Clinical Multigene Panel Testing Identifies Racial and Ethnic Differences in Germline Pathogenic Variants Among Patients With Early-Onset Colorectal Cancer

Genomic ancestry and cancer among Latin Americans

Latin American populations, characterized by intricate admixture patterns resulting from the intermingling of ancestries from European, Native American (NA) Asian, and African ancestries which result in a vast and complex genetic landscape, harboring unique combinations of novel variants. This genetic diversity not only poses challenges in traditional population genetics methods but also opens avenues for a deeper understanding of its implications in health. In cancer, the interplay between genetic ancestry, lifestyle factors, and healthcare disparities adds a layer of complexity to the varying incidence and mortality rates observed across different Latin American subpopulations. This complex interdependence has been unveiled through numerous studies, whether conducted on Latin American patients residing on the continent or abroad, revealing discernible differences in germline composition that influence divergent disease phenotypes such as higher incidence of Luminal B and Her2 breast tumors, EGFR and KRAS mutated lung adenocarcinomas in addition to an enrichment in BRCA1/2 pathogenic variants and a higher than expected prevalence of variants in colorectal cancer associated genes such as APC and MLH1. In prostate cancer novel risk variants have also been solely identified in Latin American populations. Due to the complexity of genetic divergence, inputs from each individual ancestry seem to carry independent contributions that interplay in the development of these complex disease phenotypes. By understanding these unique population characteristics, genomic ancestries hold a promising avenue for tailoring prognostic assessments and optimizing responses to oncological interventions.

Impact of tumor size on overall survival and cancer-specific survival of early-onset colon and rectal cancer: a retrospective cohort study

PURPOSE

This study aimed to investigate the impact of tumor size on survival in early-onset colon and rectal cancer.

METHODS

Early-onset colon and rectal cancer patients were identified from the Surveillance, Epidemiology, and End Results (SEER) database between 2004 and 2015. Tumor size was analyzed as both continuous and categorical variables. Several statistical techniques, including restricted cubic spline (RCS), Cox proportional hazard model, subgroup analysis, propensity score matching (PSM), and Kaplan-Meier survival analysis, were employed to demonstrate the association between tumor size and overall survival (OS) and cancer-specific survival (CSS) of early-onset colon and rectal cancer.

RESULTS

Seventeen thousand five hundred fifty-one (76.7%) early-onset colon and 5323 (23.3%) rectal cancer patients were included. RCS analysis confirmed a linear association between tumor size and survival. Patients with a tumor size > 5 cm had worse OS and CSS, compared to those with a tumor size ≤ 5 cm for both early-onset colon and rectal cancer. Notably, subgroup analysis showed that a smaller tumor size (≤ 50 mm) was associated with worse survival in stage II early-onset colon cancer, although not statistically significant. After PSM, Kaplan-Meier survival curves showed that the survival of patients with tumor size ≤ 50 mm was better than that of patients with tumor size > 50 mm.

CONCLUSION

Patients with tumors larger than 5 cm were associated with worse survival in early-onset colon and rectal cancer. However, smaller tumor size may indicate a more biologically aggressive phenotype, correlating with poorer survival in stage II early-onset colon cancer.

Racial Disparities in Receipt of Guideline-Concordant Care for Early-Onset Colorectal Cancer in the United States

PURPOSE

Young individuals racialized as Black are more likely to die after a colorectal cancer (CRC) diagnosis than individuals racialized as White in the United States. This study examined racial disparities in receipt of timely and guideline-concordant care among individuals racialized as Black and White with early-onset CRC.

METHODS

Individuals age 18-49 years racialized as non-Hispanic Black and White (self-identified) and newly diagnosed with CRC during 2004-2019 were selected from the National Cancer Database. Patients who received recommended care (staging, surgery, lymph node evaluation, chemotherapy, and radiotherapy) were considered to have received guideline-concordant care. Odds ratios (ORs) were adjusted for age and sex. The decomposition method was used to estimate the relative contribution of demographic characteristics (age and sex), comorbidities, health insurance, and facility type to the racial disparity in receipt of guideline-concordant care. The product-limit method was used to evaluate differences in time to treatment between patients racialized as Black and White.

RESULTS

Of the 84,882 patients with colon cancer and 62,573 patients with rectal cancer, 20.8% and 14.5% were racialized as Black, respectively. Individuals racialized as Black were more likely to not receive guideline-concordant care for colon (adjusted OR [aOR], 1.18 [95% CI, 1.14 to 1.22]) and rectal (aOR, 1.27 [95% CI, 1.21 to 1.33]) cancers. Health insurance explained 28.2% and 21.6% of the disparity among patients with colon and rectal cancer, respectively. Individuals racialized as Black had increased time to adjuvant chemotherapy for colon cancer (hazard ratio [HR], 1.28 [95% CI, 1.24 to 1.32]) and neoadjuvant chemoradiation for rectal cancer (HR, 1.42 [95% CI, 1.37 to 1.47]) compared with individuals racialized as White.

CONCLUSION

Patients with early-onset CRC racialized as Black receive worse and less timely care than individuals racialized as White. Health insurance, a modifiable factor, was the largest contributor to racial disparities in receipt of guideline-concordant care in this study.

Temporal trends in early-onset colorectal cancer incidence (2000-2020) by age group and five geographic regions in the state of Georgia

The increase of early-onset colorectal cancer (CRC) among younger adults is a major public health concern. However, little is known about variations in CRC incidence across different age groups within small geographic areas in Georgia. We examined temporal trends of CRC incidence in Clayton, East Central, West Central, Northeast, and Southeast regions, by age groups. Annual incidence rates for CRC in individuals aged 15+ years during 2000-2020 in the five regions of Georgia were included. Temporal trends were examined within the five regions and stratified by age group. Joinpoint regression was employed to calculate the annual percent change and corresponding 95% confidence intervals (CIs). Among 20,215 CRC diagnoses, CRC incidence declined over time for East Central (-2.33%; 95% CI, -3.03, -1.64), Northeast (-1.63%; 95% CI, -2.15, -1.04), Southeast (-1.63%; 95% CI, -2.30, -0.96), and West Central (-1.53%; 95% CI, -2.04, -1.03) Georgia. In the 15-44 age group, a notable increase of CRC incidence was found in Clayton, Northeast, and Southeast regions with a range of 2.2%-3.4%. However, adults aged 60+ years experienced a significant decrease in CRC incidence for most Georgia regions (all p-value <0.05), except for the Clayton region. In conclusion, CRC incidence declined during 2000-2020 in most Georgia regions. However, early-onset CRC is a major concern in Georgia as young adults (<45 years) living in Clayton, Northeast, and Southeast Georgia experienced significant annual increases in CRC incidence. Targeted CRC screening and awareness campaigns should be prioritized for adults <45 years and in the most impacted areas in Georgia.