Study authors were somewhat surprised by the results because younger adults generally have fewer additional complicating health factors. “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,” said study senior author Kimmie Ng, MD, MPH, director of the Young-Onset Colorectal Cancer Center at Dana-Farber, in a statement. “They also tend to be treated with higher doses of therapy and have less severe side effects.” Dr. Ng and her colleagues compared survival times in 514 individuals who were younger than age 50 with the survival times of 1,812 patients above age 50. All had metastatic colorectal cancer and were participating in a clinical trial testing a combination of chemotherapy and biologic therapy. The scientists observed no significant difference in survival between the two groups. 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. The research team noted that results from those under age 35 were especially unexpected. Compared with any other age group, this population had the shortest median overall survival — 21.95 months. Because only a few subjects in the study were in this younger age group, study authors did not consider the result to be statistically significant. They added, however, that it corresponds with other investigations suggesting younger adults may have worse outcomes. “This could mean that the type of colorectal cancer younger patients have is more aggressive,” says Elena A. Ivanina, DO, MPH, director of neurogastroenterology and motility at Lenox Hill Hospital in New York City. While the overall incidence of colorectal cancer has been declining, the Dana-Farber Cancer Institute says that rates have been rising markedly in young people. Between 2000 and 2013, incidence of the disease in people under age 50 increased approximately 22 percent. If the trend holds, colorectal cancer could become the second leading cancer and leading cause of cancer death in patients ages 20 to 49 by the year 2040. Researchers are unsure what is fueling this unfortunate trend, but Dr. Ivanina suggests that several factors may be at play. “We know the major risk factors for adult-onset colorectal cancer, including obesity, physical inactivity, and smoking, but the risk factors for younger patients may be slightly different and involve the interrelated factors of diet, gut bacteria, and inflammation and the factors that influence them,” she says. Ivanina urges all adults — young and old — to take new gastrointestinal symptoms seriously. “Any time symptoms develop such as rectal bleeding or a change in stool they should be evaluated by a gastroenterologist no matter how young the patient may be,” she says. It’s also vital that adults get screened for colorectal cancer to catch it early on, when it is most treatable. The U.S. Preventive Services Task Force recommends that screenings for colorectal cancer begin at age 45.
