A high BMI is correlated with increased risk of developing papillary thyroid cancer (PTC) in both men and women, reveals a new study published in Thyroid.

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According to current predictions, by 2020 PTC will constitute the third most prevalent malignancy among US women. Erich Sturgis, senior author of the study, finds the rise in PTC incidence alarming. “Whilst this increasing incidence is likely to be mostly attributable to over-diagnosis of subclinical PTC because of increased sensitivity, use and availability of diagnostic imaging studies, we and others feel that there is also an appreciable true increase in PTC incidence.” Prior to the study, the authors noted that the regions in the USA in which the PTC epidemic was most pronounced were the same areas in which the incidence of obesity had been increasing.

Sturgis and colleagues pooled data from three case–control studies in Italy, Germany and the USA, including a total of 1,917 PTC cases and 2,127 controls without cancer. They used multivariate analyses to evaluate associations between anthropometric measurements (including BMI, body fat percentage, body surface area and height) and PTC incidence. Age, sex, race and study site were also considered in the study.

A high BMI and a high body fat percentage were the two factors most significantly associated with PTC risk in the pooled analysis, as well as when groups were examined according to age, sex and study site. The risk of PTC was 1.7-fold increased among overweight individuals and 4.2-fold increased among those with obesity compared with that in people with a normal weight. The risk of developing PTC among participants in the highest quartile of body fat percentage was 3.8-fold and 4.1-fold increased in men and women, respectively, compared with the risk among those in the lowest quartile.

These results confirm previous studies linking thyroid cancer and obesity in women and, according to Sturgis, extend the same association to men.