Smoking and kidney cancer risk

— Jay D. Hunt, Ph.D, International Journal of Cancer, 10 March 2005. Reuters Health, reprinted with permission.

Pulling together data from 24 studies conducted since the 1960s, an international research team found that the risk of kidney cancer was 38 percent higher among people who had ever smoked versus those who had never picked up the habit.

And the more smokers had puffed over a lifetime, the greater the risk to their kidneys — a so-called dose-response relationship that supports a direct link between smoking and kidney cancer.

In fact, Hunt told Reuters Health, before conducting this study, he had been skeptical that the relationship between smoking and kidney cancer was real — in part because past studies have yielded conflicting results. Even when an association has been found in individual studies, he noted, it has generally been “modest.”

Hunt and his colleagues culled data from 24 previous studies conducted in North America, Europe and Australia, and used a mathematical model to estimate the overall risk of kidney cancer associated with various levels of smoking.

The researchers found that among men, those with a history of smoking were more than 50 percent more likely to develop kidney cancer than those who had never smoked. Among women, smokers had a 22 percent greater risk of developing the disease. Even light smokers — those who averaged fewer than 10 cigarettes a day — were 60 percent more likely than non-smokers to develop the disease. The odds were still higher with moderate smoking, defined as 10 to 20 cigarettes per day.

These findings diverge from previous estimates, according to Hunt, who said that modest levels of smoking have typically been thought to carry little to no risk of kidney cancer.

There was, however, a bright spot in the findings — namely, that the risk of kidney cancer appears to keep dropping in the years after a person kicks the smoking habit. The risk of the disease was substantially lower among former smokers who had abstained for 10 years or more, compared with those who had quit more recently.

This trend, Hunt said, can definitely be seen as “good news” for former smokers.

Editor’s note: VHL itself is a risk factor for kidney cancer. People with VHL who smoke generally have more tumors and faster tumor growth. (Walther et al.)

As printed in the VHL Family Forum 13:1, April 2005. For permission to reprint, please contact VHL Family Alliance, editor@vhl.org. Further information is available from the VHL Family Alliance, info@vhl.org.