Why is colon cancer on the rise in young adults?

A patient lies in a hospital bed.

Colon cancer among young people is on the rise. (Getty Images)

March is Colon Cancer Awareness Month, and doctors and health advocates are sounding the alarm about a disturbing trend: More younger Americans are being diagnosed with the disease. What’s more disturbing is that many of the cases are at an advanced stage, leaving doctors baffled.

The colon and rectum are part of the colon. Colon cancer, formally known as colorectal cancer (CRC), usually begins when a mutation occurs, leading to abnormal cell growth. This can result in the formation of colon polyps, which the Mayo Clinic defines as small clumps of cells that form on the lining of the colon. In the early stages, these polyps can be benign, but over time they can become cancerous. This type of cancer is known to mainly affect older adults, but it is increasingly seen in younger people around the world.

The alarming increase in colon cancer diagnoses in young people was highlighted in a recent report from the American Cancer Society. According to the study, rates in Americans under age 55 have nearly doubled, from 11% in 1995 to 20% in 2019. Some studies estimate that the disease could become the leading cause of cancer death in the US for people ages 20-49. by the year 2040.

But what worries doctors even more is that advanced-stage diagnoses in young patients are also rising significantly. According to the report, “60% of all new cases in 2019 were advanced, up from 52% 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, which is part of the Dana-Farber Cancer Institute in Boston. The center provides care for patients with early-stage colorectal 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 quite recent and still largely unexplained,” Giannakis told Yahoo News.

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

Why CRC cases are increasing among people under age 50 is a puzzling question that remains unanswered, and one, Giannakis said, this underlines the need for continuous research. But there are some clues as to why this might be happening.

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

According to the American Cancer Society, 55% of all CRCs are linked to lifestyle factors. However, the organization notes that the strongest risk factor for developing the disease is a family history of it.

Environmental exposure has also been linked to early childhood CRC, Giannakis said.

“One of the thoughts following the epidemiological trends of this phenomenon that’s really been happening since the ’90s … is what’s called the birth cohort effect,” he said. “That essentially means that some risk factor or maybe a combination of risk factors in the environment is just being transferred into younger generations because younger generations are just more exposed to it,” he added.

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

“Could be other things that we don’t fully understand regarding the molecular types of cancer, the cancers themselves, but also the microenvironment of the cancer, [or] what surrounds these early tumors,” he said.

Studying the microbiome β€” a community of microorganisms, primarily bacteria, found throughout the human body, particularly in the gut β€” is one of the research areas Giannakis’ team is focusing on. He said one question they hope to answer is “whether the microbiome in our gut is changing in a way that allows for colon cancer.”

According to the Dana-Farber Cancer Institute, recent studies have shown that these bacteria may play a role in the development of CRCs and also how they respond to treatments.

In a new paper published in Science, co-authored by Giannakis, researchers at the Dana-Farber Cancer Institute outlined the kind of studies needed to better understand the underlying causes and biology of early childhood CRC. This research, the authors noted, 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.

A graph showing trends in US colorectal cancer incidence from 1998 to 2019, by age and gender.

Colon cancer could become the leading cause of cancer death in the US for people aged 20-49 by the year 2040, according to experts. (Yahoo News Photo Staff)

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

A recent study from the Cleveland Clinic provides some insight into where CRC cases and deaths at a young age are more common in the US.

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

Researchers said it’s unclear why colon cancer in young people is more common in certain parts of the country, but they plan to conduct further research to find answers.

But we do know who in the population is at higher risk. Based on new data from the American Cancer Society, three groups in the US population – American Indians, Alaska Natives and Black Americans – are disproportionately affected by the disease, with 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 say the most effective way to reduce a person’s risk of colon cancer is to get screened routinely. The age at which a person at average risk should be screened will be lowered from 50 to 45 in 2021. However, some individuals, such as those with a family history of CRC and black Americans, should consider doing it sooner. The American College of Physicians recommends that black men and women have their first screening at age 40.

The gold standard for colon cancer screening, Giannakis said, is a 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 age 45 are not eligible for colonoscopies, so experts believe lowering the screening age may be necessary in the future to catch cancer in people in their 20s or 30s.

In addition to a colonoscopy, there are other types of screening tests available in the US. The CDC recommends seeing a doctor to determine which is best for you.

To reduce your risk of developing CRC, the agency recommends eating a healthy diet “low in animal fats and rich in fruits, vegetables, and whole grains.” Getting more exercise, maintaining a healthy weight, as well as reducing alcohol consumption and smoking can also reduce your risk of developing this type of cancer.

Finally, Giannakis said young people shouldn’t ignore symptoms associated with the disease. These may include changes in bowel habits, blood in the stool, abdominal pain, and weight loss.

β€œIt is important to listen to our bodies when symptoms suggestive of cancer occur even at a younger age. However, when we realize that many of these cancers are asymptomatic, we really need to stay true to screening and pursue that,” he said.

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