Understanding the Drop in Cancer Cases

Smoking cessation efforts may be a big underlying factor in the recent drop seen in the country's overall cancer incidence rates.

A Mixed Bag, Doctors Say

The overall decline is mostly a function of drops in some of the most prevalent cancers. Among men, for example, lung, colorectal and prostate cancers all showed declines. Rates of breast and colorectal cancer in women also decreased.

But even among those cancers, the declines are likely less a function of one particular factor and are due more to a combination of changes in behavior and screening.

Still, noted ABC News medical editor Dr. Tim Johnson, smoking cessation likely played a yeoman's role in the downturn, particularly because it is implicated not only in lung cancer but in other cancers too.

"The most significant thing to talk about now is for people to stop smoking," he said. "There's nothing that comes close to it in terms of direct impact on cancer rates."

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Dr. John Spangler, director of tobacco-intervention programs and a professor of family medicine at Wake Forest University School of Medicine in Winston-Salem, N.C., agreed. "Many of the cancers that reported declines are smoking-related, such as lung, breast and prostate cancers. So I think this is a remarkable statement on the progress of tobacco control we have made nationally."

But there is still progress to be made on the smoking front. Indeed, Gonzales' story is not one that is generally reflected in U.S. women as a group; the rates of lung cancer in women have continued to rise, even in this latest report.

Study co-author Dr. Ahmedin Jemal, an epidemiologist with the American Cancer Society, said he expects the number of women who develop lung cancer to drop in the years to come as more women, like Gonzales, choose to kick the smoking habit. But he said more support in the form of anti-tobacco legislation and state spending on smoking prevention efforts is needed to spur progress.

"The decrease in tobacco use has provided a significant opportunity to prevent cancer," he said. "Smoking accounts for nearly one-third of cancer cases, and yet many states are not properly funding tobacco control programs."