21 july 2011

Height clue to cancer risk


MoMa height exhibit
Being tall has been linked to health risks: people mark their height at a MoMa exhibit. Photo: Roman Ondak

Taller people are at increased risk of a wide range of cancers, according to new research led by Oxford University.

The study found that in women the risk of cancer rises by about 16% for every 10cm (4 inches) increase in height. Previous studies have shown a link between height and cancer risk, but this research extends the findings to more cancers and for women with differing lifestyles and economic backgrounds.

A report of the research is published Online First in The Lancet Oncology.

‘We showed that the link between greater height and increased total cancer risk is similar across many different populations from Asia, Australasia, Europe, and North America,’ said Dr Jane Green, lead author of the study, who is based at the Cancer Epidemiology Unit at Oxford University.

‘The link between height and cancer risk seems to be common to many different types of cancer and in different people; suggesting that there may be a basic common mechanism, perhaps acting early in peoples' lives, when they are growing.’

To investigate the impact of height on overall and site-specific cancer risk, Dr Green and colleagues assessed the association between height, other factors relevant for cancer, and cancer incidence, in the Cancer Research UK-funded Million Women Study, which included 1.3 million middle-aged women in the UK enrolled between 1996 and 2001. During an average follow-up time of about 10 years, 97,000 cases of cancer were identified.

The risk of total cancer increased with increasing height, as did the risk of many different types of cancer, including cancers of the breast, ovary, womb, bowel, leukaemia and malignant melanoma. The authors also conducted a meta-analysis combining their results with those from ten previous studies.

Although it is still not clear how height increases cancer risk, it has been suggested that environmental influences including diet and infections in childhood, as well as growth hormone levels, might be involved. The results suggest that increases in the height of populations over the course of the 20th century might explain some of the changes in cancer incidence over time.

Dr Green said: ‘Of course people cannot change their height. Being taller has been linked to a lower risk of other conditions, such as heart disease. The importance of our findings is that they may help us to understand how cancers develop.’