Early-onset colorectal cancer in younger patients: A population-based study.

Abstract

124 Background: In the US, the incidence of colorectal cancer (CRC) is increasing in patients younger than 50 years who may present with advanced stage, high grade, left-sided colon or rectal cancers with signet ring cell histopathology, aggressive clinical course, and reduced overall survival. Understanding the characteristics of this population could inform screening, early detection, and optimal treatment. In this study, we describe the attributes of adults who are 50 years and younger with a first diagnosis of CRC and ascertain molecular testing rates and time to surgery by using data from a commercially insured cohort in the U.S. Methods: This retrospective study of patients ages 50 and younger with a first diagnosis of CRC utilizes the IBM MarketScan database, and focuses on claims from January 2013 to December 2018. Included patients had continuous insurance enrollment of 12 months before and 6 months after diagnosis. We determined rates of tumor testing for microsatellite instability (MSI) or immunohistochemistry (IHC) for mismatch repair (MMR) proteins and referral to genetic services in all patients, as well as mutational analysis of KRAS, NRAS, and BRAF in metastatic CRC patients. Time to surgical resection of primary tumor (TTS) in non-metastatic colon cancer patients was measured. Results: During the 5-year period, 10,577 patients ages 18 to 50 years had a first diagnosis of CRC, which was 15.6% of the 67,921 adults of all ages with CRC. Claims for MSI or IHC for MMR proteins within 120 days of initial diagnosis were done in 4,429 (41.9%) patients and referral to genetics services/counseling within 1 year of initial diagnosis were done in 443 (4.1%) patients. Among metastatic CRC patients, KRAS, NRAS, or BRAF tumor mutational analyses within 120 days of initial diagnosis were documented in 323 (31.5%). The median TTS ranged from 7 to 15 days with no statistically significant differences based on geographic region or health insurance plan type. Conclusions: Younger patients with early onset CRC had low rates of referral to genetics services, tumor MSI or IHC for MMR proteins testing, and KRAS, NRAS, and BRAF mutational analysis. There were no geographic or insurance type trends in TTS in non-metastatic colon cancer patients. Although underreporting is possible in our study, the findings of low utilization of genetic services and tumor genomic testing in these younger patients with early onset CRC should alert the oncology community to critical management gaps in the care of this population.