Colorectal cancer—especially in more advanced stages—is increasingly becoming a young person's disease, according to a study published January 26 in Cancer Epidemiology, Biomarkers & Prevention. The new research points to the need of earlier screening initiatives for younger people who are experiencing symptoms or have a family history of disease.
Excluding skin cancers, colorectal cancer is already the third most common cancer in the US, and the American Cancer Society (ACS) estimates over 100,000 new colon cancer cases for 2022. Though it has primarily been thought of as a disease that impacts people later in life—a testament to the previous screening age limit of 50 years old—the number of new cases in older adults is falling, as those in young adults are on the rise, the ACS says.
While the rise of colorectal cancer in young adults isn't necessarily news, what sets this new research apart from previous studies is its focus on two things: the shifting proportions of distant-stage cancers—or those that have metastasized—over time, and special attention to adenocarcinomas, a subtype of colorectal cancer screening and prevention methods are designed to catch, Jordan Karlitz, MD, a visiting associate professor of Medicine-Gastroenterology at the University of Colorado-Denver and senior author of the new study, tells Health.
The news of increasing colorectal cancer rates is alarming—particularly when it affects those younger than the new screening recommendation age of 45 years old. Here, experts in the field of colorectal cancer help parse out the new findings, explain what to know about current screening recommendations, and point out early signs of disease to watch for.
What new colorectal cancer trends did the research find?
For the study, Dr. Karlitz and colleagues analyzed 16 years of adenocarcinoma data from the 2000-2016 Surveillance Epidemiology and End Results (SEER) on 103,975 patients representing 106,871 colorectal cancer cases. The team analyzed trends based on the stage (in situ, regional, local, distant), age (20-54-year-olds), area (colon, rectal, or combined colorectal), and race (non-Hispanic whites, non-Hispanic Blacks, and Hispanics). Because of a low number of cases for American Indian/Alaskan Native and Asian or Pacific Islanders, these races/ethnicities were excluded from the study. To calculate the change over time in incidence rates and shifts in cancer stage proportions, the team also pooled together three years of data between 2000-2002 and 2014-2016.
What the researchers found was that the rate of in situ adenocarcinoma cases—meaning cases in which the cancer hadn't spread—in most age groups and subsites decreased over time. But regional adenocarcinomas—meaning those that had spread to nearby tissues or organs—showed a statistically significant increase in most subsites, with the greatest increase in the rectal area. But metastatic or distant-stage cancers—meaning cases in which the cancer had spread to distant parts of the body—showed the highest increase in cases over time in most age groups.
Specifically, the study showed that cases of distant adenocarcinomas in only the colon rose most in adults ages 30–39, with a 49% increase between 2000–2002 and 2014–2016. During those same years, young adults ages 20–29 saw the steepest rise in rectal-only distant adenocarcinomas with a 133% increase. Adults ages 30–39 were next, with a 97% increase in rectal-only distant disease, followed by a 48% increase in those ages 40–49.
The researchers also calculated distant stage proportions—the percentage of distant-stage disease accounting for all cancer stages. Results showed the proportion of distant-stage disease also increased over time.
The greatest proportional increase occurred in rectal cancers. Young adults between 20 to 29 jumped from 18% to 31% for rectal-only distant stage disease. In adults 30 to 39 years of age, the team observed a steep increase of 20% to 29%. All age groups showed an increased proportion of distant colorectal cancer stages. However, adults 30 to 39 and 40 to 49 made up the highest proportion of colon-only and rectal-only distant stages over time.
The findings surprised the researchers: "We were expecting to see an increased rate of distant stage or metastatic cancers, but the degree to which the rate of distant stage disease was rising over time was more than we expected," Dr. Karlitz explains.
While the researchers found an increasing burden of distant stage disease in all young adults, it was highest among young non-Hispanic Black (NHB) and Hispanic subgroups. NHBs ages 20–29 had the largest proportion of rectal-only distant-stage cancer, rising from 0%–46%; for Hispanics in the same age group that number rose from 28%–41%. The proportion of distant-stage colon cancer increased the most for NHBs as well, from 20%–34%.
Future research should address these startling increases, Dr. Karlitz says: "Moving forward, we need to focus on interventions and research to better understand why we're seeing a greater burden in non-Hispanic Black and Hispanic groups."
When should you get screened for colorectal cancer?
The study findings support the recent changes to the screening guidelines for colorectal cancer from both the ACS and the US Preventive Services Task Force, which recommend that screening for the disease should start at age 45 for everyone with an average risk—that means they do not have a personal or family history of colorectal cancer, nor do they have a history of inflammatory bowel disease (IBD), a suspected or confirmed hereditary colorectal cancer syndrome, or a history of radiation to the abdomen.
"The previous guideline said to start at age 50, but it was reduced to 45 because there's been a five- to six-fold increase among people under 50 being diagnosed with colon cancer," Anton J. Bilchik, MD, a professor of surgery and chief of medicine at Saint John's Cancer Institute, who was not involved in the study, tells Health.
If the colonoscopy is normal, the next screening can occur in five to 10 years—this lasts up to age 75, after which they're done on an as-needed basis decided by your doctor. No one past age 85, however, should be screened for colorectal cancer, per the ACS. If a screening identifies precancerous polyps, however, your doctor may schedule an earlier follow-up as early as every one to three years.
A colonoscopy, a procedure during which your doctor inserts a tube with a camera on it into the rectum and up through your large intestine to check for warning sings of cancer, is the gold standard for colorectal cancer screenings, but if you find it too invasive, your doctor may order a virtual colonoscopy. A virtual colonoscopy is a CT that takes images of the inside of your colon. The catch is that if the images show a sign of cancer or polyps, you may still need a regular colonoscopy as a follow-up.
Early screening helps to identify and remove any polyps, stopping them from turning into cancer. With regular screening, colon cancer is preventable in about 70–80% of people who practice good nutrition and regular exercise, says Dr. Bilchik, explaining, "Most colon cancer is curable. The people with the least curable cancer are those that, by the time they are diagnosed, already had cancer spread to other organs."
When to speak with your doctor about symptoms
If you're having symptoms related to colon cancer—vomiting, bloody stools, or severe abdominal pain—it's crucial to discuss them with your doctor, experts warn.
"If you're having symptoms, you want to tell your provider so you could try to figure out what needs to be done next. You'll also want to be proactive about knowing your family history as that's an opportunity to get earlier screenings," explains Dr. Karlitz.
Rectal bleeding, which can be a sign of colorectal cancer, can mask as hemorrhoids or another health condition. While bright-red blood is a telltale sign of hemorrhoids, if the bleeding is darker or maroon-like, it could signal bleeding in the upper intestinal tract and potentially colon cancer. Regardless, the symptom is worth mentioning to your physician. Another early sign of colorectal cancer is weight loss. Though weight fluctuates all the time, continued weight loss or a persistent loss of appetite could signal a bowel obstruction.
If your symptoms are severe enough, your doctor might recommend a colonoscopy even if you aren't old enough for recommended screening. The key here is getting to the doctor immediately instead of dismissing your symptoms. "The increase we're seeing in younger patients regarding higher rates of distant-stage, early-onset colorectal cancer may be because of delayed diagnosis," says Dr. Karlitz. "So, be proactive about acting on your symptoms and relay your symptoms to your provider as soon as possible."
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