Study reveals colorectal cancer in younger patients shows distinct cellular patterns

Researchers from Mass General Brigham, Dana-Farber, and the Broad Institute published a landmark single-nucleus RNA sequencing study analyzing 189 colorectal tumors in Nature Medicine on October 29, 2026. Evaluating over 850,000 cells across patients aged 20 to 90+, the team discovered that tumors in patients under 50 contain significantly higher proportions of connective stromal cells linked to chemotherapy resistance and heightened invasive signaling. The findings offer key biological clues into why early-onset colorectal cancer—now the leading cause of cancer death among Americans under 50—presents more aggressively and resists treatment.

Rising colorectal cancer incidence

• ▪According to the NEJM Evidence study, colorectal cancer incidence among Americans aged 45 to 49 rose by 12.76% annually from 2019 to 2023.
• ▪Colorectal cancer diagnosis rates in the United States among people under age 50 rose nearly 3 percent per year from 2013 through 2022, according to the American Cancer Society.
• ▪A study published in NEJM Evidence found that colorectal cancer incidence rates in the United States rose across age groups up to ages 65 to 69

Mortality and late-stage diagnosis in younger patients

• ▪Younger colorectal cancer patients are 58% more likely than older patients to be diagnosed at advanced stages, contributing to treatment challenges and lower survival relative to baseline health.
• ▪The American Cancer Society identified colorectal cancer as the leading cause of cancer death among people under age 50 in the United States.

Scope of the single-nucleus tumor atlas

• ▪The Nature Medicine tumor atlas analyzed gene activity across 850,222 high-quality nuclei from 54 early-onset and 135 average-onset colorectal cancer tumor specimens.
• ▪In the Nature Medicine tumor atlas cohort of 189 patient specimens, 84.9% of cells were epithelial, 5.6% were stromal, and 3.1% were myeloid cells.
• ▪Researchers from Mass General Brigham, Dana-Farber Cancer Institute, and the Broad Institute published a single-nucleus RNA sequencing atlas of 189 colorectal tumors

Biological features of early-onset tumors

• ▪The Nature Medicine study found that early-onset colorectal cancer tumors were significantly less likely to be classified as the CMS1 consensus molecular subtype compared to average-onset tumors.
• ▪In the Nature Medicine study led by Caroline Porter, tumors in younger colorectal cancer patients had a significantly higher proportion of connective and supporting stromal cells relative to cancer cells.
• ▪Younger colorectal cancer patients in the Nature Medicine study exhibited higher activity of long non-coding RNAs and gene activity suggesting stronger cell signaling that helps cancer cells move and invade tissue.