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Adiposity is associated with an increased risk of ten cancer sites

Mon, 05/10/2021 - 09:38
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Adiposity is associated with an increased risk of ten cancer sites and the associations were mostly linear among all adiposity markers, according to researchers from the University of Glasgow. They also noted that there was no evidence that the use of other adiposity markers, such as central adiposity or body fat, improves the prediction ability for cancer risk beyond the risk attributable to BMI. The findings from the paper, ‘Associations of six adiposity-related markers with incidence and mortality from 24 cancers - findings from the UK Biobank prospective cohort study’, were published in BMC Medicine.

The study, which included more than 400,000 adults in the UK, was presented at The European Congress on Obesity (ECO), with larger waist and hips and general obesity (body mass index [BMI] and body fat percentage) associated with similar estimates of cancer risk. The results, the authors suggest, indicate that BMI is an adequate measure of cancer risk from excess weight, and there is no advantage in using more complicated or expensive measures such as waist circumference or body fat percentage.

Using data from the UK Biobank prospective cohort study, the researchers from the University of Glasgow identified 437,393 adults (54% women; average age 56 years) who were cancer-free, to investigate the risk of developing and dying from 24 cancers according to six markers of obesity:

  • BMI
  • body fat percentage
  • waist-to-hip ratio
  • waist-to-height ratio and;
  • waist and hip circumferences

The results were adjusted for age, sex, ethnicity, deprivation, education, smoking, alcohol consumption, intakes of fruit and vegetables, red and processed meat, oily fish, physical activity, and sedentary behaviours. After an average of nine years follow-up, there were 47,882 cases of cancer, and 11,265 cancer deaths.

The researchers found that all six obesity measures were positively and similarly associated with higher risk for ten cancers. For example, each 4.2 kg/m2 (men) and 5.1 kg/m2 (women) increase in BMI above 25 kg/m2 (defined as being overweight) was linked with higher risk of cancers of the stomach (35% increase), gallbladder (33%), liver (27%), kidney (26%), pancreas (12%), bladder (9%), colorectal (10%), endometrial (73%), uterine (68%), postmenopausal breast (8%), and overall (3%) cancer.

Based on the results, the researchers estimate that if these associations were causal, having overweight or obese could be responsible for around 40% of endometrial and uterine cancers and 29% of gallbladder cancers; and could account for 64%, 46%, and 40% of deaths from these cancers, respectively.

"We observed a linear association, the more severe obesity is, the higher the risk of developing and dying from these cancers, except for postmenopausal breast cancer", said Dr Carlos Celis-Morales from the University of Glasgow, UK, who led the research. "But there was a lot of variation in the effects of obesity on different cancers. This tells us that obesity must affect cancer risk through a different number of processes, depending on the cancer type."

The researchers say they cannot rule out the possibility that other unmeasured factors (residual confounding) may have influenced the results. They also note that the study is not a representative sample of the UK adult population, so the results might not be generalisable to the general population.

To access this paper, please click here