Abstract 1885: Quantitative Textural Analysis (QTA) in CT imaging: Identifying markers for genetic instability and overall survival in cohort of previously treated metastatic pancreatic cancer (mPC)

Abstract

Abstract PURPOSE. To explore the use of helical CT-derived Quantitative Textural Analysis (QTA) parameters in identifying elevated rates of intrachromosomal copy number aberrations in mPC and secondarily in revealing post-treatment QTA prognostic markers. MATERIALS AND METHODS. Metastatic tumor sites were biopsied and molecularly profiled in a cohort patients with mPC (n=35). 85% of the cohort had 1-3 previous treatment regimens, and the remaining 15% had 4-6. Intrachromosal copy number were assessed by CGH in tumor specimens, and patients were treated with commercially available cytotoxic regimens based on these individual molecular profiling results1. Patients with available pre-biopsy transverse abdominal portal-venous phase CT scans were obtained for retrospective analysis (n=17). Analysis of pre-biopsy pancreas imaging was performed by drawing regions of interest around the primary pancreas adenocarcinoma (n=15) and the normal pancreas tissue when available (n=12). Two patients did not have any quantifiable imaging due to surgery or local structural obfuscation and were not included in our cohort. There were 9 males and 6 females all with stage IV cancer from 34 - 71 years old (median 59). QTA parameters were derived using the TexRAD platform at texture filtering densities of medium (3 pixels) and coarse (5 pixels). There values were compared to intrachromosomal copy number aberrations per tumor and overall survival post-treatment using a Spearman's rank correlation coefficient. RESULTS. Intrachromosomal copy number aberrations (median: 14; range: 5 - 52) were negatively correlated with the kurtosis value of the primary tumor mass (median: -0.146; range: -0.810 - 0.633) using medium texture filtering (p = 0.034, n = 15). Secondary analysis of the normal pancreas with coarse texture filtering yielded a correlation between reduced overall survival time post-treatment and increasing entropy (p = 0.0014, n = 12). Using entropy as a cutoff value (median: 4.165; range 2.686 - 4.891), median overall survival was greater in the entropy < 4.165 group versus the entropy > 4.165 group (6.1 v 2.0 months, respectively; hazards ratio [HR] = 11.5; 95% CI 1.36 - 97.4; p = 0.025, n = 12). Median survival for the entire cohort was 120 days and ranged from 1 day to 372 days post-treatment. CONCLUSION. This exploratory study with admittedly limited sample size raises interesting questions about the use of QTA parameters as diagnostic tools and/or biopsy adjuncts in assessing pancreatic adenocarcinoma susceptibility to commercially available cytotoxics. Secondarily, entropy, a potential marker of heterogeneity and inflammation in the normal pancreas, represents an intriguing possibility for gauging prognosis in mPC. (Clinical trial supported by a grant from the SU2C/AACR-pancreatic dream team) REFERENCES. 1. Ramanathan RK et al AACR Annual Meeting. LB-221. 2012. Citation Format: David H. Campbell, Michael Barrett, Ramesh K. Ramanathan, Daniel D. Von Hoff, Ronald Korn. Quantitative Textural Analysis (QTA) in CT imaging: Identifying markers for genetic instability and overall survival in cohort of previously treated metastatic pancreatic cancer (mPC). [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 1885. doi:10.1158/1538-7445.AM2014-1885