What you carry at this position in your DNA and what research says about it.
Cancer Risk: 10/10 evidence, 75 publications.
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Sample genotype (not yours): G/G
Higher Risk of Prostate and Colorectal Cancers
Inheriting two copies of the G allele is associated with a significantly higher risk of developing prostate and colorectal cancers. This genetic profile also means that standard preventive aspirin therapy may not provide the same protective colon benefits seen in other genotypes.
What this genotype means: Significantly increased risk of prostate and colorectal cancers; Reduced preventative benefit from regular aspirin use; Higher baseline prostate-specific antigen levels.
Sample genotype (not yours): G/T
Moderately Higher Colorectal Cancer Risk
Inheriting one G and one T allele is linked to a moderate increase in the risk of developing colorectal cancer. This region regulates MYC, a gene involved in cell growth.
What this genotype means: Moderately increased risk of prostate and colorectal cancers; Retained preventative benefit from regular aspirin use; Slightly elevated baseline prostate-specific antigen levels.
Sample genotype (not yours): T/T
Typical Cancer Risk and Enhanced Aspirin Benefit
Inheriting two copies of the T allele is associated with a typical, baseline risk for prostate and colorectal cancers. Regular aspirin use is highly effective at further reducing the risk of developing colorectal tumors for this genotype.
What this genotype means: Typical baseline risk for prostate and colorectal cancers; Strong preventative benefit from regular aspirin use; Typical baseline prostate-specific antigen levels.
Gene function and biological role
Gene Function: The CASC8 gene is located on chromosome 8q24, a region highly associated with cancer development. This gene produces a long non-coding RNA that acts as a regulatory element rather than encoding a protein. It overlaps with other key non-coding transcripts like CCAT2 [1]. CASC8 and CCAT2 function as enhancers that regulate the expression of the MYC oncogene, a powerful driver of cell growth and division [2]. Alterations in this genomic region can disrupt normal cellular regulation, leading to chromosomal instability and tumor progression [1].
Variant Impact: The rs6983267 variant is an intron variant located within the CASC8 gene and the overlapping CCAT2 transcript [1]. This single nucleotide change alters a transcription factor binding site, directly affecting how efficiently the enhancer interacts with the MYC promoter [2]. The G allele increases the transcription of CCAT2 and enhances MYC expression, promoting tumor growth and cellular proliferation [3]. Conversely, the T allele is associated with lower enhancer activity and reduced cancer risk [4]. This variant is one of the most thoroughly researched genetic risk factors for prostate and colorectal cancers [5].
Key Insight: The G allele of this variant acts as a physical booster for the MYC oncogene, directly driving tumor growth, whereas mice lacking this enhancer region are highly resistant to intestinal tumors.
Location: CASC8. Chromosome 8 · 8q24.21 · 127.4 Mb
Estimated prevalence by population
Global 41.3%; European 26.0%; African 80.2%; East Asian 15.9%; South Asian 25.5%; Americas 31.1%; Ashkenazi 24.4%; Finnish 27.7%; Middle Eastern 36.7%; Amish 40.6%.
Estimated GG genotype frequency.
Global 41.2%; European 50.0%; African 18.7%; East Asian 47.9%; South Asian 50.0%; Americas 49.3%; Ashkenazi 50.0%; Finnish 49.9%; Middle Eastern 47.8%; Amish 46.2%.
Estimated GT genotype frequency.
Global 17.5%; European 24.1%; African 1.1%; East Asian 36.2%; South Asian 24.5%; Americas 19.6%; Ashkenazi 25.6%; Finnish 22.4%; Middle Eastern 15.6%; Amish 13.1%.
Estimated TT genotype frequency.
Showing effects for G/G genotype
Cancer & Oncology
Colorectal Cancer
Colorectal Cancer. Evidence: 10/10. Source: PMID 17618284. ~1.68x Risk.
Colon Polyps. Evidence: 8/10. Source: PMID 34594039. Increased Risk.
Prostate Cancer
Prostate Cancer. Evidence: 10/10. Source: PMID 17401363. ~1.6x Risk.
PSA Levels. Evidence: 10/10. Source: PMID 37264206. Elevated Levels.
Pharmacogenomics
Adverse Drug Reactions
Aspirin Benefit. Evidence: 3/10. Source: PMID 29425227. No Benefit.
Showing effects for G/T genotype
Colorectal Cancer. Evidence: 10/10. Source: PMID 17618284. ~1.39x Risk.
Colon Polyps. Evidence: 8/10. Source: PMID 34594039. Slightly Increased.
Prostate Cancer. Evidence: 10/10. Source: PMID 17401363. ~1.3x Risk.
PSA Levels. Evidence: 10/10. Source: PMID 37264206. Slightly Elevated.
Aspirin Benefit. Evidence: 3/10. Source: PMID 29425227. Reduced Cancer Risk.
Showing effects for T/T genotype
Colorectal Cancer. Evidence: 10/10. Source: PMID 17618284. Typical Risk.
Colon Polyps. Evidence: 8/10. Source: PMID 34594039. Typical Risk.
Prostate Cancer. Evidence: 10/10. Source: PMID 17401363. Typical Risk.
PSA Levels. Evidence: 10/10. Source: PMID 37264206. Typical Levels.
Aspirin Benefit. Evidence: 3/10. Source: PMID 29425227. Strongly Reduced Risk.
What this genotype means for the people who carry it
Sample genotype: GG (Homozygous)
Carrying the G/G genotype leads to increased activity of a genetic enhancer that drives the expression of the MYC oncogene, a major promoter of cell division and tumor growth [1]. Multiple large-scale genome-wide association studies have confirmed that this genotype is linked to an approximately 1.6-fold increase in prostate cancer risk [2]. It is also associated with a 1.68-fold increased risk of colorectal cancer and a higher likelihood of developing colon polyps. Furthermore, clinical research indicates that regular aspirin use does not lower colorectal cancer risk for those with this specific genetic profile [3]. In addition, this genotype is associated with higher baseline levels of prostate-specific antigen (PSA), which can complicate prostate cancer screening interpretation [4]. Understanding these risks highlights the importance of discussing early cancer screening strategies with a healthcare provider.
Significantly increased risk of prostate and colorectal cancers; Reduced preventative benefit from regular aspirin use; Higher baseline prostate-specific antigen levels.
Sample genotype: GT (Heterozygous)
Having one copy of the risk-associated G allele moderately elevates the expression of the MYC oncogene, leading to intermediate cancer susceptibility [1]. Large clinical cohorts show that this genotype carries an approximately 1.3-fold increased risk for prostate cancer and a 1.39-fold increased risk for colorectal cancer. It is also associated with a higher rate of benign colon polyps and adenomas [2]. However, unlike the G/G genotype, those with the G/T genotype show a positive response to preventive aspirin therapy, which can significantly reduce colorectal cancer incidence [3]. This genotype is also associated with slightly elevated prostate-specific antigen (PSA) levels [4]. Proactive lifestyle choices and personalized screening schedules are highly effective tools for managing these inherited risks.
Moderately increased risk of prostate and colorectal cancers; Retained preventative benefit from regular aspirin use; Slightly elevated baseline prostate-specific antigen levels.
Sample genotype: TT (Homozygous)
Possessing the T/T genotype represents the baseline genetic profile, avoiding the elevated cancer risks associated with the G allele [1]. Studies show that this genotype is linked to typical rates of prostate and colorectal cancers, as well as a normal likelihood of developing colon polyps. Furthermore, clinical trials have demonstrated that regular aspirin use is exceptionally beneficial for those with this genotype, reducing colorectal cancer risk by up to 31% [2]. This protective effect of aspirin appears to be highly specific to T allele carriers [3]. Baseline prostate-specific antigen (PSA) levels also tend to be typical, making standard screening guidelines highly reliable [4]. Maintaining routine health checkups and a healthy lifestyle remains the best approach to long-term wellness.
Typical baseline risk for prostate and colorectal cancers; Strong preventative benefit from regular aspirin use; Typical baseline prostate-specific antigen levels.
Variants with shared genetic architecture
rs10505477 · CASC8 Gene · Chr 8 · Cancer Susceptibility Risk
rs13281615 · CASC8 Gene · Chr 8 · Breast Cancer Risk
rs1447295 · CASC8 Gene · Chr 8 · Prostate Cancer Risk
Mice lacking a Myc enhancer that includes human SNP rs6983267 are resistant to intestinal tumors.
Genome-wide association study of prostate cancer identifies a second risk locus at 8q24.
Discovery of common and rare genetic risk variants for colorectal cancer.
Content updated August 2026.
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