PIK3CA Somatic Mutation Status in Relation to Patient and Tumor Factors in Racial/Ethnic Minorities with Colorectal Cancer.

Abstract

BACKGROUND:

Approximately 10% to 20% of colorectal cancers exhibit somatic mutations in the phosphoinositide-3-kinase, catalytic, alpha polypeptide gene (PIK3CA). We evaluated the relationship of PIK3CA mutation status in colorectal cancer with race/ethnicity, colorectal cancer survival, and other patient and tumor factors.

METHODS:

This study comprised 377 racial/ethnic minorities with incident invasive colorectal cancer, enrolled in the Colon Cancer Family Registry via population-based cancer registries. Tumor specimens were tested for PIK3CA mutations in exon 9 and 20 hotspots, BRAF p.V600E mutations, and DNA mismatch repair (MMR). In logistic regression models, we evaluated the association between PIK3CA mutation status and race/ethnicity, overall, and by mutation site. Using Cox regression, we evaluated the association between PIK3CA mutation status and survival after colorectal cancer diagnosis.

RESULTS:

PIK3CA mutations were detected in 42 cases (11%), with a similar prevalence across racial/ethnic groups. Individuals with PIK3CA-mutated colorectal cancer were significantly more likely than those with PIK3CA-wildtype disease to have proximal colon cancer, MMR-deficient tumors, and a germline MMR mutation (P ≤ 0.01). There was no evidence for an association between PIK3CA and overall survival (HR, 0.77; 95% confidence interval, 0.43-1.39).

CONCLUSIONS:

The prevalence of PIK3CA mutation status in colorectal cancer does not differ according to race/ethnicity, but may vary according to other relevant clinicopathologic and etiologic factors, including germline MMR mutation status, tumor MMR status, and tumor site.

IMPACT:

These findings underscore the importance of PIK3CA mutation status in colorectal cancer epidemiology and provide evidence that the prevalence of such mutations is similar across several racial/ethnic groups.

• Authors: Amanda I Phipps, Dennis J Ahnen, Iona Cheng, Polly A Newcomb, Aung Ko Win, Terrilea Burnett
• Journal: Cancer epidemiology, biomarkers & prevention : a publication of the American Association for Cancer Research, cosponsored by the American Society of Preventive Oncology (Cancer Epidemiol Biomarkers Prev) Vol. 24 Issue 7 Pg. 1046-51 (Jul 2015) ISSN: 1538-7755 [Electronic] United States
• PMID: 25994739 (Publication Type: Journal Article, Multicenter Study, Research Support, N.I.H., Extramural)
• Copyright: ©2015 American Association for Cancer Research.

Chemical References

• Biomarkers, Tumor
• DNA, Neoplasm
• Phosphatidylinositol 3-Kinases
• Class I Phosphatidylinositol 3-Kinases
• PIK3CA protein, human

Topics

• Adult
• Aged
• Aged, 80 and over
• Biomarkers, Tumor (genetics)
• Class I Phosphatidylinositol 3-Kinases
• Colorectal Neoplasms (diagnosis, ethnology, genetics)
• DNA Mutational Analysis
• DNA, Neoplasm (genetics)
• Female
• Global Health
• Humans
• Incidence
• Male
• Middle Aged
• Minority Groups
• Mutation
• Neoplasm Staging
• Phosphatidylinositol 3-Kinases (genetics, metabolism)
• SEER Program
• United States (epidemiology)
• Young Adult