By Megan Brooks
Source: Reuters - 22/7/2019
More people in the US are developing colorectal cancer before age 50, a trend that has also been seen in Europe.
This study "confirms that colorectal cancer is an increasing problem among adults younger than 50 years, and this should be considered in the ongoing debate over the age at which to begin screening," the study team, from The University of Texas at Austin, concludes in a paper online today in Cancer.
Dr. Boone Goodgame and colleagues analyzed data from the National Cancer Database registry, which includes more than 70% of new cancer cases in the U.S. From 2004 to 2015, 130,165 patients under age 50 and 1,055,598 patients over age 50 were diagnosed with colorectal cancer.
The proportion of patients with colorectal cancer diagnosed before age 50 rose significantly, from 10% in 2004 to 12.2% in 2015 (P<0.001), the investigators report. Younger adults were also more likely to be diagnosed with more advanced stages of colorectal cancer (stage III/IV: 52% vs 40% of those diagnosed after age 50).
The proportion of young-onset CRC was higher in African American (13.9%) and Hispanic populations (18.9%) than non-Hispanic whites.
Rates of CRC diagnosis before age 50 increased throughout the study period regardless of income level. The highest proportion of young adult diagnoses occurred in the top income category, the researchers found. The proportion of CRC cases diagnosed in younger people rose in urban areas, but not in rural areas.
"It is clear from our study and previous studies that the age at diagnosis of CRC is dropping," write Dr. Goodgame and colleagues. And while the causes are unclear, some data suggest the rising proportion of CRC cases seen in young adults may be due to "access to health care resources (primarily screening) as well as lifestyle factors such as obesity and meat consumption," they note.
In email to Reuters Health, Dr. Goodgame said CRC screening guidelines are "currently being debated. For example, the American Cancer Society now recommends screening at age 45 and the US Preventive Services Task Force (USPSTF) recommends screening at age 50. However, most people don't adhere to either current guideline, so the most important first step is to encourage people not to delay screening after age 50."
Writing in an editorial published with the study, Dr. Chyke Doubeni from the University of Pennsylvania, points to the need for additional research.
"The uptake of screening has increased over time in the United States, and this is considered the main con- contributor to the decreasing incidence and mortality rates in the United States. The screening initiation age is not an exact science, and screening occurs in people younger than 50 years," he writes.
"Because the number of colorectal cancer cases from inherited causes are much higher in younger individuals, it is unknown whether screening for sporadic cases in a group with such low disease rate can result in a favorable balance of harms and benefits," Dr. Doubeni says.
"It is therefore imperative that the various hypotheses for increasing colorectal cancer incidence among people younger than 50 be rigorously tested to determine if changing the current screening age in people who are not at increased familial risk represents the most appropriate public health response," Dr. Doubeni concludes.
Support for the study was provided by the National Cancer Institute and the Cancer Prevention and Research Institute of Texas. The authors have declared no conflicts of interest.