TOBACCO IS 'LESS RISKY THAN DOPE'

US Research Says Cancer More Than Twice As Likely For Cannabis Smokers

For decades, it has been been the retort of cannabis smokers: dope is not
as bad for you as cigarettes or alcohol. But after years of ambiguous
research, US scientists claim it is worse.

Regular smokers of cannabis can be more than 30 times as likely to get
cancer of the neck, throat, mouth and larynx as those who have never
inhaled. Nor does giving up the weed cut the risk. According to the
research, quitting does not reduce the damage.

Previous research has shown dope and cigarette smokers can develop
pre-cancerous changes in throat-lining cells. But this study, carried out
in New York, is the first definitely to link the smoking of joints to full
cancers of the head and neck.

It suggests that the drug's popularity in recent decades could lead to
swaths of the population with cancer. Teenagers in the Sixties - first to
enjoy regular use of cannabis - are now reaching the age when such types of
cancer are likely to occur.

Marijuana smoke is higher in tar and carcinogens than tobacco smoke.
Researchers at New York's Memorial Sloan-Kettering Cancer Centre decided to
investigate the health risks of marijuana because people who use the drug
tend to inhale deeply and keep smoke in their lungs as long as they can,
depositing four times more matter in mouth, throat and windpipe than
cigarettes.

They enrolled 173 patients with head or neck cancer, and a group of 176
cancer-free blood donors of similar age. Participants were quizzed about
past use of marijuana, tobacco and alcohol, plus workplace and
environmental exposure to possible carcinogens. Frequency of marijuana use
was categorised as never, less than or equal to once a day, and more than
once a day. Duration of use was categorised as never, one to five years and
more than five years.

Among those who had used marijuana, the risk of head and neck cancer was
2.6 times greater than among those who never used it, even after adjusting
for other risk factors such as alcohol and tobacco smoking.

Researchers found that the more dope smoked, the more likely cancer would
develop. Among people who reported smoking marijuana once a day, the risk
of head and neck cancer was 2.1 times that of those who never used it.
Among those who smoked it more than once a day, the risk was 4.9 times
greater.

But risk of head and neck cancer was far higher if people also smoked
cigarettes, incidating that the two work together to promote cancer
development. Users of both substances had 36 times the risk of head and
neck cancer found in people who used neither.

The study did not look at dope-smoking and lung cancer, but the effects are
thought to be similar. Researchers in the field welcomed the study, saying
it proved what they long suspected. 'It appears marijuana smoke is a
stronger carcinogen than cigarette smoke. It's what I expected to see,'
said Li Mao, professor of medicine at M.D. Anderson Cancer Centre in
Houston, Texas.

The report has far-reaching implications for the British Government, which
last month announced the first official research into medical use of
cannabis, and its effects of relieving pain in a wide range of conditions,
including multiple sclerosis. Scientists will have to learn to deliver any
cannabis benefits without high cancer risk.

There is some comfort for dope smokers who presumed it relatively harmless.
One joint is more dangerous than one cigarette, but the effect of
cigarettes on health is probably greater, said Eugenia Calle of the
American Cancer Society, 'because people just smoke so many more
cigarettes'. Even heavy dope smoker would be unlikely to get through 20
joints a day every day for 50 years.