Obesity linked to greater myeloma risk in women

Case-control and cohort studies have investigated a potential link between excess adiposity and multiple myeloma, but results have been inconsistent, Cindy K. Blair of the University of Minnesota Cancer Center in Minneapolis and her colleagues note. However, laboratory studies suggest at least two mechanisms through which the two could be related.

Adipose tissue synthesizes and secretes interleukin-6 (IL-6), which plays a role in plasma cell proliferation and survival. And insulin-like growth factor, which has been tied to obesity, can trigger proliferation of multiple myeloma cells and block their apoptosis.

Past studies have used different BMI cutoff points to gauge obesity, Blair noted in an interview with Reuters Health. To clarify the relation between multiple myeloma and obesity, she and her colleagues used several anthropometric characteristics to investigate the association, including BMI, weight, waist-to-hip ratio, and individual waist and hip measurements.

In a group of 37,083 post-menopausal women followed for 16 years, Blair and her team found that several of these characteristics conferred greater risk.

Those with a BMI of 30 or greater were 1.5 times more likely to develop multiple myeloma, while weight, waist circumference or hip circumference in the highest tertile all roughly doubled the risk. However, there was no relationship between waist-to-hip ratio and multiple myeloma risk.

A recent study found that people with a certain polymorphism in the IL-6 gene promoter had higher BMI, her team reports in the September issue of Epidemiology. "Investigating this and other gene polymorphisms could shed light on the biologic mechanisms involved in the link between excess adiposity and multiple myeloma carcinogenesis," they conclude.

Epidemiology 2005;16:691-694.