Excess bodyweight raises cancers risk

Increased body mass index (BMI) increases the risk of common and less common cancers, and the level of risk can vary between the sexes and different ethnic groups depending on the type of cancer.

These are the conclusions of authors of an article – Body-mass index and incidence of cancer: a systematic review and meta-analysis of prospective observational studies – in this week’s edition of The Lancet.

Excess bodyweight, expressed as increased body-mass index (BMI), is associated with the risk of some common adult cancers. Researchers did a systematic review and meta-analysis to assess the strength of associations between BMI and different sites of cancer and to investigate differences in these associations between sex and ethnic groups.

Researchers did electronic searches on Medline and Embase (1966 to November 2007), and searched reports to identify prospective studies of incident cases of 20 cancer types. They did random-effects meta-analyses and meta-regressions of study-specific incremental estimates to determine the risk of cancer associated with a 5 kg/m2 increase in BMI.

Researchers analysed 221 datasets (141 articles), including 282 137 incident cases. In men, an increase in BMI was strongly associated with oesophageal adenocarcinoma and with thyroid, colon, and renal cancers. In women, researchers recorded strong associations between an increase in BMI and endometrial, gallbladder, oesophageal adenocarcinoma, and renal cancers. Associations were stronger in men than in women for colon cancer. Associations were generally similar in studies from North America, Europe and Australia, and the Asia?Pacific region, but researchers recorded stronger associations in Asia?Pacific populations between increased BMI and premenopausal and postmenopausal breast cancers.

Increased BMI is associated with increased risk of common and less common malignancies. For some cancer types, associations differ between sexes and populations of different ethnic origins. These epidemiological observations should inform the exploration of biological mechanisms that link obesity with cancer.

Source: Lancet, UK

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