Is This Gene Behind the Rise of Early-Onset Colon Cancer?

Colorectal cancer is no longer just a disease of older adults. While colon cancer cases are decreasing across the population, cases in people under 50 are steadily rising. Experts like Daniel Sussman, M.D., MSPH, are sounding the alarm.

“It’s pretty clear this shift is happening at younger ages,” says Dr. Sussman, a gastroenterologist and colorectal cancer expert at the Sylvester Comprehensive Cancer Center and the University of Miami Health System.

The rate of early-onset colorectal cancer is expected to double by 2030, with 10.9% of all colon cancers and 22.9% of all rectal cancers diagnosed in young adults, according to a study from the American College of Surgeons.

The more common type of colorectal cancer that younger patients are getting in their lower GI tract is rectal cancer. For some of these cases, colorectal cancer is caused by an inherited condition called Lynch syndrome, which is caused by a gene mutation.

What is Lynch syndrome?

Lynch syndrome is a hereditary condition that increases your risk of developing certain cancers, especially colorectal and endometrial (uterine) cancer, often at a younger age than usual. It’s caused by a change, or mutation, in one of the genes that normally helps fix mistakes in DNA. These DNA repair genes act like spellcheckers in our cells, and when they don’t work properly, harmful changes can build up over time and lead to cancer.

Having Lynch syndrome doesn’t mean you will develop cancer. It does mean you should take extra preventative measures and get screened for cancer earlier to either prevent it or catch it early when it’s most treatable.

An estimated 1 in 279 individuals in the United States are Lynch syndrome carriers. Children of parents with the gene have a 50% chance of also having it. Most people with the inherited gene don’t know they have it.

Who should get tested for Lynch syndrome?

Lynch syndrome runs in families, so if close relatives have had colon, uterine or other related cancers — especially before age 50 — genetic testing can help determine your risk and guide next steps for screening or prevention.

Many people undergo testing for Lynch syndrome when a close relative is diagnosed with the gene. When a patient is diagnosed with colorectal cancer, their tumor is tested for indicators of Lynch syndrome.

“If a tumor is missing certain repair proteins, that triggers a referral for genetic testing for the patient and all first-degree relatives. That’s how many people are first diagnosed with Lynch syndrome,” says Dr. Sussman.

Other causes for early-onset colorectal cancer

Heritable conditions, like Lynch syndrome, account for only 10% of colorectal cancers. Lifestyle factors may drive the rest, although researchers are still studying the cause of early colorectal cancer.

“Most researchers think a large portion of early-onset colorectal cancers has to do with teenage obesity. And even more important than obesity might be food choices made in childhood,” says Dr. Sussman.

Possible lifestyle causes of colorectal cancer

At the Gastrointestinal Cancer Prevention Clinic at Sylvester, Dr. Sussman has observed telling patterns among patients diagnosed with colorectal cancer at younger ages. “A lot of the young men I see with rectal cancer have a history of smoking or eating a lot of fast foods and ultra-processed foods,” he says.

Research shows that eating a lot of processed meats, like deli meat, beef sticks, bacon and hot dogs, has cancer-causing effects.

“People who regularly eat those deli-style meats have much higher odds of developing colorectal cancer. The odds ratio is through the roof,” says Dr. Sussman.

Instead, Dr. Sussman recommends eating a Mediterranean diet that is rich in whole, plant-based foods. These include fruits, vegetables, legumes, whole grains, nuts, olive oil, moderate amounts of fish and dairy, and minimal red meat and processed foods.

High-fiber diets are also helpful for preventing colorectal cancer.

Screening guidelines: Is 45 early enough?

In May 2021, the U.S. Preventive Services Task Force (USPSTF) lowered the recommended screening age for average-risk adults from 50 to 45 because of the increase in early-onset colorectal cancer.

Those with a parent or sibling diagnosed with colorectal cancer should begin screening even earlier. “If you have a first-degree relative with colon cancer, you should start screening at 40, or 10 years before the age that relative was diagnosed –– whichever comes first,” says Dr. Sussman.

This is especially critical for people with Lynch syndrome. Cancer screening is typically more frequent for these individuals and begins earlier than for the general population. Recommendations vary slightly depending on the specific gene mutation, but screening can begin as early as your 20s.

The gold standard for screening

Whether you have Lynch syndrome or not, getting a colon cancer screening on the schedule your doctor recommends for you is the gold standard for preventing colorectal cancer. Precancerous polyps can be removed during colonoscopies before they become cancerous.

Once patients have signs of colon cancer, such as rectal bleeding, unexplained weight loss or unexplained anemia, colorectal cancer may already be more advanced. “Most people with a large polyp or even early colon cancer don’t have symptoms,” says Dr. Sussman.

Because of the increase in colorectal cancer in younger people, doctors now take the signs of it more seriously in these patients.

“Twenty years ago, if a young person came in with a little rectal bleeding, we treated it like hemorrhoids. Now we know better. If bleeding is persistent, it needs to be investigated,” says Dr. Sussman.

Prevention for everyone — Not just Lynch syndrome patients

Whether or not you have a genetic predisposition for colorectal cancer, many of the same lifestyle changes can help reduce your risk:

• Quit tobacco (including vaping)
• Limit alcohol
• Maintain a healthy weight
• Stay physically active
• Avoid processed meats and prioritize fiber

Interestingly, one prevention strategy specific to Lynch syndrome has surprising roots in carbohydrate chemistry. Studies show that if you cook pasta or rice and then refrigerate it before eating, some of those simple carbohydrates chemically reform into resistant starches that behave more like fiber in your body. If you cool these resistant starches to eat them at a later date, you get a higher percentage of fiber-like substances rather than just the simple sugars.

“For Lynch syndrome patients, it seems like that high-fiber diet does have a beneficial effect over time,” says Dr. Sussman.

A model for high-risk care

To better serve patients with hereditary risks for colorectal cancer, the Genetic Predisposition Syndrome Clinic at Sylvester offers personalized screening and prevention plans for people with known genetic mutations or a strong family history. Physicians in the clinic operate like a second primary care provider focused entirely on cancer prevention.

Early-onset colorectal cancer is a growing threat, but it’s one that can be mitigated with genetic testing, preventative lifestyle changes and early screening. “We have real tools to prevent cancer from ever starting. And even if you’re not genetically predisposed, making smart choices early in life matters,” says Dr. Sussman.

Written by Wendy Margolin for Syvlester Comprehensive Cancer Center.

Tags: Cancer risk factors, DNA repair genes, Dr. Daniel Sussman, Gastrointestinal oncology, genetic predisposition, Sylvester Comprehensive Cancer Center