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Excerpts from Common Genetic Trait Tied to Lung Cancer Risk; Exposure to Secondhand Smoke Poses Bigger Threat Among Women Lacking Protective Enzyme

By Marc Kaufman, Washington Post [12/07/99]

White women with a common genetic deficiency are at much greater risk from secondhand smoke than women without it, a research team at the National Cancer Institute has found.

In a study of 106 white female nonsmokers with lung cancer from Missouri who had been exposed to substantial amounts of secondhand smoke, the researchers found that a significantly higher than expected number of the women did not have a functioning GSTM-1 gene. This led the researchers to conclude that people with this deficiency were at a higher risk of developing lung cancer than others.

The results "indicate that [secondhand smoke] exposure may more than double the risk of lung cancer for nearly half of the white women in Western nations," the study says.

The gene being studied is one of a group involved in the creation of cancer-killing enzymes. It is missing or impaired in roughly half of all whites and Hispanics but is deficient in only about 30 percent of blacks.

Scientists have known for some time that people exposed to secondhand smoke are at a higher risk of developing lung cancer than those who are not. The importance of the new finding, the researchers said, is that the risk was found to be much greater than expected in the white population without the GSTM-1 gene and considerably less than expected in the half with the gene.

The study was published in this month's Journal of the National Cancer Institute. In an accompanying editorial, Clarice Weinberg of the National Institute of Environmental Health Sciences said the study was important but needed to be followed up because there was no randomized control group.