Early onset colorectal cancers are increasing in incidence. Studies have reported a left-sided preponderance of cancers in patients <50 years, leading some to advocate for screening with flexible sigmoidoscopy at age 40.

The purpose of our study was to investigate tumor characteristics and patient outcomes in sporadic right- and left-sided early onset colorectal cancers.

This was a retrospective cohort study.

This study was conducted at a single, tertiary care institution.

Patients <50 years diagnosed with colorectal cancer between 2000 and 2018.

We analyzed patient demographics, tumor characteristics, overall survival, and disease-free survival.

A total of 489 patients aged 20-49 were identified from 2000-2018. The majority of patients were white (90%) and male (57%). The median age at diagnosis was 44 years and 75% were diagnosed between 40-49 years. There was a predominance of left-sided tumors (80%). The majority of patients presented with stage 3 (35%) and stage 4 (35%) disease. Right-sided tumors were more likely to have mucinous (24% vs 7.4%, P<0.001) and signet-ring cell (4.4% vs 1.7%, p < 0.001) histology. There was no difference in age, sex, race, ethnicity, AJCC stage at presentation. Right-sided tumors were associated with lower 5-year overall survival (44% vs 61%, p < 0.005) with the decrease in survival most prominent in right-sided stage 3 tumors (41% vs 72%, p < 0.0001) and in ages 40-49 (43% vs 61%, p = 0.03). Sex, tumor location, increasing AJCC stage, and signet-ring cell histology were independent prognostic factors of overall survival. There was no significant difference in disease-free survival.

This study was a retrospective review at single institution.

The majority of early onset colorectal cancers arise during age 40-49 with a left-sided predominance but higher mortality in right-sided tumors. These findings provide further evidence in favor of recommending earlier initial screening colonoscopy for colorectal cancer. See Video Abstract at http://links.lww.com/DCR/B892.