The longer a person stays overweight, the more likely they are to develop colon cancer, according to new research. Scientists likened it to the “cumulative effects of smoking” on lung cancer.
The alarming report from researchers at the German Cancer Research Centre and Heidelberg University adds another layer of concern for individuals who have struggled with obesity or problems with excess weight throughout their lives. The finding is based on more than 10,000 people tracked for almost two decades.
Those with a body mass index (BMI) of over 25 were two-and-a-half times more prone than peers who maintained a healthy BMI. A healthy BMI is between 18.5 to 24.9.
Cases among participants who carried extra pounds for a few years increased by 25 percent. Rates rose directly in tandem with the amount of time spent out of shape.
The study, published in JAMA Oncology, shows unhealthy lifestyles are a bigger factor than previously feared.
“The results of this case-control study suggest a greater role of cumulative lifetime excess weight of colorectal cancer risk than estimated by traditional analyses based on BMI measures taken at a single point in time,” the authors write.
Researchers say these ranged from four to 27 percent depending on how high they were.
Colon cancer is the third most common cancer among adults in the U.S. It’s estimated to be the cause of death for nearly 53,000 Americans in 2022, according to the American Cancer Society.
It is believed fat triggers tumors by secreting chemicals which cause inflammation. In recent years obesity has been linked with a seven to 60 percent increased risk of colon cancer, also referred to as bowel cancer in Europe.
“The findings in our study were consistent with these previous studies when BMI was considered only at a single point of time. However, few studies have evaluated the associations looking at BMI at various points of time during the life span,” the authors write. “We considered BMI at various ages and found excess weight between 20 and 70 years to be associated with colorectal cancer risk in a clear dose-response manner.
“The observed associations suggest having overweight or obesity since a young adult age is a persistent risk factor throughout the adult lifespan,” the paper continues. Consideration of cumulative exposure to excess weight throughout the life span is essential to disclose its full effects.”
The proposed concept is similar to how cigarettes increase the risk of lung cancer and other tumours linked to smoking.
“Calculation of cumulative lifetime exposure has become a standard measure for other risk factors. For example, pack-years are widely used as a measure of lifetime cumulative smoking exposure and have been shown to be associated with the risk of a variety of smoking-related diseases, including multiple cancers,” the paper explains. “By contrast, such measures have not been widely used for other risk factors, such as excess weight.”
At least 300 million adults are obese and 1.4 billion overweight, according to the World Health Organization. Excess weight is linked with more than a dozen different types of cancer – as well as cardiovascular disease, diabetes and even dementia.
Report by South West News Service writer Mark Waghorn