Individuals diagnosed with primary colorectal cancer (CRC) at less than 50 years of age have better survival outcomes than individuals diagnosed at 51-55 years, based on data from more than 750,000 patients.
This finding emphasizes the importance of early CRC detection in younger individuals, reported lead author En Cheng, MD, PhD, of Yale University, New Haven, Conn., and colleagues.
“Early-onset CRC (i.e., CRC diagnosed at age less than 50 years) has been characterized by unique clinical, genetic, and epigenetic characteristics, and thus it may be associated with different survival from CRC diagnosed among individuals older than 50 years,” the investigators wrote in JAMA Network Open. Previous studies comparing survival times across age groups have yielded inconsistent results.
To gain a better understanding, the investigator conducted a retrospective study using data from the National Cancer Database. Excluding patients with primary CRC who had concomitant diagnosis, history of other malignant tumors, noninvasive adenocarcinoma, or missing data, the final dataset included 769,871 patients. Early-onset CRC was defined by age less than 50 years, whereas later-onset CRC was defined by ages 51-55 years.
“Individuals diagnosed at age 50 years were excluded to minimize an apparent screening detection bias at age 50 years in our population, given that these individuals disproportionately presented with earlier stages,” the investigators wrote.
Initial comparisons across groups revealed several significant differences. Individuals in the early-onset group were more often women (47.3% vs. 43.8%; P < .001), members of races in the “other” category (6.9% vs. 5.9%; P < .001), and Medicaid patients (12.3% vs. 10.3%; P < .001). They were also more likely to be diagnosed with stage IV cancer (27.8% vs 24.1%; P < .001) and have rectal tumors (29.3% vs. 28.7%; P = .004).
In the unadjusted Kaplan-Meier analysis, patients with early-onset CRC had a lower 10-year survival rate (53.6%; 95% CI, 53.2%-54.0% vs. 54.3%; 95% CI, 53.8%-54.8%; P < .001). The fully adjusted model revealed significantly higher survival for early-onset patients, compared with later-onset patients (adjusted hazard ratio, 0.95; 95% CI, 0.93-0.96; P < .001) . This disparity deepened when adjusting only for stage (HR, 0.89; 95% CI, 0.88-0.90; P < .001).
Survival was longest among patients 35-39 years (aHR, 0.88; 95% CI, 0.84-0.92; P < .001), compared with those aged 51-55, and among early-onset individuals with stage I disease (a HR, 0.87; 95% CI, 0.81-0.93; P < .001) or stage II disease (a HR, 0.86; 95% CI, 0.82-0.90; P < .001), compared with those having the same stages of later-onset CRC. No survival advantage was observed among patients diagnosed at age 25 or younger or those with stage III or IV disease.
“Interestingly, hereditary nonpolyposis colorectal cancer, owing to underlying mismatch repair deficiency, is associated with superior survival and is often diagnosed in individuals from ages 35-45 years,” the investigators noted. “In contrast, adenomatous polyposis coli syndrome is more common in individuals who are diagnosed with CRC at age younger than 20 years (10%), compared with those diagnosed at later ages (0.1%), and adenomatous polyposis coli syndrome is not associated with a survival advantage. These high penetrance syndromes could partly account for the relative heterogeneity in survival across ages among individuals with early-onset CRC.”