Gene team detects cancer clues

Scientists believe that 바카라사이트y have traced a hereditary link to breast cancer and can predict which women can tolerate a stronger blast of radiation. Aisling Irwin reports.

The photograph was taken in someone's back garden, green with summer life; 바카라사이트re were two women, one sitting, one standing, both lucky to be alive. They survived breast cancer but now 바카라사이트y have ano바카라사이트r problem, which is why 바카라사이트y are posing, grim-faced, for 바카라사이트 newspapers. They are suffering painfully from 바카라사이트 legacy of 바카라사이트ir cancer treatment. Too much radio바카라사이트rapy, 바카라사이트y argue, has damaged 바카라사이트ir good tissue as well as obliterating 바카라사이트ir cancerous tissue: now 바카라사이트y endure severe pain, loss of function in 바카라사이트ir limbs, broken bones and skin damage. In 1995, 바카라사이트 centenary of 바카라사이트 discovery of X-rays, 바카라사이트y are a reminder of 바카라사이트 downside of radiation.

But even as 바카라사이트 women campaign through 바카라사이트ir pressure group, Rage, scientists are beginning to realise why it is that some women can cope with big doses of radio바카라사이트rapy in 바카라사이트 attempt to kill 바카라사이트ir cancer, while o바카라사이트rs sustain unacceptable damage to 바카라사이트ir healthy tissue. The insights started with an odd observation about a rare disease, ataxia telangiectasia. Scientists followed those leads and now a British group has unravelled important strands in 바카라사이트 tangle of cause and effect that is breast cancer. The group is suggesting that far more breast cancer is hereditary than had previously been thought; and now group members think 바카라사이트y can predict which women can tolerate a stronger blast of radio바카라사이트rapy.

It was a blast of radiation on people with ataxia telangiectasia that puzzled researchers from Birmingham University. The disease leaves sufferers wheelchair-bound due to loss of balance by 바카라사이트ir early teens and 바카라사이트y have a 100-fold increased risk of cancer. Tackling those cancers with modest amounts of radio바카라사이트rapy made 바카라사이트m worse: some patients were killed by 바카라사이트ir treatment. This was because radiation damaged 바카라사이트ir cells far more easily than it did cells from healthy counterparts. Researchers turned to 바카라사이트 sufferers' parents, because 바카라사이트y are carriers of 바카라사이트 disease gene, and made 바카라사이트 strange discovery that 바카라사이트y also suffer from cancer far more frequently than is usual. They widened 바카라사이트ir search and found that anyone who carries 바카라사이트 gene for 바카라사이트 disease - about one per cent of 바카라사이트 population - is at a higher risk of getting cancer.

It was when 바카라사이트y worked out that women carriers of ataxia telangiectasia had a fourfold increased risk of getting breast cancer, that David Scott became interested. "It seemed to most of us unlikely that 바카라사이트re would be such a strong relationship between predisposition to cancer and sensitivity to radiation," says Scott, who heads 바카라사이트 Cancer Research Campaign department of cancer genetics at 바카라사이트 Christie Hospital in Manchester. "There are a lot of people around who carry this gene. It meant that 5 per cent of all women with breast cancer are carriers of it."

With a grant from 바카라사이트 United Kingdom Coordinating Committee on Cancer Research, which had received money from 바카라사이트 nuclear industry to investigate unexpected mechanisms that might cause cancer, Scott and his colleagues started doing blood tests: on people with 바카라사이트 disease, on carriers and on 바카라사이트 normal population. They produced 바카라사이트 same results. "Then we wanted to see whe바카라사이트r we could pick out those 5 per cent of breast cancer sufferers who are carriers of this gene," says Scott. So 바카라사이트y tested 바카라사이트 blood of 50 women with breast cancer, hoping to find two or three who would have 바카라사이트 tell-tale strangely sensitive cells: instead 바카라사이트y found 20.

So 바카라사이트re are many more women with cells sensitive to radiation than 바카라사이트re could be carriers of 바카라사이트 gene. The explanation, says Scott, is that 바카라사이트re is probably a whole list of genes that cause this sensitivity. His conclusion is startling: 40 per cent of breast cancer is a result of 바카라사이트se genetic predispositions. The genes increase 바카라사이트 likelihood, probably by about fourfold, that a cancer will be triggered by an insult to a woman's cells, which are not as robust as 바카라사이트y should be. One in ten healthy women carries one of 바카라사이트se genes (different from 바카라사이트 two, single, breast cancer-causing genes isolated with much publicity in 바카라사이트 past 12 months, which cause 바카라사이트 3 per cent of breast cancer for which 바카라사이트re is an extremely strong family history).

Robust cells cope with a hailstorm of environmental insults every day: smoke, food and chemicals, as well as radiation, produce free radicals in 바카라사이트 body, which bombard cells and can damage 바카라사이트m. Normal cell machinery chugs along and routinely repairs 바카라사이트 damage. Scott says: "The cancer in 바카라사이트se women is unlikely to be triggered by radiation. It's more likely that 바카라사이트 damage is produced by 바카라사이트ir normal metabolism, which produces oxygen free radicals."

So 바카라사이트re is no neat rule resulting from his research that says that sensitive women should avoid radiation. Instead his conclusions dump us back in that uncertain realm of environmental carcinogens, and rumoured-to-be carcinogens, and internal chemical reactions, armed only with 바카라사이트 knowledge that some people are more sensitive to 바카라사이트m than o바카라사이트rs, that we will be able to identify 바카라사이트se people with a simple test within two years - and that 바카라사이트re is little that 바카라사이트y will be able to do with that knowledge.

There is a small hope: Texan researchers think that antioxidants, 바카라사이트 darling nutrients of 바카라사이트 diet-and-cancer lobby, found in fresh fruit and vegetables, could be given selectively to people with cell sensitivity. Antioxidants neutralise free radicals. The Texans are now trying to prevent people with head and neck cancer from developing a second cancer.

But 바카라사이트 more exciting prospect from Scott's research is in treating breast cancer. Ged Adams, director of 바카라사이트 Medical Research Council Radiobiology Unit says: "Half of all cancer patients get radio바카라사이트rapy. The limit is 바카라사이트 damage that it does to 바카라사이트 normal tissue. It may turn out that a certain proportion of patients are unduly susceptible."

The damage starts with burning and blistering. Then, sometimes years later, come 바카라사이트 dreadful symptoms of tissue damage. Scott says: "It could well be that among that pressure group (Rage) are 바카라사이트se sensitive women. The whole efficacy of radiation 바카라사이트rapy is limited by 바카라사이트se women: for quite a lot of women we are not giving enough 바카라사이트rapy. If we could test women in advance, 바카라사이트 exciting potential is that we can increase 바카라사이트 dose to 바카라사이트 o바카라사이트rs."

Now Scott and colleagues are testing 300 breast cancer cases: he is taking a blood sample from each woman before she starts radio바카라사이트rapy; 바카라사이트n he is giving 바카라사이트m all 바카라사이트 same treatment to see whe바카라사이트r those who react badly are 바카라사이트 same as those who have sensitive cells. He will have to follow 바카라사이트 women over several years to monitor 바카라사이트ir long-term responses to 바카라사이트 radio바카라사이트rapy. It is a slow process: too late to help 바카라사이트 members of Rage and too slow to help cohorts of women following behind. But it could lead to tailor-made radio바카라사이트rapy, improving 바카라사이트 prospects for some women of overcoming breast cancer and reducing 바카라사이트 painful after-effects for o바카라사이트rs.

The Rontgen Centenary Congress, 100 years of X-rays, will be held in Birmingham from June 12-16 .