NEW YORK (Reuters Health) - Smoking and heavy alcohol use may curb the likelihood of survival among men diagnosed with cancer, researchers from South Korea report.

There is some evidence that these "cancer risk factors" boost mortality among cancer patients, Dr. Young Ho Yun of the National Cancer Center in Goyang and colleagues note. But to date no one has investigated how having these risk factors before cancer is diagnosed influences survival afterwards.

Yun's team looked at data from 14,578 male cancer patients, all of whom had data on their pre-diagnosis health risk behaviors on record. They were followed for an average of about nine years after their cancer diagnosis.

Men who had been smokers were at greater risk of dying from any type of cancer than non-smoking cancer patients, the researchers found. There is evidence that smokers are less likely to undergo cancer screening tests such as colonoscopy, so they may be diagnosed with cancer later on when it is more difficult to treat, the researchers note. Cigarette smoking itself, they add, could also make tumors grow more aggressively.

Heavy drinkers were more likely to die from head and neck or liver cancer than non-drinkers with either type of cancer, and the risk rose in tandem with the amount of alcohol consumed. Drinking alcohol may increase tumor aggressiveness, the researchers say, or make people less likely to comply with treatment recommendations.

Men who were resistant to the effects of the blood-sugar-processing hormone insulin, which is a warning sign of diabetes, were also more likely to die after a cancer diagnosis.

However, the researchers found, people with a high body mass index (a measure of weight in relation to height) were at lower risk of death from cancer overall, and from head and neck or esophageal cancer specifically. Heavier patients might fare better after a cancer diagnosis because they are better nourished and thus more able to survive the rigors of treatment, the researchers note.

"Our findings suggest that groups at high risk of cancer need to be educated continually to improve their health behaviors -- not only to prevent cancer, but also to improve prognosis," the team concludes.