Colorectal cancer is the third most commonly diagnosed cancer and the second leading cause of cancer-related death in the United States. Colorectal cancer is most frequently diagnosed in people ages 65 to 74. US colorectal cancer incidence and mortality rates have decreased significantly since the 1970s, likely due to additional screening and treatment improvements. However, colorectal cancer incidence in people under 50 has increased by 1%-2% annually since the mid-1990s. By 2030, 10.9% of all colon cancers and 22.9% of all rectal cancers will affect patients younger than 50 (compared with 4.8% and 9.5%, respectively, in 2010).
Researchers have observed a similar increase in many other places around the world. Some evidence suggests westernized diets, high-fructose corn syrup, synthetic dyes, growth hormones used in food supply chains, obesity, and stress may lead to early-onset colorectal cancer. While earlier research suggested that early-onset colorectal cancer was inherently more aggressive, additional treatment for patients with such a disease has not improved survival.
Using an institutional database collected from patients at Memorial Sloan Kettering Cancer Center between 2014 and 2019, researchers here compared tumor biology in 759 patients with early-onset colorectal cancer compared with 687 patients diagnosed later. They investigated the location of the tumor, symptoms at diagnosis, patients' risks for hereditary colorectal cancer, and other tumor molecular features.
Patients with early-onset colorectal cancer were more likely to have tumors on the left side of their bodies. They were also more likely to experience rectal bleeding and abdominal pain. Patients with early-onset colorectal cancer also had a higher risk of inherited genetic predisposition for the disease. However, with regard to the genetic makeup of the tumors and response to treatment in advanced disease, the two types of patients were otherwise indistinguishable. This suggests that early-onset colorectal cancer is not biologically distinct from average-onset colorectal cancer and more aggressive treatment for early-onset colorectal cancer is neither necessary nor effective.
"The study noted no specific findings to differentiate early-onset colorectal cancer patients from average-onset colorectal cancer patients," said Cathy Eng of Vanderbilt-Ingram Cancer Center, who wrote an editorial to accompany the study. "I am hopeful with increased awareness and education, other investigators will collect additional data inclusive of a diverse patient population to determine if the findings from this study apply to the general public impacted by early-onset colorectal cancer."
The paper, "A comprehensive comparison of early-onset and average-onset colorectal cancers," will be available in the Journal of the National Cancer Institute today.