The histological and molecular characteristics of early-onset colorectal cancer: a systematic review and meta-analysis.

Background: Early-onset colorectal cancer (CRC), defined as diagnosis before age 50, has increased in recent decades. Although more often diagnosed at advanced stage, associations with other histological and molecular markers that impact prognosis and treatment remain to be clarified. We conducted a systematic review and meta-analysis concerning the prevalence of prognostic and predictive tumor markers for early- vs. late-onset CRC, including oncogene mutations, microsatellite instability (MSI), and emerging markers including immune cells and the consensus molecular subtypes. Methods: We systematically searched PubMed for original research articles published between April 2013-January 2024. Included studies compared the prevalence of tumor markers in early- vs. late-onset CRC. A meta-analysis was completed and summary odds ratios (ORs) with 95% confidence intervals (CIs) were obtained from a random effects model via inverse variance weighting. A sensitivity analysis was completed to restrict the meta-analysis to studies that excluded individuals with Lynch syndrome, a hereditary condition that influences the distribution of tumor markers for early-onset CRC. Results: In total, 149 articles were identified. Tumors from early-onset CRC are less likely to include mutations in KRAS (OR, 95% CI: 0.91, 0.85-0.98), BRAF (0.63, 0.51-0.78), APC (0.70, 0.58-0.84), and NRAS (0.88, 0.78-1.00) but more likely to include mutations in PTEN (1.68, 1.04-2.73) and TP53 (1.34, 1.24-1.45). After limiting to studies that excluded Lynch syndrome, the associations between early-onset CRC and BRAF (0.77, 0.64-0.92) and APC mutation (0.81, 0.67-0.97) were attenuated, while an inverse association with PIK3CA mutation was also observed (0.88, 0.78-0.99). Early-onset tumors are less likely to develop along the CpG Island Methylator Phenotype pathway (0.24, 0.10-0.57), but more likely to possess adverse histological features including high tumor grade (1.20, 1.15-1.25), and mucinous (1.22, 1.16-1.27) or signet ring histology (2.32, 2.08-2.57). A positive association with MSI status (1.31, 1.11-1.56) was also identified. Associations with immune markers and the consensus molecular subtypes are inconsistent. Discussion: A lower prevalence of mutations in KRAS and BRAF is consistent with extended survival and superior response to targeted therapies for metastatic disease. Conversely, early-onset CRC is associated with aggressive histological subtypes and TP53 and PTEN mutations, which may serve as therapeutic targets.

Racial disparities in colorectal cancer clinicopathological and molecular tumor characteristics: a systematic review.

PURPOSE: African Americans have the highest colorectal cancer (CRC) mortality of all racial groups in the USA, which may relate to differences in healthcare access or advanced stage at diagnosis. Recent evidence indicates that differences in tumor characteristics may also underlie disparities in mortality. To highlight recent findings and areas for investigation, we completed the first systematic review of racial disparities in CRC tumor prognostic markers, including clinicopathological markers, microsatellite instability (MSI), oncogene mutations, and novel markers, including cancer stem cells and immune markers. METHODS: Relevant studies were identified via PubMed, limited to original research published within the last 10 years. Ninety-six articles were identified that compared the prevalence of mortality-related CRC tumor characteristics in African Americans (or other African ancestry populations) to White cases. RESULTS: Tumors from African ancestry cases are approximately 10% more likely to contain mutations in KRAS, which confer elevated mortality and resistance to epidermal growth factor receptor inhibition. Conversely, African Americans have approximately 50% lower odds for BRAF-mutant tumors, which occur less frequently but have similar effects on mortality and therapeutic resistance. There is less consistent evidence supporting disparities in mutations for other oncogenes, including PIK3CA, TP53, APC, NRAS, HER2, and PTEN, although higher rates of PIK3CA mutations and lower prevalence of MSI status for African ancestry cases are supported by recent evidence. Although emerging evidence suggests that immune markers reflecting anti-tumor immunity in the tumor microenvironment may be lower for African American cases, there is insufficient evidence to evaluate disparities in other novel markers, cancer stem cells, microRNAs, and the consensus molecular subtypes. CONCLUSION: Higher rates of KRAS-mutant tumors in in African Americans may contribute to disparities in CRC mortality. Additional work is required to understand whether emerging markers, including immune cells, underlie the elevated CRC mortality observed for African Americans.

Associations of Albumin and BMI with Colorectal Cancer Risk in the Southern Community Cohort Study: a Prospective Cohort Study.

BACKGROUND: Obesity may increase colorectal cancer (CRC) risk through mechanisms of increased inflammation. Although BMI is the most used adiposity indicator, it may less accurately measure adiposity in Black populations. Herein, we investigate associations between BMI, low albumin as an inflammation biomarker, and CRC risk in a racially diverse cohort. METHODS: Participant data arise from 71,141 participants of the Southern Community Cohort Study, including 724 incident CRC cases. Within the cohort, 69% are Black. Blood serum albumin concentrations, from samples taken at enrollment, were available for 235 cases and 567 controls. Controls matched by age, sex, and race were selected through incidence density sampling. Cox proportional hazards calculated BMI and CRC risk associations (hazard ratios [HRs]; 95% confidence intervals [CIs]. Conditional logistic regression calculated albumin and CRC risk associations (odds ratios [ORs]; 95%CIs). RESULTS: Underweight, but not overweight or obese, compared to normal BMI was associated with increased CRC risk (HR:1.75, 95%CI:1.00-3.09). Each standard deviation increase of albumin was associated with decreased CRC risk, particularly for those who self-identified as non-Hispanic Black (OR: 0.56, 95%CI:0.34-0.91), or female (OR:0.54, 95%CI:0.30-0.98), but there was no evidence for interaction by these variables (p-interactions > 0.05). Moreover, albumin concentration was lower in Black than White participants. Mediation analysis suggested that the relation between albumin and CRC was not mediated by BMI. CONCLUSIONS: Null associations of overweight/obesity with CRC risk demonstrates limited utility of BMI, especially among Black populations. Low albumin may indicate CRC risk. In Black individuals, albumin may better predict adiposity related risks than BMI.

Genome-wide association study (GWAS) of circulating vitamin D outcomes among individuals of African ancestry.

BACKGROUND: Vitamin D deficiency is more common among African-ancestry individuals and may be associated with adverse health outcomes. Vitamin D binding protein (VDBP) regulates concentrations of biologically active vitamin D. OBJECTIVE: We conducted genome-wide association study (GWAS) of VDBP and 25-hydroxyvitamin D among African-ancestry individuals. METHODS: Data were collected from 2,602 African American adults from the Southern Community Cohort Study (SCCS) and 6,934 African- or Caribbean-ancestry adults from the UK Biobank. Serum VDBP concentrations were available only in the SCCS and were measured by using the Polyclonal Human VDBP ELISA kit. Serum 25-hydroxyvitamin D concentrations for both study samples were measured by using Diasorin Liason, a chemiluminescent immunoassay. Participants were genotyped for single nucleotide polymorphisms (SNPs) with genome-wide coverage by using Illumina or Affymetrix platforms. Fine-mapping analysis was performed by using forward stepwise linear regression models including all variants with P value < 5 × 10-8 and within 250 kbps of a lead SNP. RESULTS: We identified 4 loci notably associated with VDBP concentrations in the SCCS population: rs7041 (per allele ß = 0.61 µg/mL, SE = 0.05, P = 1.4 × 10-48) and rs842998 (per allele ß = 0.39 µg/mL, SE = 0.03, P = 4.0 × 10-31) in GC, rs8427873 (per allele ß = 0.31 µg/mL, SE = 0.04, P = 3.0 × 10-14) near GC and rs11731496 (per allele ß = 0.21 µg/mL, SE = 0.03, P = 3.6 × 10-11) in between GC and NPFFR2. In conditional analyses, which included the above-mentioned SNPs, only rs7041 remained notable (P = 4.1 × 10-21). SNP rs4588 in GC was the only GWAS-identified SNP associated with 25-hydroxyvitamin D concentration. Among UK Biobank participants: per allele ß = -0.11 µg/mL, SE = 0.01, P = 1.5 × 10-13; in the SCCS: per allele ß = -0.12 µg/mL, SE = 0.06, P = 2.8 × 10-02). rs7041 and rs4588 are functional SNPs that influence the binding affinity of VDBP to 25-hydroxyvitamin D. CONCLUSIONS: Our results were in line with previous studies conducted in European-ancestry populations, showing that GC, the gene that directly encodes for VDBP, would be important for VDBP and 25-hydroxyvitamin D concentrations. The current study extends our knowledge of the genetics of vitamin D in diverse populations.