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IMPORTANCE Early-onset colorectal cancer incidence rates among patients aged 45 to 49 years have been considered much lower compared with the rates among patients aged 50 to 54 years, prompting debate about earlier screening benefits at 45 years. However, the observed incidence rates in the Surveillance, Epidemiology, and End Results (SEER) registries may underestimate colorectal cancer case burdens in those younger than 50 years compared with those older than 50 years because average-risk screening is generally not performed to detect preclinical cases of colorectal cancer. Finding steep incidence increases of invasive stage (beyond in situ) cases of colorectal cancer from age 49 to 50 years would be consistent with high rates of preexisting, undetected cancers in younger patients ultimately receiving a diagnosis of colorectal cancer after undergoing screening at 50 years.OBJECTIVE To assess the preclinical burden of colorectal cancer by analyzing its incidence in 1-year age increments, focusing on the transition between ages 49 and 50 years. DESIGN, SETTING, AND PARTICIPANTSData from the SEER 18 registries, representing 28% of the US population, were used to conduct a cross-sectional study of colorectal cancer incidence rates from January 1, 2000, to December 31, 2015, in 1-year age increments (ages 30-60 years) stratified by US region (South, West, Northeast, and Midwest), sex, race, disease stage, and tumor location. Statistical analysis was conducted from November 1, 2018, to December 15, 2019. MAIN OUTCOMES AND MEASURES Incidence rates of colorectal cancer. RESULTS A total of 170 434 cases of colorectal cancer were analyzed among 165 160 patients (92 247 men [55.9%]; mean [SD] age, 51.6 [6.7] years). Steep increases in the incidence of colorectal cancer in the SEER 18 registries were found from 49 to 50 years of age (46.1% increase: 34.9 [95% CI, 34.1-35.8] to 51.0 [95% CI, 50.0-52.1] per 100 000 population). Steep rate increases from 49 to 50 years of age were also seen in all US regions, men and women, white and black populations, and in colon and rectal cancers. The rate ratio incidence increase in the SEER 18 registries from 49 to 50 years of age (1.46 [95% CI, 1.42-1.51]) was significantly higher than earlier 1-year age transitions. Steep rate increases in the SEER 18 registries were found from 49 to 50 years of age in localized-stage (75.9% increase: 11.2 [95% CI, 10.7-11.7] to 19.7 [95% CI, 19.0-20.3] per 100 000) and regional-stage (30.3% increase: 13.2 [95% CI, 12.7-13.8] to 17.2 [95% CI, 16.7-17.8] per 100 000) colorectal cancers. A total of 8799 of the 9474 cases (92.9%) of colorectal cancer in the SEER 18 registries from 2000 to 2015 that were diagnosed among individuals aged 50 years were invasive. CONCLUSIONS AND RELEVANCE Steep incidence increases between 49 and 50 years of age are consistent with previously undetected colorectal cancers diagnosed via screening uptake at 50 years. These cancers are not reflected in observed rates of colorectal cancer in the SEER registries among individuals y...

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mutations and tumor location have been associated with response to targeted therapy among patients with stage IV colorectal cancer (CRC) in various trials. This study performed the first population-based examination of associations between mutations, tumor location, and survival, and assessed factors associated with documented testing. Patients with stage IV adenocarcinoma of the colon/rectum diagnosed from 2010 to 2013 were extracted from SEER data. Analyses of patient characteristics, testing, and tumor location were conducted using logistic regression. Cox proportional hazards models assessed relationships between mutations, tumor location, and risk of all-cause death. Of 22,542 patients, 30% received testing, and 44% of these had mutations. Those tested tended to be younger, married, and metropolitan area residents, and have private insurance or Medicare. Rates of testing also varied by registry (range, 20%-46%). Patients with right-sided colon cancer (vs left-sided) tended to be older, female, and black; have mucinous, -mutant tumors; and have a greater risk of death (hazard ratio [HR], 1.27; 95% CI, 1.22-1.32). mutations were not associated with greater risk of death in the overall population; however, they were associated with greater risk of death among patients with left-sided colon cancer (HR, 1.19; 95% CI, 1.05-1.33). This large population-based study showed that among patients initially diagnosed with stage IV CRC, right-sided colon cancer was associated with greater risk of death compared with left-sided cancer, and mutations were only associated with risk of death in left-sided colon cancer. An unexpected finding was that among patients with stage IV disease, right-sided cancer was more commonly seen in black patients versus whites. Future studies should further explore these associations and determine the role of biology versus treatment differences. In addition, use of testing is increasing, but there is wide geographic variation wherein disparities related to insurance coverage and rurality may warrant further study.

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Background The Collaborative Stage (CS) Data Collection System enables multiple cancer registration programs to document anatomic and molecular pathology features that contribute to the Tumor (T), Node (N), Metastasis (M) (TNM) system of the American Joint Committee on Cancer (AJCC). This chapter highlights changes in CS for colon and rectal carcinomas as TNM moved from the AJCC 6th to the 7th edition. Methods Data from 18 Surveillance, Epidemiology, and End Results (SEER) population-based registries were analyzed for the years 2004-2010, which included 191 361colon and 73 341 rectal carcinomas. Results Overall, the incidence of colon and rectal cancer declined, with the greatest decrease in stage 0. The AJCC's 7th edition introduction of changes in the subcategorization of T4, N1, and N2 caused shifting within stage groups in 25 577 colon and 10 150 rectal cancers diagnosed in 2010. Several site-specific factors (SSFs) introduced in the 7th edition had interesting findings: 1) approximately 10% of colon and rectal cancers had tumor deposits - about 30-40% occurred without lymph node metastases which resulted in 2.5% of colon and 3.3% of rectal cases becoming N1c (stage III A/B) in AJCC 7th edition ; 2) 10% of colon and 12% of rectal cases had circumferential radial margins <1 mm; 3) about 46% of colorectal cases did not have a CEA testing or documented CEA information; and 4) about 10% of colorectal cases had perineural invasion. Conclusion Adoption of AJCC 7th edition by the SEER Program provides an assessment tool for staging and SSFs on clinical outcomes. This evidence can be used for education and improved treatment for colorectal carcinomas.

Despite frequently abnormal MSI/IHC results, LS screening in young, high-risk patients is low. Provider education and disparities in access to specialized services, particularly in underserved populations, are possible contributors. MSI/IHC results are infrequently available preoperatively.

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