Patients with Early-Onset Colorectal Cancer Have an Increased Risk of Second Primary Malignancy

Area of Science:

• Oncology
• Epidemiology
• Cancer Research

Background:

• Colorectal cancer (CRC) incidence is decreasing overall in the USA.
• Early-onset CRC (eoCRC) incidence in individuals under 50 is increasing.
• The risk of second primary malignancy (SPM) in eoCRC patients is not well understood.

Purpose of the Study:

• To investigate the risk of SPM in patients with eoCRC.
• To compare the SPM risk in eoCRC patients versus late-onset CRC (loCRC) patients.
• To identify specific cancer types and risk factors associated with SPM after eoCRC.

Main Methods:

• Utilized data from the Surveillance, Epidemiology, and End Results (SEER) Program database.
• Calculated Standardized Incidence Ratios (SIR) to compare SPM risk in eoCRC and loCRC patients to the general population.
• Analyzed SPM risk based on time since diagnosis, sex, race, income, and birth cohort.

Main Results:

• Individuals with eoCRC showed a 42% increased lifetime risk of SPM (SIR 1.42), unlike loCRC patients (SIR 1.00).
• Highest SPM risks were observed for small intestine, ureter, rectum, and colon cancers.
• SPM risk was higher in non-whites, those with lower income, and peaked within the first 5 years post-diagnosis (SIR 2.44).

Conclusions:

• Patients with eoCRC have a nearly 50% higher lifetime risk of developing SPM compared to the general population.
• The risk of SPM after eoCRC is elevated in the initial five years post-diagnosis.
• The incidence of SPM following eoCRC is increasing over time, indicating a growing public health concern.