Previous reports citing the increased risk of lung cancer in heavy smokers of cigarettes "are not exaggerated, but are indeed conservative," according to Dr. Leonid S. Snegireff, associate professor of Cancer Control at the Harvard School of Public Health.

Dr. Snegireff, speaking before a scientific session of the American Pharmaceutical Manufacturers' Association in New York, reported on a five-year study of the epidemiology (mass behavior) of lung cancer. The cancer expert spoke on "Lung Cancer and Smoking" in a symposium at the Waldorf Astoria Hotel yesterday afternoon.

Dr. Snegireff also presented evidence, taken from a Public Health School survey, that a number of physicians and dentists in Massachusetts have stopped smoking within the last five years.

As a part of the five-year survey conducted by the School of Public Health, Dr. Snegireff and his associates have examined 16 studies conducted in the United States and Europe which link lung cancer and cigarette smoking.

"Smoking," the scientist said, "is the leading important feature that the vast majority of the lung cancer patients have in common. We owe it to ourselves," he continued, "to ponder carefully whether as individuals we wish to smoke cigarettes and run the risk of cancer."