Prognostic value of the volume time index (VTI) ratio for patients with appendiceal cancer with peritoneal carcinomatosis treated by cytoreductive surgery and hyperthermic intraperitoneal chemotherapy (CRS/HIPEC).

e15704 Background: Completeness of cytoreduction score (CC-score) and tumour volume (as expressed by the peritoneal cancer index (PCI)) have been demonstrated as important post-operative prognostic factors in those patients with appendix cancer with peritoneal metastases undergoing CRS/HIPEC. A previous analysis included a pre-operative factor and demonstrated the tumour marker to volume index (CA19-9/PCI) in patients who had low grade appendiceal cancer with peritoneal metastases was an independent prognostic factor for overall survival (OS). This analysis aims to evaluate VTI as a prognostic factor in low- and high-grade appendix neoplasms with peritoneal dissemination managed with CRS/HIPEC. Methods: A retrospective cohort study of all patients diagnosed with appendiceal cancer with peritoneal dissemination managed with CRS/IPC from 1996 to 2017 was performed by analysing the survival effect of the ratio of tumour volume to the time between initial tumour resection and CRS/HIPEC. VTI was stratified into low versus high groups, and tumour grade was divided into low grade: diffuse peritoneal adenomucinosis (DPAM); and high grade: peritoneal mucinous carcinomatosis (PMCA). Results: Two hundred and sixty-four patients were included. For both DPAM and PMCA, there was no statistically significant difference in overall survival between patients with a low versus high VTI. For both low and high VTI in DPAM, the median survival was not reached, p= 0.586. For PMCA, those with a low VTI had an overall survival of 63 months (95%CI 48-NR), versus those with a high VTI 69 months (95%CI 45-NR), p= 0.97. There was no statistically significant difference in the median recurrence free survival (RFS) between low and high VTI for both DPAM and PMCA. Conclusions: The volume to time ratio for appendix cancer with peritoneal dissemination was not an independent prognostic indicator for overall survival in patients undergoing CRS/HIPEC, suggesting that this index is not a valuable pre-operative planning tool.

The rise in appendix cancer incidence: 2000-2009.

e12506 Background: Cancer of the appendix is a rare and potentially aggressive malignancy. The objectives of this study were to characterize secular demographic patterns of disease and to determine survival by using a population-based data source. Methods: Using the Surveillance Epidemiology and End Results database we identified all appendiceal neoplasms reported to the registry between 2000 and 2009.Tumors were classified as carcinoid, adenocarcinoma, mucinous and signet ring cell carcinoma. We compared overall incidence, age distribution by tumor type and overall survival rates by extent of disease at diagnosis. To assess whether the incidence rate, tumor size, and cancer stage changed over time, the Cochrane-Armitage trend test was used. Logistic regression models were used to determine the odds of distant disease at diagnosis and Cox proportional-hazards modeling was used to identify the factors associated with overall survival rates. Results: We identified 4,765 patients with appendix cancer. The incidence of appendiceal cancer increased by 54% from 2000 (0.63 per 100,000) to 2009 (0.97 per 100,000). Incidence rates increased across all tumor types, stages, age groups and gender. The most common malignancies were mucinous (38%), followed by carcinoids (28%) adenocarcinoma (27%), and signet ring cell carcinoma (7%). Distant stage at diagnosis was most common among, signet ring cell tumors (60%). Larger tumor size and older patient age were significantly associated with higher relative odds of distant disease at diagnosis (P < .0001). Tumor type, older age, black race, males, tumor size of 2 cm and greater, cancer stage and registry were significantly associated with higher relative hazard of death (P< .0001). Mean 5-year survival was 55% for carcinoid patients, 49% for adenocarcinoma, 50% for mucinous and 38% for the signet ring cell cohort. Conclusions: Although appendiceal cancer is rare, the incidence increased significantly in the U.S. from 2000 to 2009. The cause of this trend is not obvious. We did not see increases differentially associated with stage, histology, registry or demographic characteristics. Further investigation is needed to examine factors underlying this increase. This research was generously supported by the Betti Boers Maloney Appendix Cancer Research Fund at the University of Minnesota Foundation.

Molecular profiles of appendiceal adenocarcinoma: The UCSD experience.

397 Background: Appendix cancer is rare, which precludes its study in randomized trials. As such, no evidence-based guidelines currently exist regarding the optimum systemic therapy for this disease entity. Typically, these patients are treated with regimens for colorectal carcinoma. Previous studies have shown high intra-tumoral mRNA levels of EGFR were significantly associated with response to irinotecan based chemotherapy, and that mucinous colorectal cancer overexpresses markers of resistance to 5-FU and oxaliplatin. We examined pharmacogenomics markers for appendiceal cancer and colon cancer to understand underlying similarities and differences between these tumor types. Methods: Intratumoral gene expression levels were assessed from paraffin-embedded tissue samples, using laser capture microdissection and quantitative real-time PCR from 69 colorectal and 34 appendiceal adenocarcinomas. A retrospective chart review was performed to correlate gene expression with overall survival. KRAS and BRAF mutational analyses and gene expression levels of ERCC1, TS, and EGFR were correlated with overall survival. Results: Appendiceal tumors had significantly higher expression of EGFR, (2.66 vs 1.4, p<.0001). No BRAF V600E mutations were found in the appendiceal tumors, incidence was 8.97% of the colon patients. UPDATE: In appendix cancer, KRAS mutations were noted in 65.5% of patients, there were no BRAF mutations. Median ERCC1, TS, EGFR, and VEGFR2A expression was 1.4, 1.21, 1.57, 2.19 respectively. Patients with metastatic appendiceal cancer had a significantly longer median OS than metastatic colon patients, (113 mo vs 43.9 mo, p = .0154). For appendiceal cancer patients, there was no significant correlation between any of the biomarkers and OS, although the sample size was underpowered for such an analysis. Conclusions: Metastatic appendiceal cancer patients have significantly better outcomes than metastatic colon cancer patients. Molecular analyses reveal significant differences between these tumor types. Further molecular study of appendiceal cancer is needed, as this study and others suggest fundamental differences in biology from colon cancer.