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Obesity and risk of pancreatic cancer

 

Clinical bottom line

Obesity is a risk factor for pancreatic cancer, but the risk is small.


Background

Here is another case of individual papers finding inconsistent results and a meta-analysis aiming to provide a definitive answer. This time the association is between obesity and risk of pancreatic cancer.

Reference


A Berrington de Gonzalez et al. A meta-analysis of obesity and the risk of pancreatic cancer. British Journal of Cancer 2003 89: 519-523.


Systematic review

Studies were identified through searches of MEDLINE (1966-2003), Embase (1980-2003), the Science Citation Index (1981-2003), the bibliographies of selected papers and review articles. Studies were required to have reported relative risks according to categories of body mass index or per unit increase in body mass index.

The relative risk per unit increase in body mass index was estimated for each of the studies. A unit increase in body mass index for a male of 1.78 m represents weight gain of approximately 3 kg. For a female of 1.64 m a unit increase in body mass index represents weight gain of approximately 2.5 kg.

Results

Six case-control and eight cohort studies with 6,391 cases of pancreatic cancer were identified.

The summary relative risk per unit increase in body mass index was 1.02 (95% CI 1.01 to 1.03).

This per unit increase is equivalent to a relative risk of 1.19 (95% CI 1.10 to 1.29) for obese individuals (body mass index >30 kg/sq m) compared to those with a normal body weight (body mass index 22 kg/sq m).

Comment

Further analysis found summary relative risks to be similar for males (1.03) and females (1.02); in cohort and case-control studies (1.03 and 1.02); in the nine studies that had adjusted for smoking (1.03) and five studies that had adjusted for diabetes (1.03).