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Cohen SA, Turner EH, Beightol MB, Jacobson A, Gooley TA, Salipante SJ, Haraldsdottir S, Smith C, Scroggins S, Tait JF, Grady WM, Lin EH, Cohn DE, Goodfellow PJ, Arnold MW, de la Chapelle A, Pearlman R, Hampel H, Pritchard CC. Frequent PIK3CA Mutations in Colorectal and Endometrial Tumors With 2 or More Somatic Mutations in Mismatch Repair Genes. Gastroenterology 2016; 151:440-447.e1. [PMID: 27302833 PMCID: PMC5016834 DOI: 10.1053/j.gastro.2016.06.004] [Citation(s) in RCA: 32] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/13/2015] [Revised: 06/02/2016] [Accepted: 06/07/2016] [Indexed: 12/11/2022]
Abstract
BACKGROUND & AIMS Some colorectal and endometrial tumors with microsatellite instability not attributable to MLH1 hypermethylation or germline mutations contain 2 or more somatic mutations in genes encoding mismatch repair (MMR) proteins. We sought to define the molecular phenotype of this newly recognized tumor subtype. METHODS From 2 prospective studies of the efficacy of screening for Lynch syndrome, we identified patients with colorectal and endometrial tumors who had 2 or more somatic (but not germline) mutations in genes encoding MMR proteins (double somatic). We determined the frequencies of tumor mutations in PIK3CA, BRAF, KRAS, NRAS, and PTEN by targeted next-generation sequencing and used logistic-regression models to compare them with those from patients with Lynch syndrome, MLH1-hypermethylated, or microsatellite-stable tumors. We validated our findings using independent data sets from The Cancer Genome Atlas. RESULTS Among colorectal cancer cases, we found that 14 of 21 (67%) patients with double somatic tumors also had PIK3CA mutations, compared with 4 of 18 (22%) tumors from patients with Lynch syndrome, 2 of 10 (20%) tumors with MLH1 hypermethylation, and 12 of 78 (15%) tumors with microsatellite stability (P < .0001 for patients with double somatic tumors vs other subgroups). Mutations in PIK3CA were detected in all 13 patients with double somatic endometrial cancers (P = .04 compared with other subgroups). We did not detect BRAF mutations in patients with double somatic colorectal tumors or Lynch syndrome. We found highly similar results in a validation cohort from The Cancer Genome Atlas (113 patients with colorectal tumors, 178 endometrial tumors); 100% of double somatic cases had a somatic mutation in PIK3CA (P < .0001 compared with other subgroups). CONCLUSIONS Most patients with colorectal or endometrial tumors with 2 or more somatic (but not germline) mutations in MMR proteins also have mutations in PIK3CA; mutations in PIK3CA are detected at substantially higher frequencies in these double somatic tumors than in other microsatellite-instability subgroups. PIK3CA mutation status might be used to identify a specific group of colorectal tumors, and to select treatment or determine prognosis.
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Affiliation(s)
- Stacey A. Cohen
- University of Washington, Department of Medicine, Division of Medical Oncology, Seattle, WA,Fred Hutchinson Cancer Research Center, Clinical Research Division, Seattle, WA
| | - Emily H. Turner
- Univeristy of Washington, Department of Laboratory Medicine, Seattle, WA
| | | | - Angela Jacobson
- Univeristy of Washington, Department of Laboratory Medicine, Seattle, WA
| | - Ted A. Gooley
- Fred Hutchinson Cancer Research Center, Clinical Research Division, Seattle, WA
| | | | | | - Christina Smith
- Univeristy of Washington, Department of Laboratory Medicine, Seattle, WA
| | - Sheena Scroggins
- Univeristy of Washington, Department of Laboratory Medicine, Seattle, WA
| | - Jonathan F. Tait
- Univeristy of Washington, Department of Laboratory Medicine, Seattle, WA
| | - William M. Grady
- Fred Hutchinson Cancer Research Center, Clinical Research Division, Seattle, WA,University of Washington, Department of Medicine, Division of Gastroenterology, Seattle, WA
| | - Edward H. Lin
- University of Washington, Department of Medicine, Division of Medical Oncology, Seattle, WA,Fred Hutchinson Cancer Research Center, Clinical Research Division, Seattle, WA
| | - David E. Cohn
- The Ohio State University Comprehensive Cancer Center, Division of Gynecologic Oncology, Columbus, OH
| | - Paul J. Goodfellow
- The Ohio State University Comprehensive Cancer Center, Division of Gynecologic Oncology, Columbus, OH
| | - Mark W. Arnold
- The Ohio State University College of Medicine, Department of Surgery, Columbus, OH
| | - Albert de la Chapelle
- The Ohio State University Comprehensive Cancer Center, Department of Molecular Virology, Immunology, and Medical Genetics, Columbus, OH
| | - Rachel Pearlman
- The Ohio State University Comprehensive Cancer Center, Division of Human Genetics, Columbus, OH
| | - Heather Hampel
- The Ohio State University Comprehensive Cancer Center, Division of Human Genetics, Columbus, OH
| | - Colin C. Pritchard
- Univeristy of Washington, Department of Laboratory Medicine, Seattle, WA
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