Paternal smokers' cancer legacy.

Children whose fathers smoke face a significantly higher risk of developing cancer than children of nonsmoking dads, according to a new Chinese study.

Cigarette smoke is a rich source of free radicals. These chemically reactive molecular fragments can damage DNA, making affected cells more susceptible to cancer (SN: 2/22/97, p. 126). Most studies looking into the role of parental smoking in childhood cancers have focused on mom's habits. Because smoke-generated free radicals can also alter DNA in sperm, an international team of researchers investigated cigarettes' potential genetic fallout in 1,284 Shanghai families in which the mother didn't smoke. In half of these families, the father did.

By age 5, children whose fathers had smoked an average of a pack a day or more for 5 years prior to conception faced a 70 percent higher risk of developing cancer than did the offspring of nonsmoking men. Bu-Tian Ji of the Shanghai Cancer Institute and his colleagues report their findings in the Feb. 5 Journal of the National Cancer Institute.

Though they cannot rule out some contribution from passive smoke, Ji and his coworkers note that if this were the major factor, the amount a man had smoked prior to his child's conception shouldn't affect risk much. In fact, however, the more and longer a man had smoked prior to that conception, the greater the risk that his preschooler would develop cancer.

Certain malignancies were more likely to develop than others. Youngsters of the men who had smoked the most and longest proved 4.5 times as likely to develop lymphoma, almost 4.0 times as likely to develop acute lymphocytic leukemia, and 2.7 times as likely to get brain tumors.