Colon cancer looks different in young people — and often more aggressive, a new study found

• A new study explored the differences between tumors in younger and older colon cancer patients.
• Younger patients sometimes had more aggressive, treatment-resistant forms of colon cancer.
• Staying active, cutting down on processed foods, and getting screened are good ways to lower risk.

People under 50 aren't only at a higher risk of colon cancer today than they were a few decades ago. They're also developing a different, sometimes more aggressive form of it compared to older patients, scientists say.

A new study published in Nature Medicine analyzed 189 tumors from colorectal cancer patients aged 29 to 94, including measurements of gene activity in more than 850,000 cancer cells.

The goal was to look at how tumors varied "across the entire spectrum of age," Dr. Ana Anderson, a co-senior author of the study who leads the cancer immunology program at the Gene Lay Institute at Brigham and Women's Hospital in Boston, told Business Insider. "Is it the same colon cancer but just happening in younger people, or is there something different about it?"

As a result, the study was able to map out gradual, subtle differences in colorectal cancer tumors correlated with age. While the researchers couldn't pinpoint exactly why tumors in younger people look different, Anderson said the study is an exciting starting point for further research.

"There's a lot of interest in lifestyle factors and environmental exposures as potential contributors; however, nothing specific has been pinned down," Anderson said. "What we did is take a rather simple but comprehensive approach just to try to understand the disease itself."

Younger patients' tumors had a different cellular makeup

The study's researchers couldn't definitely state that colon cancer in younger patients is always more aggressive — that would require more study.

However, what they did find was that younger patients "generally have more aggressive disease and they are generally more resistant to the standard of care therapies, which is mostly chemotherapy," Anderson said.

Tumors in younger patients generally had a higher presence of supporting and connecting cells known as stromal cells. Stromal cells, such as fibroblasts, can produce factors that suppress the immune response, making it harder for chemotherapy drugs to work. "They essentially can form a shield that protects the tumor from infiltration," Anderson said.

The study found that the presence of stromal cells generally declined from younger to older patients, and the youngest patients tended to have the highest number of stromal cells in proportion to cancer cells.

The reverse was true for the oldest patients, who generally had the fewest stromal cells and the highest numbers of cancer cells.

Researchers narrowed down where to look for answers

Younger patients also had higher activity of long non-coding RNAs (lncRNAs), which are associated with cellular signaling in cancer. The study also found gene activity in younger patients that suggested stronger signaling between cells — potentially helping cancer cells move and invade nearby tissue.

The problem is, lncRNAs are still a fairly recent discovery; they only became linked to cancer research in the late 2000s, with some poorly understood ones referred to as "dark RNAs." "A lot of them have just not been researched, and that's why they're called 'dark RNAs' — it's a big mystery," Anderson said.

For that reason, she said it was the finding she considered most promising. "There's a world of biology to be discovered there — we know where to focus our research efforts," she said.

Anderson, an immunologist, also hopes to explore the presence of immune cells in younger colon cancer cases, as immune cells are involved in killing cancer cells but were "under-captured" in this study, she said. "There are many types of immune cells," she said. "Are there different subsets that are more present in the young tumors or absent in the young tumors versus the older tumors?"

Reduce your risk with these simple habits

While the study doesn't present any immediate new takeaways for young people concerned about colon cancer, Anderson suggested following existing guidance for lowering your risk.

She noted that the recommended screening age for most people was lowered from 50 to 45 a few years ago, but that it's wise to see a doctor sooner if you experience common colon cancer symptoms like rectal bleeding, abdominal pain, bloating, or changes in bowel movements.

If you're "extra cautious," she said, it's never a bad idea to stay active and cut down on inflammatory foods such as ultraprocessed snacks and alcohol.