takes its data from over 100,000 participants in the on-going Nurses Health Study and Health Professionals Follow-up Study, two similar large-scale studies. The study findings were similar to those from previously published studies that included smaller numbers of multiple myeloma patients, and/or were based on a one-time recording of height and weight.

I find the results of these studies encouraging, since they show consistent results about the first risk factor for multiple myeloma that people can actually modify, said the studys lead author Brenda M. Birmann, Sc.D., a researcher in the Department of Medicine at Brigham and Womens Hospital and Harvard Medical School. Treatment options for this disease are improving, but it is also important to identify risk factors that could be modified. We would like to learn how to prevent its occurrence.

The Brigham and Womens Hospital-based Nurses Health Study has followed the health of female registered nurses since 1976, and the Health Professionals Follow-up Study, based at Harvard School of Public Health, has followed males from several health professions since 1986. These studies recorded height, weight and physical activity for each person enrolled, as well as diet, medications, smoking habits and other health behaviors, and has updated that information every two to four years. Of the 136,623 participants who qualified for their study protocol, Birmann and her colleagues confirmed 215 cases of multiple myeloma.

Body Mass Index (BMI) is computed by dividing a persons weight by the square of their height. A BMI between 18.5 and 25 is considered optimal, a BMI of 25-29 is considered overweight, and a BMI of 30 or higher is considered obese.

The association between BMI and multiple myeloma was strongest among men with a BMI of 30 or more. When compared with leaner men (those with a BMI below 22), obese men, the scientists said, were over twice as likely to develop multiple myeloma. The effect was less pronounced among overweight or obese women, yet those women also had an increased risk.

The study also looked at whether regular exercise is correlation to risk of multiple myeloma. There was not a clear effect of exercise on risk, eventhough the results among women suggested that those who exercise more might have a lower risk. We cannot say with certainty that exercise reduces the risk of multiple myeloma, but there is ample evidence that regular exercise offers a number of other health benefits, Birmann said.

The study findings do show, however, that the effect of BMI on risk of multiple myeloma is separate from any possible effect of physical activity.

As per Birmann, prior research has identified possible biological links between obesity and multiple myeloma. For example, adipocytes, cells found in fat tissue, produce a cell signal, called interleukin-6 (IL-6), which promotes the immune systems inflammation response. In obese people, this can cause an overproduction of IL-6, which in turn creates a cellular environment that sustains multiple myeloma. The IL-6 chemical pathway is one possible way obesity could influence the risk of developing diseases like cancer or cardiovascular disease, but the answer might also lie in other relationships between obesity and cancer, Birmann said.

Further research, she said, will uncover more about the relationships between obesity and cancers such as multiple myeloma. The scientists believe their findings may lead to examination in greater detail of the BMI/multiple myeloma link, including the role of IL-6 and other chemical signals, energy metabolism, and other risk factors such as weight change or weight cycling.


Posted by: Janet    Source