Obesity-related risks for colorectal cancer not the same for men and women, says new study

Having a higher body mass index increases the risk of colorectal cancer among men more than in women and higher waist-to-hip ration heightens the risk of colorectal cancer among women rather than in men

Myupchar December 17, 2020 23:20:16 IST
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Obesity-related risks for colorectal cancer not the same for men and women, says new study

Representational image. AFP

Bowel cancer, colon cancer or rectal cancer — these names indicate a different point of origin for malignant cells, but they ultimately signify the same disease colorectal cancer. According to the World Health Organization (WHO), colorectal cancer is the third leading cause of cancer-related deaths among both men and women and there were an estimated 1.8 million cases worldwide in 2018 alone.

Colorectal cancer, therefore, poses a huge threat to the global population and those at risk of developing this type of cancer need to take every preventative step they possibly can.

Risk factors for colorectal cancer

While hereditary risk factors for any cancer cannot be changed or helped, modifiable risk factors can be regulated. The American Cancer Society explains that there are many lifestyle risk factors associated with colorectal cancer, and diet, weight and exercise are the three key ones among them.

Having a diet rich in red meats, processed meats or meats cooked at a very high temperature and even low vitamin D intake increases the risk of colorectal cancer. Additionally, people who smoke, abuse alcohol or are not physically active also have a higher chance of developing colorectal cancer.

The sum of these lifestyle factors may also have a role to play in what is perhaps the biggest risk factor for colorectal cancer — being overweight or obese.

A study published in the journal Gut in 2006 suggests that being obese — especially if associated with high abdominal or visceral fat, high waist circumference and body mass index (BMI) — has a huge impact on how your body produces and utilises certain hormones like insulin and leptin. Abnormalities in these hormones and how they interact with the cells of the colorectal region may be the main biochemical mediator between obesity and colorectal cancer.

Obesity-related colorectal cancer

While this link between obesity and colorectal cancer is largely known, the sex-specific or even site-specific links between the two isn’t that well understood. A new study published in BMC Medicine endeavours to do just that. This study, conducted by researchers at the University of Bristol, UK, was aimed at understanding two things: first, how do sex-specific associations with BMI and waist-to-hip ratio (WHR) interact with colorectal cancer risks, and second, since adiposity affects metabolism, do BMI and WHR affect metabolites differently to cause colorectal cancer.

To examine these associations between obesity and colorectal cancer, the researchers used a method known as Mendelian Randomisation (MR). They collected the data of 58,221 colorectal cancer patients and 67,694 control subjects from the Genetics and Epidemiology of Colorectal Cancer Consortium, the Colorectal Cancer Transdisciplinary Study and the Colon Cancer Family Registry. They applied sex-combined MR to find associations between BMI, WHR and 123 metabolites and then between the metabolites and colorectal cancer.

Sex-specific differences in colorectal cancer risk

Through their sex-specific MR analysis, the researchers found that a higher BMI was linked to 1.23 times higher odds of getting colorectal cancer among men, while among women this odds ratio linked to BMI was 1.09. WHR was more strongly associated with the risk of colorectal cancer among women with an odds ratio of 1.25, while in men it was found to be 1.05. They also found that 103 out of 123 metabolites were altered due to higher BMI and WHR, but they didn’t appear to have a significant positive correlation with higher colorectal cancer risks.

The researchers, therefore, concluded that having a higher BMI increases the risk of colorectal cancer among men more than in women and higher WHR heightens the risk of colorectal cancer among women rather than in men. According to the findings of this study, metabolic changes due to obesity did not have a causative link with colorectal cancer, but the researchers recommend that more detailed metabolomic measures in further research are much needed to understand this link better. They also recommend that maintaining a healthy BMI and WHR is equally important for both men and women to reduce their overall risk of colorectal cancer.

For more information, read our article on Colorectal cancer.

Health articles in Firstpost are written by myUpchar.com, India’s first and biggest resource for verified medical information. At myUpchar, researchers and journalists work with doctors to bring you information on all things health.

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