OVERWEIGHT people are even more likely to suffer from cancer than previously thought, according to Manchester researchers.

Common forms of the disease, including breast, bowel and kidney cancers, are increasingly being linked to obesity.

But a new study reveals rarer blood and skin cancers are also more likely to affect fat people.

Dr Andrew Renehan, from Manchester's specialist Christie Hospital, looked at 221 previous studies to investigate the impact of a significant weight gain for 20 types of cancer. He found a 15kg (2st 5lb) weight rise in women triggered up to a 50 per cent increase in the risk of cancer in the oesophagus and a 30 per cent increase in thyroid cancer risk.

A 13kg (2st) weight gain in women would increase the risk of gall bladder and womb cancers by more than half.

Researchers also saw smaller but significant links between increases in weight and kidney, bowel and skin cancers in men, kidney, pancreatic, thyroid, colon and some breast cancers in women and blood cancers including leukaemia and non-Hodgkin's lymphoma in both.

Dr Renehan said: "This was a hugely comprehensive piece of research. For some cancer types, associations differ between sexes and ethnic groups.

"This study shows a lot of people - everyone who would be considered overweight on the Body Mass Index Chart - are at increased risk of cancer, and the risk increases for every few stones they put on.

"Over the past five years, there has been increasing proof that obesity is linked with cancer risk, but despite this, we do not know whether weight reduction in people protects them against cancer. The message is: Don't become overweight in the first place."

The study, published in the medical journal The Lancet, looked at data from 250,000 cancer patients from all over the world. Dr Renehan worked with two other researchers from Manchester University and staff from the University of Bern in Switzerland.