Men who smoke heavily are nearly twice as likely as nonsmokers to die from a common form of leukemia, concludes a report by the University of Edinburgh. The analysis, based on a previous study of 248,046 U.S. veterans, offers the firmest link yet between cigarette consumption and the disease. The finding could add leukemia to the already lengthy list of suspected health risks from smoking. The report in tomorrow's British Medical Journal "may well have an emotional impact on some people who are vacillating" about quitting smoking "and for one reason or another have a fear of leukemia," suggested Nicholas Wald, an epidemiologist at the Medical College of St. Bartholomew's Hospital here. "The balance of evidence suggests that smoking may cause leukemia," Dr. Wald wrote in an accompanying commentary on the analysis, which was conducted by University of Edinburgh epidemiologist Leo Kinlen. Dr. Kinlen, who directs the university's Cancer Epidemiology Unit, examined leukemia deaths from a U.S. study that had tracked veterans' smoking between 1954 and 1969. The earlier study tallied overall deaths from various causes, including 723 deaths due to leukemia. Dr. Kinlen found veterans who had smoked more than 21 cigarettes a day were the most likely to die from myeloid leukemia, the most common form of the disease in middle-aged people. These heavy smokers had a 93% greater chance of developing fatal leukemia than the veterans who never had smoked. For those smoking between 10 and 20 cigarettes a day, the increased risk was 75%. And men using fewer than 10 cigarettes daily were 31% more likely to die from leukemia than nonsmokers, according to the report. Previous studies have observed higher death rates from leukemia among smokers, but either involved fewer patients or didn't compare amounts smoked with incidence of the disease. For this reason, leukemia "has in general not been regarded as a a malignancy related to smoking," Dr. Kinlen wrote. The latest analysis doesn't prove a causal link, Dr. Kinlen noted in a phone interview. But "it is the best evidence to date that the relationship is genuine." If the link is causal, an editorial in the medical journal said, "then smoking is a more important cause of leukemia in adults than all other known causes combined." Current known causes include radiation and exposure to the chemical benzene. Leukemia is fairly rare. An estimated 18,100 Americans will die from it this year, making the disease the fifth-greatest cause of cancer deaths. But leukemia represents the third-leading cause of death in U.S. children, behind accidents and birth defects, according to the American Cancer Society.
<SUM TYPE="PERDOC" SIZE="100" DOCREF="WSJ880909-0170" SELECTOR="F" A study of 248,046 US veterans showed that heavy smokers ( between 10 and 20 cigarettes a day) had a 31% greater chance of developing fatal leukemia than those who never smoked. For smoking more than 21 cigarettes a day the increased risk was 75% , and 93% for fewer than ten cigarettes a day. The latest analysis doesn't prove a causal link, but an editorial in a the Medical College of St. Bartholomew's Hospital said that if the link is causal, "then smoking is a more important cause of leukemia than all other known causes combined." Leukemia is the third leading cause of death among US children and fifth overall in cancer deaths.