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Preparation of Formalin-fixed Paraffin-embedded Tissue Cores for both RNA and DNA Extraction
Published on: August 21, 2016
PIK3CA mutation is a favorable prognostic factor in esophageal cancer: molecular profile by next-generation
Tomoya Yokota1, Masakuni Serizawa2, Ayumu Hosokawa3
1Division of Gastrointestinal Oncology, Shizuoka Cancer Center, 1007 Shimonagakubo Nagaizumi-cho Sunto-gun, Shizuoka, 411-8777, Japan.
Background:
Practical and reliable genotyping procedures with a considerable number of samples are required not only for risk-adapted therapeutic strategies, but also for stratifying patients into future clinical trials for molecular-targeting drugs. Recent advances in mutation testing, including next-generation sequencing, have led to the increased use of formalin-fixed paraffin-embedded tissue. We evaluated gene alteration profiles of cancer-related genes in esophageal cancer patients and correlated them with clinicopathological features, such as smoking status and survival outcomes.
Methods:
Surgically resected formalin-fixed, paraffin-embedded tissue was collected from 135 consecutive patients with esophageal cancer who underwent esophagectomy. Based on the assessment of DNA quality with a quantitative PCR-based assay, uracil DNA glycosylase pretreatment was performed to ensure quality and accuracy of amplicon-based massively parallel sequencing. Amplicon-based massively parallel sequencing was performed using the Illumina TruSeq® Amplicon Cancer Panel. Gene amplification was detected by quantitative PCR-based assay. Protein expression was determined by automated quantitative fluorescent immunohistochemistry.
Results:
Data on genetic alterations were available for 126 patients. The median follow-up time was 1570 days. Amplicon-based massively parallel sequencing identified frequent gene alterations in TP53 (66.7%), PIK3CA (13.5%), APC (10.3%), ERBB4 (7.9%), and FBXW7 (7.9%). There was no association between clinicopathological features or prognosis with smoking status. Multivariate analyses revealed that the PIK3CA mutation and clinical T stage were independent favorable prognostic factors (hazard ratio 0.34, 95% confidence interval: 0.12-0.96, p = 0.042). PIK3CA mutations were significantly associated with APC alterations (p = 0.0007) and BRAF mutations (p = 0.0090).
Conclusions:
Our study provided profiles of cancer-related genes in Japanese patients with esophageal cancer by next-generation sequencing using surgically resected formalin-fixed, paraffin-embedded tissue, and identified the PIK3CA mutation as a favorable prognosis biomarker.
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