2 Body Types Linked to Increased Colorectal Cancer Risk

2 Body Types Linked to Increased Colorectal Cancer Risk

Your body type could determine your risk of developing colorectal cancer, according to new research. 

A recent study published in the journal Science Advances found that people who have obesity or are tall with fat accumulation around their midsection or waist are at an increased risk of developing colorectal cancer, regardless of their family’s history with the cancer.

Colorectal cancer is the third most common cancer worldwide and the second leading cause of death from cancer, with roughly 150,000 new cases projected for 2024, according to the American Cancer Society. Cases among people younger than 55 have been rising at an alarming rate, with diagnoses jumping from 11% in 1995 to 20% in 2019.

Other research has found that where and how your body stores fat can contribute to colorectal cancer risk. A 2022 study, for example, also found people who are obese or are tall and “centrally obese” have a higher risk of developing colorectal cancer, but the participants in that study were all of European ancestry. 

This new research is the first to find an association between higher odds of colorectal cancer and body type among people of varying ancestries: Caucasian, African, and Asian. 

Heinz Freisling, PhD, an epidemiologist at the International Agency for Research on Cancer and coauthor of the study, told Health that the results challenge the common practice of estimating cancer risk based on body mass index (BMI), a measurement often used to determine whether someone is overweight.

“Despite the usefulness of BMI at the population level, for example, to track obesity prevalence over time,” he said, “it cannot distinguish between different subtypes of unhealthy weight, for example, whether excess body weight is carried around the waist or rather at the hips.”

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For this study, researchers drew data from 329,828 people in the U.K. Biobank, a large biomedical database and research resource.

They used participants’ BMI, height, weight, waist-to-hip ratio, and waist and hip circumference to split them into four groups based on body phenotype or their observable characteristics.

The four groups were: generally obese; tall with more distributed fat mass; tall and centrally obese; and shorter with a smaller hip and waist but high weight and BMI.

Researchers found that the tall and centrally obese group had a 12% average increased risk of colorectal cancer, with the chances rising to 18% for women in that group. People in the generally obese group had a 10% higher risk of colorectal cancer.

The other groups had a small but not significant increase in their risk of colorectal cancer.

The spikes were seen across all ancestry groups, suggesting that a person’s background didn’t play a role.

“We consistently observed differences in risk for two types of body shape: more of a generally obese body shape and more of a tall and centrally obese body shape,” Freisling said. “For the time being we have mostly what we call observational evidence, whereby we compare risk for different body types in a population.”

The scientists also performed a genome-wide association study to help them identify genes associated with the various body shapes. They identified more than 3,400 genetic variants across the four body types. 

Genetic variants related to a generally obese body type showed increased gene expression in brain tissues, researchers discovered. Meanwhile, those associated with the tall and centrally obese body type had more gene expression in adipose, breast, nerve, blood vessel, and reproductive tissues. 

These differences “may reflect divergent mechanisms by which body shapes influence the risk of CRC,” the authors wrote.

Freisling said future studies could investigate the genes underlying the relationship between the four body shapes and gene expression.

The relationship between being taller and having a higher cancer risk is “remarkably robust,” according to a 2019 study. That study examined the relationship between height and cancer risk in 23 million Korean adults. Greater height was associated with increased risk for every cancer they studied except for esophageal cancer.

Another study found that the risk of eight cancers, including colorectal, increased with each additional four inches of height.

“It is believed that taller individuals might have longer colons, providing more surface area for tumor development,” Anam Khan, MD, assistant professor of Gastroenterology, Hepatology and Nutrition at the University of Texas MD Anderson Cancer Center, told Health. “This can lead to more opportunities for abnormal cell growth and genetic mutations.”

She added that other factors like hormonal imbalances, diet, and lifestyle may also play a role. For instance, taller people may eat more, which could potentially increase their exposure to carcinogens or other factors associated with colon cancer risk.

While losing weight can help prevent fat accumulation, it’s not always possible to completely change your body type. Your shape is primarily the result of genes. 

The good news is that there are other ways to decrease your risk of developing colorectal cancer. 

Those include limiting alcohol intake, exercising regularly, not smoking, and managing stress by getting adequate sleep, Hina Saeed, MD, deputy director of radiation oncology with Lynn Cancer Institute at Boca Raton Regional Hospital, told Health

Nutrition also plays a major role, Khan said. Eating more whole grains and legumes while limiting your intake of processed meats and red meat, such as beef and pork, can help decrease your risk of colorectal cancer. 

It’s also essential to get a colorectal cancer screening if eligible—the U.S. Preventive Services Task Force recommends that people at average risk start screening at age 45. 

“It’s estimated that about 55% of colorectal cases and deaths could be attributed to modifiable risk factors,” Khan said. “So it is extremely important to learn about modifiable risk factors and take proactive steps to mitigate them.”

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