175 Background: Pancreatic cancer is one of the most lethal malignancies, with an estimated 5-year survival rate of 6%, often due to advanced stage at diagnosis. However, there is a small population of patients, even with metastatic disease, who survive 3 years and beyond. Methods: Cases of pancreatic adenocarcinoma diagnosed from 1998 to 2005 were identified in the California Cancer Registry. A multivariate logistic regression model was constructed to predict the outcome of 3+ year survival according to demographic, disease and treatment variables defined a priori: age, gender, race/ethnicity, socioeconomic status (SES), histology, stage, treatment within 4 months of diagnosis (surgery, chemotherapy, and/or radiation), prior cancer history, and treatment at an academic hospital. Results: Among 54,475 cases of pancreatic cancer with ≥3 years of follow-up data available, median survival was 3.5 months. 2,855 patients (5.2%) survived at least 3 years, of whom 19% had remote stage disease at diagnosis. On multivariate analysis, advanced age was associated with decreased odds of long-term survival (p<0.01). By race, Asian/Pacific Islanders (odds ratio (OR) 1.76, p<0.01), Hispanics (OR 1.29, p=0.01) and non-Hispanic blacks (OR 1.24, p=0.14) were more likely to be long-term survivors than non-Hispanic whites. There was a gradient toward increased long- term survival for patients with higher SES (OR 1.49 for highest vs. lowest quintile, p<0.01). Mucinous tumors were associated with higher long-term survival than other adenocarcinomas (OR 2.21, p<0.01). Localized (OR 6.82) and regional stage disease (OR 2.61) showed more long-term survival than remote stage disease, both p<0.01. Surgery (OR 8.20, p<0.01), chemotherapy (OR 1.44, p<0.01), and radiation therapy (OR 1.25, p=0.02) increased the odds of long-term survival, as did treatment at an academic hospital (OR 1.54, p<0.01). Conclusions: In a well- characterized population-based registry with rigorous follow-up, we were able to identify a cohort of long-term survivors of pancreatic adenocarcinoma as well as factors associated with their exceptional survival. Planned future work with this cohort includes case-control studies making use of tumor and germline specimens, as well as survivorship research. No significant financial relationships to disclose.
Identification of KRAS G12V associated clonal neoantigens and immune microenvironment in long-term survival of pancreatic adenocarcinoma
