POT DOESN'T INCREASE ORAL-CANCER RISK, STUDY SAYS

Recreational marijuana smokers are no more likely to develop oral cancer than nonusers, a new study led by the Fred Hutchinson Cancer Research Center says.

The latest findings contradict a 1999 California study that implicated regular pot smoking as having markedly higher risks for head and neck cancers.

While not conclusive, the findings by "The Hutch," located in Seattle, suggest that cancers of the mouth should rank low among the known health hazards of marijuana use.

Oral cancer "probably shouldn't be one of the things people should worry about when they decide whether to smoke marijuana," said Stephen Schwartz, a member of Fred Hutchinson's public-health sciences division and the study's senior author.  "Our study found no relationship between marijuana and cancer."

Marijuana is the nation's most commonly used illicit drug.  Marijuana smoke has some of the same carcinogenic properties as tobacco, but researchers have yet to definitively establish that smoking marijuana causes any types of cancer, Schwartz said.  Tobacco is blamed for a host of cancers, including lung, kidney, cervix, bladder and pancreatic cancers.

Researchers more commonly recognize that marijuana can impair cognitive abilities, such as memory, verbal IQ and driving.  At the same time, marijuana has been shown to have some beneficial properties, including possibly boosting the body's immune system.

Schwartz said researchers were unable to find a correlation between cancer and how much and how long a person has used marijuana.  The study involved 407 oral-cancer patients and 615 healthy control subjects from Western Washington.  Most of the study participants smoked marijuana less than once a week.  Only 1 percent of the cancer patients and 2 percent of the control subjects were daily users.

Researchers from the University of Illinois, Urbana-Champaign and Seattle's Group Health Cooperative collaborated on the study.

The study refutes earlier findings by researchers at the University of California, Los Angeles, who concluded that the odds of getting head and neck cancers rose in tandem with the frequency and duration of marijuana use.

Schwartz contends the UCLA study's sample was too small and its control group - drawn from blood donors who had passed a health screening - did not accurately reflect the population at large.

Dr.  Zuo-Feng Zhang of UCLA's Jonsson Cancer Center and one of the authors of the earlier study, said he had not seen The Hutch's findings and could not comment.  But Zhang said The Hutch's study, although involving a larger sample, still is only one study and that there is no scientific consensus yet on any link between marijuana and cancer.

Zhang noted that many people who began smoking marijuana during the 1960s may just now be developing cancers of the tongue, mouth and larynx.  Zhang and his fellow researchers are conducting a larger, more comprehensive follow-up to their 1999 study.

Schwartz warned that marijuana users should not take The Hutch's findings as reassurance that marijuana is harmless, at least as far as cancer is concerned.  For one thing, marijuana's effects on "uncommonly" heavy users still are largely unknown, he said.

"I don't think we've heard the last word on this issue," Schwartz said.