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That smoking raises the risk for throat cancer isn’t surprising. But drinking alcohol?

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Tara Walton/Toronto Star

When Michael Douglas announced in August that doctors had found a walnut-sized tumour at the base of his tongue, he explained that the cancer was caused by years of carousing: “I smoked cigarettes and I drank,” he said matter-of-factly, “and this particular type of cancer is caused by alcohol.”

That smoking leads to cancer of the oropharynx—the tonsils, soft palate, side and back walls of the throat, and base of the tongue—is well-known. But less familiar to many is the link between heavy alcohol consumption and cancer. As a recent study in the journal Head & Neck showed, 60 per cent of patients diagnosed with oral cancer identified smoking as a cause, while 20 per cent said alcohol. The medical community, however, has long known about the correlation, and now Douglas—who was treated for alcohol and substance abuse in 1992—is proving to be the de facto spokesperson for the disease.

As Dr. Jonathan Irish, a head and neck surgeon at Toronto’s Princess Margaret Hospital, points out, “Smoking is by far the most important factor for oropharyngeal cancer, but alcohol alone increases the risk of this type of cancer, and smoking and alcohol together work synergistically.” One of the leading theories about this “multiplier effect,” says Irish, is that alcohol acts as a solvent, wearing away at the soft, mucosa-lined surface of the oral cavity, and increasing the ability of material—such as carcinogens in smoke—to flow into cells. Irish says, “The risk of a person developing cancer of the head and neck from alcohol alone is two to five times the rest of population, and smoking is 10 to 20 times. But you put the two together, the person will have about 40 times the risk of developing cancer.”

Another theory is that the major metabolite of ethanol in liquor—acetaldehyde—is carcinogenic. Plus, alcohol leads to cancer in indirect ways: it suppresses immune function and can cause vitamin deficiencies. But just how much drinking is too much? “More than two units of alcohol a day is thought to be the breakpoint at which alcohol becomes potentially injurious,” explains Irish, adding that the type of alcohol is less important than the quantity imbibed. As for a profile of an oral cancer sufferer: it’s more common in men than women, and typically affects those over 40 who have had a solid relationship with drinking and smoking—like the 65-year-old Oscar-winner.

Douglas’s wife, Catherine Zeta-Jones, said she is “furious” that her husband’s cancer was not detected sooner. (He was diagnosed at stage four after months of seeking attention for ear and throat pain.) But the fact it took so long for the tumour to be discovered is also typical of oropharyngeal cancer. There is no screening test for head and neck cancers, and about 60 per cent of cases are detected at stage three or four. Dr. Jeremy Freeman, the otolaryngologist-in-chief at Toronto’s Mount Sinai Hospital, explains, “There’s a big air space down there, and by the time a tumour becomes big enough to cause interruption, it’s often at a late stage.”

While the actor undergoes an eight-week course of radiation and chemotherapy in New York, he remains hopeful. “I’m treating this as a curable disease,” he said. “It’s a fight. I’ll beat this.” For the rest of us, Irish repeats the age-old adage: “Don’t smoke—and drink in moderation. It’s just common sense.”