Patients with non-operable head and neck cancers should be given chemo- and radiotherapy at the same time, as it more than doubles the time they live without the disease getting worse, British scientists said on Wednesday.

Researchers from the UK Head and Neck (UKHAN) cancer group said their study offered doctors a cheap and simple way of treating a high risk category of patients, many of whom continue to drink and smoke even during treatment.

About 400,000 cases of head and neck cancer are diagnosed globally each year, including some 45,000 in the United States and 7,500 in Britain.

Heavy smokers and drinkers are at highest risk of developing head and neck cancers, which can be difficult to operate on. More than half of patients die from the disease.

The current standard treatment for head and neck cancers is radiotherapy with or without surgery, but recent research has suggested that adding chemotherapy can increase survival.

The UKHAN researchers' study, published in The Lancet, compared the effect of different combinations of treatments in 966 patients with advanced head and neck cancer.

After 10 years, they found that giving chemotherapy and radiotherapy at the same time had reduced deaths and the number of recurrences of cancer in patients who had not had surgery.

It more than doubled the time patients lived without getting worse to over two years, compared with one year on radiotherapy alone.

But for those who had undergone surgery, the double treatment had no added benefit.

Jeffrey Tobias of oncology department of University College Hospital in London, who led the study, said that finding a relatively simple, inexpensive way of treating head and neck cancer patients was essential because this is a high risk and generally unfit patient group, many of whom are excessive users of alcohol and tobacco throughout treatment.

The combined chemo-radiation therapy would considerably improve the likelihood of completing treatment, he added, and also increase the chance of beating a patient's cancer.