The degree of segmental aneuploidy measured by total copy number abnormalities to predict survival and recurrence in superficial gastroesophageal adenocarcinoma.
62 Background: Prognostic biomarkers are needed for superficial gastroesophageal adenocarcinoma (EAC) to predict clinical outcomes and select therapy. Although recurrent mutations have been characterized in EAC, little is known about their clinical and prognostic significance. Aneuploidy is predictive of clinical outcome in many malignancies but has not been evaluated in superficial EAC. SNP arrays offer the opportunity to evaluate segmental aneuploidy at high resolution throughout the genome. Methods: We quantified copy number changes in 41 superficial EAC using Affymetrix SNP 6.0 arrays. We identified recurrent chromosomal gains and losses and calculated the total copy number abnormality (CNA) count for each tumor as a measure of aneuploidy. We correlated CNA count with overall survival and time to first recurrence in univariate and multivariate analyses. Results: Recurrent segmental gains and losses involved multiple genes, including: HER2, EGFR, MET, CDK6 , KRAS (recurrent gains); and FHIT, WWOX, CDKN2A/B, SMAD4, RUNX1 (recurrent losses). There was a 40-fold variation in CNA count across all cases. Tumors with the lowest and highest quartile CNA count had significantly better overall survival (p=0.032, log rank test) and time to first recurrence (p=0.010, log rank test) compared to those with intermediate CNA counts. In multivariate Cox analysis, there was a 3.4-fold (95% CI, 1.1–10.4) increased hazard of death among cases with intermediate CNA counts after adjusting for other predictors of survival (N stage, angiolymphatic invasion and tumor size). Similarly, there was a 7.3-fold (95% CI, 1.5-34) increased risk of recurrence for these patients. Conclusions: SNP arrays facilitate the assessment of recurrent chromosomal gain and loss and allow high resolution, quantitative assessment of segmental aneuploidy (total CNA count).The non-monotonic association of segmental aneuploidy with survival has been described in other tumors such as breast and ovarian carcinoma. The degree of segmental aneuploidy is a promising prognostic biomarker in a potentially curable form of EAC.