Smoking & Cancer (Contd.)

From painstaking ten-minute to half-hour microscopic examinations of each of 19,797 exquisitely thin slivers of tissue from human lungs, medical researchers reported last week that they had found the strongest anatomical evidence that heavy cigarette smoking is a potent cause of lung cancer. At the A.M.A.'s Dallas meeting, Dr. Oscar Auerbach of East Orange, N.J. told how he and a distinguished colleague, Dr. Arthur Purdy Sout (retired professor of pathology at Columbia Uni versity's College of Physicians and Surgeons), had examined the magnified tissue slides, cell by cell. Working with them were two statisticians, Dr. E. Cuyler Hammond and Lawrence Garfinkel, both of the American Cancer Society.

Virtually all previous evidence linking cigarettes with lung cancer has been based on epidemiological studies--retrospective checks on whether victims had been heavy smokers and prospective checks on whether many heavy smokers eventually died of the disease. Wanted, said critics of these studies, was anatomical evidence showing the gradual development of cancer in smokers' lungs. Dr. Auerbach's previous reports (1955 and 1957) on this development had been challenged on technical grounds. This time, his four-man team was determined to plug every conceivable research loophole.

Slicing the Tree. The pathologists removed the whole breathing apparatus ("tracheobronchial tree") from the bodies of 402 men who died in Veterans Administration Hospital in East Orange and in eleven New York hospitals (mainly in nonindustrial towns to reduce bias that might result from air pollution). It turned out that 63 of the men had died of lung cancer and 339 from other causes, but the pathologists did not know this until after they had finished their findings. Each "tree" was cut into 208 portions and embedded in paraffin. Fifty-five of these portions, chosen for microscopic study, were then sliced three microns thick.

The pathologists were looking for changes in the cells, along a spectrum from normal through slightly abnormal to precancerous and finally cancerous. There were many abnormalities that the pathologists rated as probably too minor to be significant; also, many patients had died of pneumonia or other lung diseases. Even including these cases, the pathologists found atypical cells in only 3.8% of slides from nonsmokers and 10.9% of those from occasional cigarette smokers.

Dormant Danger. But even moderate regular smoking went with a startling rise in the chart for atypical cells: for men who smoked less than half a pack daily, it soared to 90.6% of the slides. In the half-pack to one-pack bracket, it was 97%; for one to two packs, 99.3%; more than two packs, 99.6%; and in lung cancer victims, 99.7%.

For the various stages of progression toward overt cancer, the graphs showed a similar increase with heavier smoking. Cancer-type cells lying dormant but presumably capable of erupting into fatal disease were not found in any nonsmokers or occasional smokers. But they occurred in .3% of slides in the group smoking less than half a pack daily; .8% in the half-pack-to-a-pack group; 4.3% in the one-to-two-packs group; and 11.4% of slides from men smoking more than two packs.

If challengers of the link between smoking and cancer want (as they say) evidence based on people instead of statistics, this seems to be it.

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