Even though young patients with metastatic colorectal cancer tend to be more fit and receive more intensive treatment than older patients, both groups survive for roughly the same amount of time, according to a new study by Dana-Farber Cancer Institute investigators.
The findings, published in the Journal of the National Cancer Institute, come as colorectal cancer rates are rising markedly in young people. The study’s researchers said the results are somewhat surprising, as younger patients, who usually have fewer complicating health factors, might be expected to survive longer than older patients, according to a Dana-Farber press release.
The study drew on data from the CALGB/SWOG 80405 clinical trial, which tested a combination of chemotherapy and biologic therapy in patients with metastatic colorectal cancer. Researchers compared survival times in 514 trial participants who were younger than age 50 with the survival times of 1,812 patients above 50.
The median survival for patients with young-onset colorectal cancer was 27.07 months vs. 26.12 months for the older-onset group. Progression-free survival – how long patients lived before the cancer worsened – was also similar for the two groups: 10.87 months for the younger patients vs. 10.55 for the older ones.
Confounding expectations even further, the investigators found that patients under age 35 had the shortest median overall survival of any age group: 21.95 months vs. 26.12 months in older-onset patients. Because the study included relatively few patients younger than 35, the difference is not considered statistically significant, researchers said, but it aligns with previous research suggesting that very young patients have worse outcomes.
The findings underscore how much there is still to be learned about young-onset colorectal cancer. Cases are markedly on the rise: between 2000 and 2013, incidence of the disease in people under age 50 increased approximately 22%, even as overall incidence of colorectal cancer has declined. Despite a wellspring of new research, no definitive cause for the increase has been found.
The finding that younger patients fare no better than older patients, despite having several factors in their favor, might suggest that colorectal cancer is more aggressive at an earlier age. However, there’s no conclusive evidence that that is the case.