Tall people 'more likely to develop cancer'
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 10 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."
By James Gallagher, Health reporter.
Overweight patients may have been told to lose a few inches for the good of their health in the past - this time there's nothing anyone can do about it.
Height, however, is not a universally bad thing. It is believed people are becoming taller due to better nutrition and fewer diseases in childhood.
Being tall has also been linked to reduced rates of heart disease.
It is also not the biggest contributor to cancer. A height link was greatly reduced or eliminated for some cancers in smokers - researchers said the effect of height had been "swamped".
Obesity is also a big factor, a 10 point increase in Body Mass Index increases the risk of breast cancer by around 40%.
Height might one day help doctors screen for cancer risk and it is hoped, that by furthering the understanding of cancers, the study will help researchers discover treatments.
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."
- Shortest (under 5ft) - 7.5 cancers per 1,000 women per year
- Average (5ft 3in) - 8.3 cancers per 1,000 women per year
- Tallest (over 5ft 9in) - 10 cancers per 1,000 women per year
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.