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 in young people are rising. The 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.
“As a group, younger patients are more physically active and have higher performance status and are better able to perform the activities of daily living than older patients. They also tend to be treated with higher doses of therapy and have less severe side effects,” said study senior author Kimmie Ng, MD, MPH, director of the Young-Onset Colorectal Cancer Center at Dana-Farber. “This is the first study to compare survival in younger versus older patients participating in a clinical trial of treatment for metastatic colorectal cancer.”
The study drew on clinical trial data which tested a combination of chemotherapy and biologic therapy in patients with metastatic colorectal cancer, comparing patients under 50 with those over 50.
“We found no significant difference in overall survival between the two groups,” said Dana-Farber’s Marla Lipsyc-Sharf, MD, the first author of the study. 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, 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 noted, but it aligns with previous research suggesting that very young patients have worse outcomes.
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. Yet despite a wellspring of new research, no definitive cause for the increase has been found.
“If current trends hold, colorectal cancer is projected to be the second leading cancer and leading cause of cancer death in patients ages 20–49 by the year 2040,” Lipsyc-Sharf stated. “It is important to understand survival in this population in order to develop tailored treatments.”
That younger patients fare no better than older ones despite more favourable factors could suggest that colorectal cancer is more aggressive at an earlier age. But there is no conclusive evidence that that is the case.
“Research has yet to identify consistent molecular differences in the colorectal cancer cells of younger patients and older patients,” Dr Lipsyc-Sharf noted. Current studies also are exploring whether differences in the intestinal microbiome of younger and older patients might explain the increased incidence of early-onset colorectal cancer.
Source: Dana Farber Cancer Institute
