Science / Medicine : Former Smokers and Cancer

A study of 34,000 Seventh-day Adventists in California has found that former smokers have twice the leukemia rate of people who never smoked and three times the rate of multiple myeloma. The study also found that the risks for both cancers increased in a classic “dose-response” fashion, with highest risks associated with the longest duration of smoking and greatest number of daily cigarettes.

Paul Mills and his colleagues at Loma Linda University found 46 cases of leukemia among those in the study and 23 cases of myeloma. When they compared former smokers and never-smokers, they discovered a “statistically significant” link between both diseases and smoking, the researchers reported in the Journal of the National Cancer Institute.

In an editorial accompanying the study, Clark Heath of the American Cancer Society noted that cigarette smoke contains the chemical benzene and is a source of ionizing radiation--and that both benzene and radiation are known causes of leukemia in humans.