Tall people 'more likely to develop cancer'

By James GallagherHealth reporter, BBC News

Height linked to cancers, but the reason why is unknown.

Being tall has been linked to a greater risk of 10 common cancers by University of Oxford researchers.

For every four inches (10cm) above five feet a person was, the researchers said they had a 16% increased cancer risk.

The study of more than one million women,published in The Lancet Oncology, suggested chemicals that control growth might also affect tumours.

Cancer Research UK said tall people should not be alarmed by the findings.

The study followed 1.3 million middle-aged women in the UK between 1996 and 2001.

It linked 10 cancers to height - colon, rectal, malignant melanoma, breast, endometrial (uterus), ovarian, kidney, lymphoma, non-Hodgkin lymphoma and leukaemia.

Those in the tallest group, over 5ft 9in, were 37% more likely to have developed a tumour than those in the shortest group, under 5ft.

Although the study looked only at women, the researchers said the height link was also present in men.

They combined ten other research studies which showed a similar link in men.

Reason unknown

Dr Jane Green, lead researcher and from the University of Oxford, told the BBC: "Obviously height itself cannot affect cancer, but it may be a marker for something else."

Scientists believe that as there is a link across many cancers there "may be a basic common mechanism".

They think, but have not proved, that growth hormones - such as insulin-like growth factors - may be the explanation.

Higher levels of growth factors could do two things. They could result in more cells - taller people are made of more stuff so there are more cells which could mutate and become tumours. Alternatively, they could increase the rate of cell division and turnover, increasing the risk of cancer.

But as Dr Green admitted: "The point is we don't know."

Cancer Research UK's Sara Hiom said: "Tall people need not be alarmed by these results. Most people are not a lot taller, or shorter, than average, and their height will only have a small effect on their individual cancer risk."

Dr Caitlin Palframan, policy manager at Breakthrough Breast Cancer, said: "The big question is why this connection exists. If we can unravel why height affects the risk of cancer it will lead us closer to understanding how some cancers develop."

The researchers suggested that height could also have contributed to increasing cancer incidence. In Europe, average height is thought to have increased by around 1cm every decade during the 20th Century.

They argued that the height increase in that time could have resulted in a 10-15% more cancers than if heights had remained the same.