Why is colon cancer becoming more common in young adults?

Colorectal cancer in young people is rapidly becoming more common. (Getty Images)

March is Colon Cancer Awareness Month, and doctors and health advocates are sounding the alarm about a troubling trend: More younger Americans are being diagnosed with the disease. More worryingly, many cases are advanced, confusing doctors.

Colon and rectum are part of the large intestine. Colon cancer, formally known as colorectal cancer (CRC), typically begins when a mutation occurs that leads to abnormal cell growth. This can lead to the formation of colon polyps, which the Mayo Clinic defines as small lumps of cells that form on the lining of the colon. Initially, these polyps may be benign, but over time they can become cancerous. This type of cancer is known to mostly affect older adults, but is increasingly being seen in younger people around the world.

A recent report by the American Cancer Society highlighted the alarming increase in colon cancer diagnoses among young people. According to the study, the number of Americans under the age of 55 has nearly doubled, from 11 percent in 1995 to 20 percent in 2019. According to some studies, the disease may become the leading cause of cancer death in the United States for people ages 20 to 49. by 2040.

But what is even more worrying for doctors is that advanced diagnoses in young patients are also increasing significantly. According to the report, “60 percent of all new cases progressed in 2019, compared to 52 percent in the mid-2000s.”

To better understand why this is happening, Yahoo News spoke with Dr. Marios Giannakis, a medical oncologist and clinical investigator at the Young-Onset Colorectal Cancer Center, part of the Dana-Farber Cancer Institute​ in Boston. The center treats patients with early-onset colon cancer and also conducts multidisciplinary research to better understand the disease and develop ways to prevent, detect and treat it.

Why is colon cancer increasing in young people?

“This epidemic of young-onset colon cancer is still fairly recent and still largely unexplained,” Giannakis told Yahoo News.

He explained that early-onset CRC has some unique characteristics. It tends to be more aggressive and often occurs on the left side of the colon rather than the right, and some patients with this type of cancer experience abdominal pain or rectal bleeding. However, he noted that many patients may not have symptoms.

Why CRC cases are on the rise in people under 50 is a perplexing question that remains unanswered, and one, Giannakis said, which emphasizes the need for continued research. But there are some clues as to why this might be happening.

Experts believe that lifestyle risk factors may contribute to the increased incidence of early-onset CRC. Younger Americans experience more obesity and lead more sedentary lives. According to experts, they also consume larger amounts of processed and sugary foods. All of these factors are known to increase the risk of colon cancer.

According to the American Cancer Society, 55% of all CRCs are linked to lifestyle factors. However, the organization points out that the strongest risk factor for the development of the disease is its presence in the family.

Environmental exposures have also been linked to young-onset CRC, Giannakis said.

“One of the ideas that follows the epidemiological trends of this phenomenon that really happened since the 90s … is the so-called birth cohort effect,” he said. “What this basically means is that some risk factor, or maybe a combination of risk factors, in the environment is just being passed on to the younger generations because the younger generations are just more exposed to it,” he added.

But Giannakis said lifestyle and environmental factors don’t tell the whole story.

“There may be other things that we don’t quite understand about the molecular types of cancers, the cancers themselves, but also the microenvironment cancer, [or] what surrounds these early-onset tumors,” he said.

Studying the microbiome—the community of microorganisms, primarily bacteria, found throughout the human body, especially in the gut—is one of the research areas Giannakis’ team focuses on. One question they hope to answer, he said, is “if our gut microbiome changes in a way that facilitates colon cancer.”

According to the Dana-Farber Cancer Institute, recent studies have shown that these bacteria can influence the development of CRCs and also how they respond to treatments.

In a new paper published in the journal Science co-authored by Giannakis, Dana-Farber Cancer Institute researchers outlined the types of research needed to better understand the underlying causes and biology of CRC in young adults. The authors noted that this research should look at a combination of things like genetics, environmental and lifestyle factors, people’s immune systems and the environment in which these cancers grow.

Chart showing trends in colorectal cancer incidence rates in the United States from 1998 to 2019 by age and sex.

Colorectal cancer could become the leading cause of cancer death in the United States by 2040 among 20-49 year olds, according to experts. (Yahoo News Photo Staff)

Where in the US are younger people diagnosed with colon cancer?

A recent Cleveland Clinic study provides some insight into where young-onset CRC cases and deaths appear to be more common in the United States

“Among the youngest patients, we found significant hot spots in the Midwest and also in the Great Lakes region,” Cleveland Clinic researcher and study lead author Blake Buchalter said in a statement. In addition to finding these hot spots, the research team located three places where young-onset colon cancer is less common: the Southwest, California, and the Mountain West.

The researchers said it’s unclear why colon cancer in young people is more common in certain areas of the country, but they plan to do more research to find answers.

But we know who in the population is at greater risk. According to new data from the American Cancer Society, the disease disproportionately affects three U.S. population groups — American Indians, Alaska Natives and Black Americans — and has the highest number of diagnoses and deaths of any group in the country.

How can people lower their risk of colon cancer?

The Centers for Disease Control and Prevention says that the most effective way to reduce a person’s risk of colon cancer is to get screened routinely. The age at which a person in the average risk group must be screened was calculated in 2021 from 50 years to 45 years. However, some individuals, such as those with a family history of CRC and black Americans, should consider doing it earlier. The American College of Physicians recommends that black men and women get their first screening at age 40.

According to Giannakis, the gold standard for colon cancer screening is colonoscopy. The test can visualize where polyps are located in the colon, and doctors can remove most of these and some cancers during the procedure. However, most people under the age of 45 are not eligible for a colonoscopy, so experts believe that lowering the screening age in the future may be necessary to prevent cancer in those in their 20s or 30s.

In addition to colonoscopy, other types of screening tests are available in the United States. The CDC recommends consulting with your doctor to determine which one is best for you.

To reduce the risk of developing CRC, the agency recommends a healthy diet that is “low in animal fats and high in fruits, vegetables, and whole grains.” Increasing physical activity, maintaining a healthy weight, and reducing alcohol consumption and smoking can also reduce a person’s risk of developing this type of cancer.

Finally, Giannakis said that young people should not ignore the symptoms associated with the disease. These can include changes in bowel habits, blood in the stool, abdominal pain and weight loss.

“It is important to listen to our body when symptoms suggestive of cancer appear at a younger age. But when we realize that many of these cancers are asymptomatic, we should really be committed to screening as well and continue to do so,” he said.

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