Speaking Out: A Rising Concern of Colorectal Cancer Risk in Younger Adults

May 22, 2020

As the risk of colorectal cancer grows among those under 50, younger adults should know more about signs and screening.

Historically, colorectal cancer (CRC) primarily affected older people. But in the 1990s, a puzzling new trend began: As the disease rate dropped in people over age 50, it rose fairly rapidly in younger adults.

The trend continues today with no signs of abating, and researchers are working to determine whether factors such as diet and a sedentary lifestyle play a role or if a unique new subtype of the disease is striking younger adults. Questions are also arising about how best to diagnose and treat CRC in this younger population.

Dr. Zsofia K. Stadler, an oncologist with Memorial Sloan Kettering Cancer Center in New York City and co-director of the annual Early Age Onset Colorectal Cancer Summit hosted by the Colon Cancer Foundation, a patient advocacy group, sat down with CURE® to delve into those issues.

CURE®: Please tell us about the rise of CRC in younger adults.

Stadler: Since the 1990s, we’ve had guidelines for colonoscopy screening for patients over the age of 50. And in fact, we have seen a slow but steady decrease in colon cancer risk in the over-50 population. This is because colonoscopy detects and removes premalignant polyps, thus preventing cancers.

But what has become quite striking is that, since the 1990s, the incidence of colon cancer in the under-50 population, which doesn’t usually get colonoscopies, has been increasing annually by about one to two percentage points, which is quite a large increase. And that increase is even more profound in very young patients. In those 20 to 29, the increase is approximately 4% annually — wow!

Another trend involves younger adults receiving diagnoses at later stages. Why is that?

We don’t exactly know the answer. One hypothesis is that maybe the biology of some of these cancers is more aggressive, but most of the data that has been presented does

not demonstrate that. Later diagnosis may also just be due to patients presenting at later stages because they’re not undergoing routine screening.

Some interesting research suggests that the later diagnosis is due to actions by both the provider and the patient. For example, it’s known that patients with early-onset colon cancer wait up to a year after presenting with symptoms to seek medical attention. In addition, the average number of providers that an early-onset colon cancer patient sees prior to diagnosis is three, and the reason is that, often, the symptoms are dismissed as hemorrhoids or hemorrhoidal bleeding, which is quite common.

What are other possible signs of CRC?

Other symptoms can include rectal bleeding, changes in bowel habits — either diarrhea or constipation — and abdominal pain. Any of these can be symptoms if they occur over time or are progressively getting worse.

Are there differences between young-adult CRC and the disease in older adults?

We know that, in younger adults, more of the colon cancer is genetic, meaning that an inherited genetic mutation is causing a predisposition to it. The most common hereditary cause is Lynch syndrome, which overall accounts for about 3% of CRC cases. But in the young patients under 50, it accounts for about 10% of all colon cancer diagnoses.

About 80% to 85% of younger-adult colon cancers are not linked to heredity, and that leaves the rest unexplained. A lot of research has looked into epidemiological factors that may be associated with the increased risk, but, interestingly, although we know of many risk factors that increase average-onset colorectal cancer — Western diet, obesity, diabetes, smoking, excessive alcohol consumption — those don’t seem to account for the rise. So, we are still very much investigating the causes of this dramatic shift.

Due to the rise of the disease in younger adults, the American Cancer Society now recommends earlier screening for CRC. What are its recommendations?

The American Cancer Society did a modeling study that demonstrated that perhaps we should lower the average age at which we begin screening from 50 to 45. In fact, in African Americans, for example, this has been a recommendation for quite a while now.

The studies seem to suggest that we’ll pick up more cases by expanding screening this way, but because the most dramatic increase in colon cancer in young patients is actually in the age group of 20 to 29, we won’t necessarily be targeting the group where the increase in risk is the most dramatic.

If we’re not screening the younger adults who are most at risk, how can we stem the rising tide of disease?

Many families also have polyps that increase the risk of colorectal cancer. And there is a lack of knowledge in many families about how many polyps an individual had, at what age and what the pathology of the polyps was, which can be very important for determining the risk a certain patient faces.

One of the most important predictive aspects is that, in 15% to 25% of patients, there’s a family history of the disease, which raises risk. That’s why the United States Preventive Services Task Force put out recommendations that anyone with a first-degree relative who got colon cancer at age 60 or under should get colonoscopy screening starting at age 40. However, I don’t think we always follow those guidelines, and patients may not be aware that earlier-age screening is recommended for them.

Sometimes primary care physicians don’t even start to talk about colon cancer risk until age 50, at which time they usually start colonoscopy screening, but in some individuals, a primary care physician who was aware of the family history might have initiated colonoscopies sooner.

So, patients need to know that, if there’s a new diagnosis in the family, they should inform their primary care physicians. But at the same time, the primary care physicians should be asking the patients every once in a while: “Is there anything new going on in your family? Has anyone been diagnosed with cancer?” Because sometimes, these family histories change, and you could uncover a genetic predisposition syndrome.

When someone does develop colorectal cancer, it’s now routine for doctors to check the tumor for mutations, some of which can indicate the presence of a syndrome that predisposes patients to colorectal and other cancers. Having this information allows healthy relatives to undergo careful screening for cancer over time, so that any disease is caught and treated early.

You mentioned colonoscopy. Are there any other screening types that would be appropriate for younger adults?

There are other types of screening, but none are as good as colonoscopy. There is a sigmoidoscopy, but that screens only the left side of the colon, missing the entire right side. Hemoccult or guaiac tests that look for blood in the stool are better than nothing, but if someone has symptoms of rectal bleeding, our recommendation is really solid to get a colonoscopy.

What’s your most important advice for a young adult who’s facing a CRC diagnosis?

They should know that they’re not alone as patients and they’re not alone in the field that’s trying to study this. Gastroenterologists, primary care physicians, medical oncologists and surgeons are more and more aware of the rise in early-onset colon cancer. In fact, many larger cancer centers have set up early-onset colon cancer centers where these patients can go to address their unique issues, including social and psychological concerns, fertility and genetics. There are resources for these patients.

Editor's note: The USPSTF requested an update to this article. For clarification, the Task Force recommends screening for colorectal cancer in adults aged 50 to 75 years. And for adults aged 76 to 85 years, the decision to undergo screening should be an individual one.


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