CANNABIS SMOKING LINKED TO CANCERS OF HEAD, NECK

DRUG pushers might soon have to issue health warnings when selling
cannabis -- Ireland's most popular illegal drug -- following the
discovery in the US that smoking marijuana can cause cancer.

In a medical first, researchers at UCLA's Jonsson Cancer Centre are
reporting that smoking cannabis increases the risk of head and neck
cancers.

Some ageing hippies might now decide its the time to come off the
grass following the results of an epidemiological study published in
the peer reviewed journal Cancer Epidemiology Biomarker and Prevention.

Up to this, laboratory and clinical studies have indicated that
marijuana use may be related to molecular alterations in the
respiratory tract, changes that may lead to cancer. This is the
first study to examine whether smoking marijuana increases risk of
head and neck cancers, said Dr Zuo Feng Zhang of UCLA's Jonsson
Cancer Centre, a professor in the Department of Epidemiology in the
UCLA School of Public Health.

Most people don't think about marijuana in relationship to
cancer, said Dr Zhang.

The carcinogens in marijuana are much stronger than those in
tobacco. The big message here is that marijuana, like tobacco, can
cause cancer, said Dr Zhang.

He studied the relationship between marijuana use and head and neck
cancers in 173 patients diagnosed with those diseases. He compared
those findings to 176 cancer free control patients, and found that
those who habitually smoked marijuana were at higher risk for head and
neck cancers. The epidemiological data was collected by questioning
patients about their histories of tobacco smoking, cannabis smoking
and alcohol use. Dr Zhang said researchers were able to evaluate the
data on marijuana smoking independently from data on tobacco smoking
and alcohol use, which also increase the risk of certain cancers.

The findings will come as a shock to those smoking cannabis since the
1960s because head and neck cancers -- cancers of the mouth, tongue,
larynx and pharynx -- take a long time to develop.

People who smoked large amounts of marijuana in the 1960s may just
now be contracting head and neck cancers, Dr Zhang said, adding
that cannabis smokers are 16 times more likely to develop these
cancers than people who never smoked Ireland's most popular illegal
drug.