BBC: Cannabis cancer risk played down

[Prince_Charles]

http://news.bbc.co.uk/1/hi/health/4350642.stm



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Cannabis cancer risk played down
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<div ="cap">THC is one of 60 cannabinoids derived from the cannabis plant</div>
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Cannabis smoke is less likely to cause cancer than tobacco smoke, a leading US expert says.
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Dr Robert Melamede, of the University of Colorado, said
that, while chemically the two were similar, tobacco was more
carcinogenic.
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He said the difference was mainly due to nicotine in
tobacco, whereas cannabis may inhibit cancer because of the presence of
the chemical THC.
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But health campaigners warned against complacency.

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Cannabis remains the most commonly-used drug in the UK
with one in 10 people using it in the last year, according to the
British Crime Survey.
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Smoke
from tobacco and cannabis contains many of the same carcinogens, and
cell damage linked to lung cancer has been found in the lungs of
chronic cannabis smokers
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<div>Jean King, of Cancer Research UK</div>


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The Class C drug, which was downgraded in 2004, has already been linked to mental health problems and breathing difficulties.
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But scientists are also exploring whether it can be used
to treat a range of conditions, including multiple sclerosis and
Alzheimer's disease.
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Dr Melamede said whereas nicotine activated carcinogenic
compounds, THC - one of 60 cannabinoids derived from the cannabis plant
- had been shown to inhibit them in mice cells.
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"Compounds found in cannabis have been shown to kill
numerous cancer types including lung, breast, prostate, leukaemia,
lymphoma and skin cancer."
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But he said the effects of cannabis were complex as
evidence also suggested low doses of THC could stimulate growth of lung
cancer cells.
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Smoking
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And he added the two could interact as cannabis was often smoked with tobacco.
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"It is possible that as the cannabis-consuming
population ages, the long-term consequences of smoking cannabis may
become more similar to what is observed with tobacco.
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"However, current knowledge does not suggest that
cannabis smoke will have a carcinogenic potential comparable to that
resulting from exposure to tobacco smoke."
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Jean King, director of tobacco control at Cancer
Research UK, said many of the studies that had looked at the link
between cancer and cannabis had used purified cannabinoids. </font>



"Results from such studies may not represent the overall effects of cannabis smoke, which contains more than 400 chemicals.
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"Smoke from tobacco and cannabis contains many of the
same carcinogens, and cell damage linked to lung cancer has been found
in the lungs of chronic cannabis smokers."
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And she added there should be no complacency as cannabis
was often smoked with tobacco, which is responsible for a quarter of
all cancer deaths in the UK.

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