Scientists in the United States have developed a test which is able to predict which lung cancer tumours are most likely to recur.

The scientists say that by scanning genes they are able to identify the aggressive cancers which are most likely to return and therefore predict which patients with early-stage lung cancer will benefit from chemotherapy.

This they say means in effect that people at risk could be given the option of chemotherapy as well as surgery, and tailored-made treatment could be offered.

The researchers examined patients with early-stage non-small cell lung cancer (NSCLC), a form of the disease which accounts for about four out of every five lung cancer cases.

Currently people with the earliest stage cancer which is determined by tumour size and whether or not it has not spread beyond the lungs, are offered surgery but not chemotherapy.

However as many as 30% of such patients can expect to suffer a recurrence of the disease.

The research team from the Duke University Medical Center, looked at the genetic profile of NSCLC tumours and found there were significantly different genetic patterns between the tumours that are likely to recur and those that will not.

Dr. Anil Potti, who led the research, says the current staging system for lung cancer is very crude.

It seems that if a patient has a 2.9cm tumour, the tumour is removed, but if a patient has a 3.1cm tumour, the tumour is cut out but they would also receive chemotherapy.

By using the genome test the scientists were able to look at the tumours in 129 patients, whose disease statuses were followed over time.

They discovered the test predicted the risk of recurrence to a high degree of accuracy, about 80 percent.

Dr. Potti says even though everyone knows that 30% of early-stage patients will experience a recurrence, no-one was ever able to say which group would be the most likely to do so.

He says if this test is used with people with very early-stage cancer, those who show a higher likelihood of recurrence could be offered chemotherapy as well as surgery which could potentially save thousands of lives every year.

Dr. Potti says the test will now go into clinical trials in the U.S. and Canada in fifty medical centres with about 12,000 cancer patients in the new year.

Following surgery to remove the initial tumor, patients may or may not get chemotherapy based on their test score; they will then will be monitored for a two year period in order to gauge the outcome.

Potti hopes the results of the trial will be available in two years.

Researchers at the University of North Carolina at Chapel Hill, have also found that several new tumour profiling tests for breast cancer, including two already in general use, are equally accurate and should allow many women to avoid unnecessary treatment.

Doctors are optimistic that the growing knowledge about the genes fueling cancers will lead to better information as to who really needs chemotherapy.

They say the newly emerging tumour profiling tests are tools to help them do just that.

Some of the researchers are part owners of, or have other financial ties to, a genetic testing lab established by Duke.

Both studies are reported in the New England Journal of Medicine.