Colorectal cancer is rising in people under 50, and they often do worse despite being younger and healthier. A study published this week in Nature Medicine offers a new clue. The soil may matter as much as the seed.
The team, from Dana-Farber and the Broad, mapped gene activity in more than 850,000 individual cells from 189 colorectal tumors, in patients from their late 20s to their 90s. In the most common subtype, tumors from younger patients held a higher proportion of connective and supporting tissue relative to cancer cells. That tissue can suppress immune attack and shield cancer cells from chemotherapy. Younger tumors also showed more signaling tied to invasion, and more activity from long non-coding RNAs, much of it with no known function yet.
This fits what we already knew. Prior genomic comparisons show early-onset and later-onset colorectal cancers share broadly similar mutations, and earlier work found that the poor-prognosis subtypes of colorectal cancer are defined largely by gene activity in the surrounding stroma rather than in the cancer cells.
Integrative oncology has always lived in the soil: inflammation, insulin signaling, the gut microbiome, what reaches the colon lining every day. These are things we can actually shift. I am glad to see diet and gut bacteria are the next thing the researchers plan to test.
This study shows association, says nothing yet about survival, and does not explain why more young people are getting colorectal cancer. It helps explain why their tumors may behave differently.
So what can you do about your own terrain? Here is where I would start.
Know the signs and take them seriously. Rectal bleeding, a change in bowel habits, belly pain that does not go away, and unexplained iron deficiency all deserve a workup at any age.
Know your screening options. Screening now starts at 45, and earlier if colorectal cancer runs in your family. Colonoscopy is still the most complete test because it finds and removes polyps in the same visit. If you are not ready for one, stool tests are a good place to start: FIT once a year, or a stool DNA or RNA test such as Cologuard Plus or Colosense every few years. CT colonography is another option. A blood test called Shield is available for people who decline everything else, but it misses more polyps and early cancers. Any positive result from a test other than colonoscopy means a colonoscopy comes next, so have that plan in place before you test.
Know your family history. About 1 in 6 people diagnosed with colorectal cancer before 50 carry an inherited gene variant, most often Lynch syndrome. If colorectal or uterine cancer runs in your family, ask about genetic counseling.
Feed the microbiome. Fiber is food for the bacteria that protect the colon lining, and whole grains are one of the best sources. I like starting meals with bitter greens or vegetables before protein, and eating a wide variety of plants across the week.
Protect your gut bacteria. Frequent antibiotic use has been linked to early-onset colorectal cancer in observational studies. Use them when you truly need them.
Keep blood sugar steady. Insulin resistance and excess weight come up again and again in the research on early-onset colorectal cancer, and sugar-sweetened drinks are one of the most consistent signals. Cutting liquid sugar is a simple place to begin.
Eat less processed and red meat, and fewer ultra-processed foods overall.
Cut back on alcohol. It is one of the most firmly established dietary risks for colorectal cancer, and less is better.
Check your vitamin D. In the largest pooled analysis, colorectal cancer risk was lowest at blood levels of about 35 to 40 ng/mL. I aim higher with my patients, around 50 to 70 ng/mL, for benefits beyond the colon.
Move through the day. Long hours of sitting have been linked to early-onset colorectal cancer too.
We are still learning why colorectal cancer is rising in young people. We already know a lot about lowering the risk.
Ksenia Malarkey, ND is a naturopathic physician specializing in integrative oncology, hormones, and metabolic health.
She provides medical care for Washington and Oregon residents and offers global health coaching.
To schedule a free 15-minute consult, visit drkseniamalarkey.com