Molecular profiling of appendiceal epithelial tumors using massively parallel sequencing to identify somatic mutations.

BACKGROUND: Some epithelial neoplasms of the appendix, including low-grade appendiceal mucinous neoplasm and adenocarcinoma, can result in pseudomyxoma peritonei (PMP). Little is known about the mutational spectra of these tumor types and whether mutations may be of clinical significance with respect to therapeutic selection. In this study, we identified somatic mutations using the Ion Torrent AmpliSeq Cancer Hotspot Panel v2. METHODS: Specimens consisted of 3 nonneoplastic retention cysts/mucocele, 15 low-grade mucinous neoplasms (LAMNs), 8 low-grade/well-differentiated mucinous adenocarcinomas with pseudomyxoma peritonei, and 12 adenocarcinomas with/without goblet cell/signet ring cell features. Barcoded libraries were prepared from up to 10 ng of extracted DNA and multiplexed on single 318 chips for sequencing. Data analysis was performed using Golden Helix SVS. Variants that remained after the analysis pipeline were individually interrogated using the Integrative Genomics Viewer. RESULTS: A single Janus kinase 3 (JAK3) mutation was detected in the mucocele group. Eight mutations were identified in the V-Ki-ras2 Kirsten rat sarcoma viral oncogene homolog (KRAS) and GNAS complex locus (GNAS) genes among LAMN samples. Additional gene mutations were identified in the AKT1 (v-akt murine thymoma viral oncogene homolog 1), APC (adenomatous polyposis coli), JAK3, MET (met proto-oncogene), phosphatidylinositol-4,5-bisphosphate 3-kinase (PIK3CA), RB1 (retinoblastoma 1), STK11 (serine/threonine kinase 11), and tumor protein p53 (TP53) genes. Among the PMPs, 6 mutations were detected in the KRAS gene and also in the GNAS, TP53, and RB1 genes. Appendiceal cancers showed mutations in the APC, ATM (ataxia telangiectasia mutated), KRAS, IDH1 [isocitrate dehydrogenase 1 (NADP+)], NRAS [neuroblastoma RAS viral (v-ras) oncogene homolog], PIK3CA, SMAD4 (SMAD family member 4), and TP53 genes. CONCLUSIONS: Our results suggest molecular heterogeneity among epithelial tumors of the appendix. Next generation sequencing efforts have identified mutational spectra in several subtypes of these tumors that may suggest a phenotypic heterogeneity showing mutations that are relevant for targeted therapies.

Surveillance With Serial Imaging and CA 19-9 Tumor Marker Testing After Resection of Pancreatic Cancer: A Single-Center Retrospective Study.

OBJECTIVES: Most patients receiving curative-intent surgery for pancreatic cancer will experience cancer recurrence. However, evidence that postoperative surveillance testing improves survival or quality of life is lacking. We evaluated the use and characteristics of surveillance with serial imaging and CA 19-9 tumor marker testing at an NCI-designated comprehensive cancer center. METHODS: We conducted a retrospective cohort study of patients who entered surveillance after curative-intent resection of pancreatic adenocarcinoma. We abstracted information from the electronic medical record about oncology office visits, surveillance testing (cross-sectional imaging and CA 19-9 tumor marker testing), and pancreatic cancer recurrence, with follow-up through 2 years after pancreatectomy. We conducted analyses to describe the use of surveillance testing and to characterize the sensitivity and specificity of CA 19-9 tumor marker testing for the identification of cancer recurrence. RESULTS: We identified 90 patients entering surveillance after pancreatectomy. CA 19-9 was the most frequently used surveillance test, followed by CT imaging. Forty-seven patients (52.2%) experienced recurrence within two years of pancreatectomy. Recurrence risk was 58.8% versus 31.8% in patients with elevated versus normal CA 19-9 at diagnosis ( P =0.03). Elevated CA 19-9 at any point during surveillance was significantly associated with 2-year recurrence risk ( P <0.001). Elevated CA 19-9 had a sensitivity of 83% (95% CI 0.72-0.95) and specificity of 87% (0.76-0.98) for identification of recurrence within 2 years of pancreatectomy. CONCLUSIONS: CA 19-9 demonstrates clinical validity for identifying recurrence of pancreatic cancer during surveillance. Surveillance approaches with reduced reliance on imaging should be prospectively evaluated.

Merkel cell polyomavirus and extrapulmonary small cell carcinoma.

The Merkel cell polyomavirus (MCV) is involved in the development of up to 100% of Merkel cell cancer (MCC) cases. Early studies have reported that the virus was infrequently detected in other small cell or neuroendocrine lung carcinomas, which share histological features with MCC. The present study investigated the presence of MCV in cases of extrapulmonary small cell carcinoma (ESCC), which also shares histological features with MCC. A total of 25 cases of ESCC that were diagnosed between 2004 and 2009 were identified at The Dartmouth Hitchcock Medical Center. Archived tissue was available for testing in 16 of these cases. A total of 11 tissue specimens of MCC were used as positive controls. DNA that was extracted from the archived tissue was subjected to five separate quantitative (q)PCR assays for the detection of four MCV genomic targets. MCV DNA was detected in 3/16 (19%) of the ESCCs and in all 11 MCCs. In the three MCV-positive ESCCs, the viral target was only detected by either one or two of the PCR assays. In 8/11 MCV-positive MCCs, the DNA tested positive by either three or all four assays and the remaining three MCCs tested positive by either one or two assays. The ß-globin endogenous control was detected in all the samples that were tested. Although MCC and ESCC share numerous histological features, MCV is detected at a lower frequency in ESCC. The possible role for MCV in the etiology of ESCC remains uncertain and may account for the rare cases of ESCC with no other identifiable etiology. The failure of other assays to detect MCV may be due to sequence variability in the MCV genome.