So cannabis is highly effective in cancer treatment (Letters, June 1)? I am truly lost for words.

There was I thinking cannabis is a major cause of cancer, because of its high tar content.

Of course, if you're familiar with the work of Dr Zuo-Feng Zhang of the Jonsson Cancer Center at the University of California, Los Angeles, you would be in no doubt that marijuana can trigger cancer.

Writing in the journal Cancer Epidemiology Biomarker and Prevention, Dr. Zhang said he ran tests on 173 patients suffering from head and neck cancer, and compared them with 176 cancer-free control patients.

He found that those patients who habitually smoked cannabis were more likely to be in the group with head and neck cancers.

"If you smoke a little, your risk increases a little," said Dr. Zhang. "If you smoke a lot, your risk increases a lot."

These findings are dramatically at odds with the image of cannabis being promoted by the Legalise Cannabis Alliance et al.

The big message here is that marijuana, like tobacco, can cause cancer.

The carcinogens in cannabis are actually much stronger than those in tobacco.

I leave it to impartial specialists such as Dr. Zhang to advise us about the properties of cannabis, not politicos with an axe to grind such as Steve Clements, a self-confessed user.

Aled Jones,

Mount Crescent,

Bridlington.

Updated: 09:21 Friday, June 03, 2005