More young adults are getting colorectal cancer. What makes their tumors different?

Key Points:

• A study published in Nature Medicine reveals that colorectal cancers in patients under 50 differ from those in older patients in cellular composition and gene activity, with younger patients' tumors having a higher proportion of stromal (supporting) cells relative to cancer cells.
• Researchers mapped gene activity in over 850,000 cells from 189 tumors and found that these differences might explain why colorectal cancer can behave more aggressively in younger adults, who are often diagnosed at a more advanced stage.
• The study identified increased expression of long noncoding RNA molecules, including poorly understood "dark RNA," in tumors from younger patients, and stronger cell communication pathways related to tumor invasion and blood vessel formation.
• Despite rising colorectal cancer incidence in younger adults, routine screening protocols typically start at age 45 or 50, contributing to delayed diagnosis; experts emphasize the importance of early detection and suggest revisiting screening guidelines.
• While the findings offer new insights into tumor biology and potential treatment targets, researchers caution that further study is needed to determine whether these molecular differences cause increased aggressiveness or treatment resistance in younger patients.