By Karim Hammam
Colorectal cancer incidence is increasing across nearly all adult age groups in the United States, reversing a decades-long decline, according to a new analysis of National Cancer Institute data. Researchers say the trend suggests unknown environmental risk factors may be offsetting gains from expanded screening.
Overall incidence climbs after 20-year decline
The analysis, led by Caitlin Murphy of the University of Chicago, found that the overall colorectal cancer rate fell from 55.2 per 100,000 in 2000 to 36.7 in 2022, before rising to 38.3 in 2023. This marks the first increase in the overall rate in more than 20 years. The steepest annual increase, 12.76% from 2019 to 2023, occurred among adults aged 45 to 49, likely driven by more screening after the recommended age was lowered to 45 from 50.
Screening does not explain broader rise
However, increased screening does not account for the rise in other age groups or the overall uptick, indicating that unidentified risk factors, possibly environmental, are at play. Murphy said screening is working as intended by catching cancer earlier, but the underlying causes of the broader increase remain unclear.
Younger patients' tumors show distinct biology
A separate study published in Nature Medicine analyzed 189 tumors and found that younger patients' tumors had more connective and supporting cells relative to cancer cells, a feature linked to chemotherapy resistance. Younger patients also showed higher activity of long non-coding RNAs, many of unknown function, and gene activity suggesting stronger cell signaling that may promote invasion.
Study co-author Ana Anderson of Harvard Medical School said the findings give researchers a new direction to tackle the urgent problem.
Kidney cancer trial shows survival benefit with dual therapy
In unrelated research, a midstage trial found that alternating the targeted drugs Votrient (Novartis) and Avastin (Roche) dramatically improved survival for patients with advanced clear cell renal carcinoma. The 51 patients, all with metastatic disease at diagnosis, received the two VEGF-blocking drugs on an alternating schedule.
Median survival reaches 63 months
Patients survived a median of 63.2 months, including 24.8 months without disease progression. By comparison, Votrient alone typically yields overall survival of 28 to 29 months and progression-free survival of 9.2 months. The benefit was especially strong in favorable-risk patients, where median progression-free survival reached 28.5 months and overall survival 76.9 months.
Study leader Dr. Saby George of Roswell Park Comprehensive Cancer Center said the regimen's benefit was comparable to or better than immunotherapy combinations, at lower cost.
