Frequency and clinicopathologic correlates of KRAS amplification in non-small cell lung carcinoma
ABSTRACT Characterization of the non-small cell lung cancer (NSCLC) genome has suggested that KRAS amplification is one of the commonest molecular abnormalities in NSCLC. However, the prevalence and clinicopathologic significance of KRAS amplification, and its relationship with KRAS activating mutations have not been well-defined. The purpose of this study was to establish the prevalence of KRAS amplification in two separate, large NSCLC cohorts, to define the clinicopathologic features of KRAS-amplified NSCLC in a single uniformly treated cohort, and to investigate the interplay between KRAS amplification and KRAS mutation.
Fluorescence in situ hybridization was utilized to detect KRAS amplification on tissue microarrays constructed from a Swiss cohort of 538 NSCLCs and a series of 402 patients with NSCLC treated in a single institution in New York. DNA sequencing to detect KRAS codon 12 activating mutations was performed on a subset of tumors. Amplification and mutation status were compared with patient baseline characteristics, tumor characteristics, and overall- and disease-free survival.
The prevalence of KRAS amplification was 13.7% in the Swiss cohort and 15.1% in the New York cohort. Among adenocarcinomas, KRAS amplification was associated with larger (mean size 2.8±1.8 cm vs. 2.1±1.3 cm, p=0.003), less well-differentiated tumors (18% vs. 42%, p=0.004) that were more likely to be invasive (95% vs. 77%, p=0.004) and to exhibit angiolymphatic invasion (24% vs. 12%, p=0.04). These differences were statistically significant within the subset of adenocarcinomas harboring activating KRAS mutations, suggesting a synergistic relationship between amplification and mutation. No significant association between KRAS amplification and nodal metastasis or survival was seen.
KRAS amplification is a common molecular alteration in NSCLC, characterizing ∼15% of tumors. This alteration is associated with indicators of local aggressiveness, and may act synergistically with KRAS mutations to promote tumor progression.
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ABSTRACT: Gastric cancer (GC) is a major cause of global cancer mortality. Previous genomic studies have reported that several RTK-RAS pathway components are amplified in GC, with individual tumours often amplifying one component and not others ("mutual exclusivity"). Here, we sought to validate these findings for three RTK/RAS components (FGFR2, HER2, KRAS) using fluorescence in situ hybridisation (FISH) on a series of gastric tumours, cell lines and patient-derived xenografts. Applying dual-colour FISH on 137 gastric tumours (89 FFPE surgical resections and 48 diagnostic biopsies), we observed FGFR2 amplification in 7.3% and HER2 amplification in 2.2% of GCs. GCs exhibiting FGFR2 amplification were associated with high tumour grade (p= 0.034). In FISH positive tumours, striking differences in copy number levels between cancer cells in the same tumour were observed, suggesting intra-tumour heterogeneity. Using a multicolour FISH assay allowing simultaneous detection of FGFR2, HER2, and KRAS amplifications, we confirmed that these components exhibited a mutually exclusive pattern of gene amplification across patients. The FISH data was also strongly correlated with Q-PCR levels and at the protein level by immunohistochemistry. Our data confirms that RTK/RAS components are mutually exclusively amplified in GC, and demonstrates the feasibility of identifying multiple aneuploidies using a single FISH assay. Application of this assay to GC samples, particularly diagnostic biopsies, may facilitate enrollment of GC patients into clinical trials evaluating RTK/RAS directed therapies. However, the presence of intra-tumour heterogeneity may require multiple biopsy samples to be obtained per patient, before a definitive diagnosis can be attained.Cancer Letters 07/2014; 353(2). DOI:10.1016/j.canlet.2014.07.021 · 5.02 Impact Factor
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ABSTRACT: Lymphovascular invasion (LVI) is considered a high-risk pathologic feature in resected non-small cell carcinoma (NSCLC). The ability to stratify stage I patients into risk groups may permit refinement of adjuvant treatment recommendations. We performed a systematic review and meta-analysis to evaluate whether the presence of LVI is associated with disease outcome in stage I NSCLC patients. A systematic search of the literature was performed (1990 to December 2012 in MEDLINE/EMBASE). Two reviewers independently assessed the quality of the articles and extracted data. Pooled hazard ratios (HRs) and 95% confidence intervals (CI) were estimated with a random effects model. Two end points were independently analyzed: recurrence-free survival (RFS) and overall survival (OS). We analyzed unadjusted and adjusted effect estimates, resulting in four separate meta-analyses. We identified 20 published studies that reported the comparative survival of stage I patients with and without LVI. The unadjusted pooled effect of LVI was significantly associated with worse RFS (HR, 3.63; 95% CI, 1.62 to 8.14) and OS (HR, 2.38; 95% CI, 1.72 to 3.30). Adjusting for potential confounders yielded similar results, with RFS (HR, 2.52; 95% CI, 1.73 to 3.65) and OS (HR, 1.81; 95% CI, 1.53 to 2.14) both significantly worse for patients exhibiting LVI. The present study indicates that LVI is a strong prognostic indicator for poor outcome for patients with surgically managed stage I lung cancer. Future prospective lung cancer trials with well-defined methods for evaluating LVI are necessary to validate these results.The Annals of thoracic surgery 01/2014; 97(3). DOI:10.1016/j.athoracsur.2013.11.002 · 3.65 Impact Factor
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