Overweight Adults at Higher Risk of Colorectal Cancer, Study Finds

Overweight Adults at Higher Risk of Colorectal Cancer, Study Finds
This combination of file photos made in 2016 shows (from L) obese people in Los Angeles, Mexico City, and Manchester. (Robyn Beck, Ronaldo Schemidt, Paul Ellis/AFP via Getty Images)
Naveen Athrappully
5/22/2023
Updated:
5/22/2023

Being overweight or obese can raise the risk of colorectal cancer, new research has found.

Colorectal cancer forms in the colon or rectum.

The study, published in the JAMA Network on May 10, analyzed 135,161 individuals aged 55–74 to assess the link between body mass index (BMI) and the risks of gastrointestinal (GI) cancers like colorectal cancer (CRC).

During the follow-up, 34,946 individuals were diagnosed with cancer, accounting for 25.9 percent of the total participants. Out of this, 5,088 were GI cancers, with 2,803 colorectal cancers.

“Overweight BMI in early adulthood and overweight BMI in middle adulthood and later adulthood as well as obese BMI in middle adulthood and later adulthood were associated with increased risk of CRC,” the study said.

“Maintaining overweight or obese BMI or increasing BMI to overweight or obese in later adulthood was also associated with increased CRC risk.”

The World Cancer Research Fund and the International Agency for Cancer Research have estimated that roughly 20 percent of cancers may be attributed to excess weight gain, the study said.

Researchers pointed to “chronic inflammation” triggered by obesity for the gastrointestinal cancer risks among individuals with excess weight.

“Chronic inflammation has been shown to be associated with increased risk of several GI cancers, such as pancreatic (pancreatitis), esophageal (esophagitis and Barrett esophagus), and colorectal (ulcerative colitis and Crohn disease).”

Excess fat in the body can create an environment of low oxygen, raising the risk of cancer and possibly CRC.

Insulin is another potential factor. Obese individuals are at risk of developing insulin resistance. In such a situation, the body becomes more resistant to processing glucose owing to which more insulin is created. High levels of insulin can promote the growth of colon cancer.

A June 2022 study published by the National Library of Medicine estimated that around 11 percent of CRC in Europe can be attributed to being overweight.

Among men, obesity could be associated with a 30 to 70 percent increased risk of colon cancer, it said.

“Visceral fat or abdominal obesity seems to be of greater concern than subcutaneous fat obesity, and any 1 kg/m2 increase in body mass index confers more risk,” the study said.

Risks and Symptoms

Colorectal cancer is the third most prevalent type of cancer in the United States. The National Cancer Institute estimates that people with obesity are 1.3 times more likely to have colorectal cancer.

The American Cancer Society estimates that 106,970 new cases of colon cancer and 46,050 new cases of rectal cancer will be reported this year.

Though the risk of CRC falls with age, cases of colorectal cancers have been rising among adults below the age of 50 in the United States and other nations like Canada and Australia.

In 2021, the U.S. Preventive Services Task Force issued updated guidelines recommending that individuals who are at average risk of CRC begin screening for it from 45 years of age, down from the earlier recommendation of 50 years.

In addition to being overweight or obese, other risk factors for colorectal cancer include little to no physical activity, moderate to heavy alcohol consumption, eating lots of processed or red meat, smoking, low calcium intake, and not consuming enough whole grains, vegetables, and fruits.

Some of the risk factors for CRC cannot be changed like a family history of colorectal cancer, chronic inflammatory bowel disease, and inherited genetic conditions.

Potential signs of colorectal cancer include blood in the stool, constant tiredness, change in bowel habits, general discomfort in the abdomen region like gas pains and bloating, vomiting, and weight loss without any known reason.

Individuals who are diagnosed with CRC can opt for treatment options like surgery, radiation therapy, immunotherapy, chemotherapy, and ablation.

Naveen Athrappully is a news reporter covering business and world events at The Epoch Times.
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