It was music to the ears of smokers everywhere - scientists had discovered a single gene that seemed to protect against cigarette-related cancers. Even better was the reported promise that within a few years there might be a tablet that could bump-up resistance to cancers from smoke. If you were one of those susceptible to illness then a trip to the local pharmacy would sort you out.

The Scottish-based Imperial Cancer Research Fund (ICRF) team at the centre of the media blitz that followed the announcement was appalled. Researchers involved in the highly significant study found themselves "talking down" the work as it became apparent that it would be reported as a protection against cancers from smoking, explained Dr Colin Henderson, an ICRF scientist working at Ninewells Hospital and Medical School, Dundee, and the report's principal author.

The work was almost portrayed as "a smokers' charter" he said, but the group's findings were anything but that. "I can't emphasis this enough," he said yesterday. "You must not smoke. I am fiercely anti-smoking."

Henderson's study included group leader, Prof Roland Wolf and Dr E. Jane Bacon both of Ninewells, Dr Austin Smith and Dr Jan Ure of the University of Edinburgh and Dr Ken Brown of the Cancer Research Campaign Beatson Laboratories in Glasgow.

Their work focused on a mouse enzyme, a chemical, which was known to be very effective at breaking down toxic substances. They developed a mouse that could not produce this specific enzyme, known as GstP, and then treated its skin with toxins common in cigarette smoke. The researchers found that mice without GstP developed up to 10 times more cancers than mice with GstP.

The finding was highly significant, stated Dr Henderson. There had been indirect evidence for years that the Gst enzyme family was somehow involved in cancers but "no direct evidence".

The work in Scotland, first published in the US-based Proceedings of the National Academy of Science, provided conclusive evidence that at least one of the enzyme family, GstP, was closely involved. "We were pleasantly surprised when we found it had such an effect," Dr Henderson said.

When the study was subsequently interpreted by the media however, several intuitive leaps were made. The chemicals, polycyclic aromatic hydrocarbons, were common in cigarette smoke, although they were chosen not for this reason but because they are well established, known carcinogens. They were applied to and caused mostly benign cancers on mouse skin, not lung tissues. Finally, the tests were on mouse models and not based on studies of human illness.

The smoking angle allowed an immediate jump to the human condition. This linkage was strengthened because Gst enzymes are also found in humans and GstP is one of the most common in human lung and bladder tissues, the tissues most susceptible to smoking related cancers.

The researchers' excitement - and the significant of their work - relates to the parallels in the way Gst enzymes work in humans and mice. They conclude, in their PNAS report that: "The finding that GstP can profoundly alter susceptibility to carcinogenesis in the mouse indicate that individual variability in the expression of this gene also may be an important factor in cancer susceptibility in humans."

This should be interpreted as a researchers' call to arms, a statement that in the vernacular equates to: "Hey lads, look what we found in mice. Maybe the same thing happens in humans. Why don't you have a look."

The study doesn't mean we should expect to take a pill to ward off smoking-related cancers, at least in the short-to medium-term, Dr Henderson suggested. Yet it is an exciting finding precisely because it points the way towards more GstP related research in humans.

"It may start to explain and be one of the many factors that explain why some get cancer and others don't," he said. GstP is the leading Gst in human lung tissue. How can this information be used? Another Gst, Gstmu, is found in only half of the general population and some studies indicate that those without Gstmu might be more susceptible to smoking cancers. Can this be used to develop a drug substitute for Gstmu? Who knows?

What is known, with no shadow of doubt, is that smoking increases incidence of disease and death in those exposed to it. Ash Ireland is unequivocal. There are 6,000 smoking-related deaths in Ireland each year including cancers, vascular disease and heart disease. Of this 6,000 there are 1,500 lung cancer deaths. The clear message, according to Dr Henderson, is that if you want to live longer, don't smoke, despite the promise of what might be discovered in the laboratory.