Genetics: These are testing times

Genetic tests can now help assess our risk of developing certain cancers. Soon, they may be available to use at home. But what, asks Clare Rudebeck, are we do with the knowledge?

Freda Regan has cancer in her genes. Over five generations in her father's family, 17 people have died of a rare form of oesophageal cancer. As a result, she started having regular screenings for the disease in the early 1980s. In 1986, cancer was found, and she underwent an operation which removed part of her oesophagus. Sixteen years on, she is still healthy; last week she celebrated her 67th birthday.

Her daughter, Janet, 32, also believes her genetic make-up makes her more susceptible to the cancer. And she has found the knowledge increasingly difficult to live with. "There is very little that doctors can do for us," she says. Although she has regular screenings, she can't face the surgery that saved her mother. "It's too strenuous. I wouldn't do it," she says. "I saw my auntie die over the 12 months after she had the same operation." The procedure involves moving the stomach into the chest. Freda is the longest surviving person to have had the operation.

Genetic tests for a host of diseases are expected to be available within the next few decades. Like Janet, we all soon may be faced with the awful knowledge of what diseases we are likely to develop in later life. Tests that can help to assess the risk of breast cancer and bowel cancer are already available. Paul Nurse, joint head of Cancer Research UK, believes that over the next 50 years, genetic testing for cancer will become so advanced that life insurance and the private medical system will become defunct. Meanwhile, on the internet, you can now buy genetic tests which predict your susceptibility to diseases such as obesity and osteoporosis.

But is our future health really written so indelibly in our genes? An increasing number of women who have a history of breast cancer in their families believe it is. Ten years ago, a handful of people were referred to Cancer Research UK's six family cancer clinics wanting to know if they were at a greater risk of developing the disease. Now, each clinic receives about 500 referrals annually. If the cancer genes BRCA1 and BRCA2 are found, some of these women then opt to have both breasts removed rather than endure years of screenings and the accompanying anxiety.

But consultant geneticist Anneke Lucassen says that we should not place so much blind faith in our genetic make-up. "On their own, our genes cannot tell us our future," says the senior lecturer at Princess Anne Hospital, Southampton. "We are also creatures of our environment. The two factors together shape our health." She points out that only five to ten per cent of breast cancers can be traced to BRCA1 and BRCA2. The others are a result of unknown environmental and genetic factors. Not only this, but the genetic test itself is fallible. "Not everyone with the cancer gene will get the disease," she says. "It just increases the probability to, at most, 80 per cent."

Some tests are more reliable than others. Conditions such as Huntington's disease and cystic fibrosis, for example, are caused by a mutation in a single gene. A genetic test can show without doubt whether a person will develop either disease in later life. But for conditions such as many cancers, tests can only show an increased risk.

As a result, Dr Lucassen fears that the growing number of genetic tests may raise anxiety without saving lives. "For many conditions, a genetic test would only be able to tell you that your risk of developing a disease is, say, ten per cent instead of an average of five per cent. What would you do with that knowledge?" she asks. And, even if the test is more reliable, there is often little a person can do to reduce their risk of developing a disease.

Janet Regan now knows she is likely to contract oesophageal cancer but, because current treatments are ineffective, all she can do is have regular screenings. Only six per cent of men and seven per cent of women survive for more than five years after diagnosis with the disease.

The results of genetic tests also make it harder to get life insurance. Janet can not afford life insurance at the rate which was offered to her after her insurers discovered her family's history of cancer. Dr Lucassen confirms that some people decide not to have a genetic test, fearing it may affect their insurance premiums, although the insurance industry has now imposed a five-year moratorium on the use of genetic test results. There are also fears that a positive test for a cancer gene could damage an individual's employment prospects.

Yet, genetic tests for some conditions are now freely available over the internet. The American company, GeneLink, for example, sells tests for obesity and osteoporosis on their website. Until last month, a British company, Sciona, was selling genetic tests direct to the public. Their genetic screen claims to identify common mutations in nine genes which affect nutrition and metabolism. The firm then gives dietary advice based on each customer's genetic profile. Sciona's chief executive, Chris Martin, confirmed that the firm would launch a new test relating to heart disease at the end of the month. Within four years, Sciona hopes to market tests which can predict a person's susceptibility to some cancers.

"It's far better to avoid disease before it happens rather than have to treat it," says Dr Martin. "I think most people would welcome that chance." However, Sciona has come under fire for selling its products direct to the public. A consumer campaign highlighted a lack of scientific evidence of a relationship between genes, diet and health and criticised the company for not telling its customers about the insurance and employment consequences of taking the tests. "Scientists cannot yet tell you what to eat based on your genetic make-up," said Helen Wallace, deputy director of GeneWatch UK, who has been leading the campaign. "A healthy diet is important whatever genes you have," Dr Wallace explains. Sciona now only sells its products through health professionals.

However, there is nothing illegal about selling genetic tests over the counter. Last month, the Human Genetics Commission launched an urgent consultation into genetic tests sold direct to the public. Baroness Helena Kennedy, chair of the Human Genetics Commission, said she was concerned that these tests were available "without the option of discussing the results and their possible implications with a doctor". There are currently no specific legal requirements in Britain about who can supply genetic tests or about how results are given to customers.