Colorectal cancer in young patients shows distinct cellular, genetic traits
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The gist
A Mass General Brigham-led study of 189 tumors found younger colorectal cancer patients' tumors hold more stromal cells.
US colorectal cancer rates under 50 rose 2.9% a year from 2013 to 2022.
Background
Colorectal cancer is increasingly being diagnosed in people under 50, and the American Cancer Society's 2026 report calls it the leading cause of cancer death in that age group in the US. To find out why, researchers at Mass General Brigham's Gene Lay Institute, Dana-Farber Cancer Institute and the Broad Institute analyzed tumors with single-nucleus RNA sequencing (a method that reads gene activity cell by cell). Ana C. Anderson, a co-senior author and core faculty member of the Gene Lay Institute, said the need to understand the rising rates in younger adults is urgent.
How it unfolded
- Oct 29, 2026The study, described as the largest of its kind, is published in Nature Medicine, analyzing 189 tumors from patients ages 29 to 90+, including 54 diagnosed before age 50, using single-nucleus RNA sequencing on more than 850,000 cells.
- Oct 29, 2026Researchers report that in the most common colorectal cancer subtype, younger patients' tumors had a significantly higher proportion of stromal (connective and supporting) cells relative to cancer cells.
- Oct 29, 2026The team confirms the stromal pattern using gene-activity data from 564 other tumors and computer analysis of stained tissue images from another 712 tumors.
- Oct 29, 2026Younger patients also show higher activity of long non-coding RNAs, many of them 'dark' RNAs of largely unknown function, and gene activity suggesting stronger cell-to-cell signaling that can help cancer spread.
- Nov 2, 2026Becker's Oncology and The ASCO Post report on the study.
Who’s saying what
- Expert
- Co-senior author Ana C. Anderson said the findings do not yet explain why more young people are developing colorectal cancer but provide new avenues to investigate.
- Expert
- Co-senior author Kimmie Ng said the results offer a roadmap for investigating distinct features of young-onset colorectal cancer toward new prevention, diagnosis and treatment strategies.
- Caution
- The ASCO Post noted the findings do not yet prove these differences cause more aggressive disease, and that some analyses used smaller tumor subsets and could not account for all confounding clinical factors.
Still unverified
The ASCO Post noted the study did not establish a relationship between stromal composition and chemotherapy resistance in early-onset colorectal cancer; whether immune responses differ across ages also remains an open question because the methods captured relatively few immune cells.