Prognostic value of positron emission tomography and preoperative CA19-9 in patients treated on a prospective phase II trial of neoadjuvant therapy and surgery.

Abstract

e15766 Background: The role of 18F-fluorodeoxyglucose positron emission tomography (FDG-PET) in the staging of pancreatic cancer (PC) has not been well defined. We evaluated the prognostic value of FDG-PET imaging in patients with localized PC enrolled in a prospective trial of personalized molecular-directed neoadjuvant therapy. Methods: Pretreatment FDG-PET was classified as high or low based on a standardized uptake value (SUV) cutpoint of 7.2 (population median). Carbohydrate antigen 19-9 (CA19-9) was measured after the completion of neoadjuvant therapy (preoperative) and classified as normal (≤35 U/mL) or elevated. Results: Pretreatment FDG-PET imaging was performed on 100 consecutive patients; SUV was high in 50 and low in 50. Preoperative CA19-9 values were available in 99 of 100 patients; 54 (55%) were elevated and 45 (45%) were normal. Of the 100 patients, 81 completed neoadjuvant therapy and surgery, and 19 were not resected. Among the 81 resected patients, SUV was high in 37 (46%) and low in 44 (54%); preoperative CA19-9 was elevated in 40 (49%) and normal in 41 (51%). The median overall survival (OS) for all patients was 39 months; 45 months for who completed all intended neoadjuvant therapy and surgery and 9 months for patients who were not resected. The median OS for patients with normal CA19-9/low SUV, normal CA19-9/high SUV, elevated CA19-9/low SUV, and elevated CA19-9/high SUV were not reached, 35, 24, and 18 months, respectively (p = 0.0001). Conclusions: Pretreatment FDG-PET avidity and preoperative CA19-9 are important prognostic markers and may be used to estimate the anticipated benefit of surgery; information of immediate clinical significance for both treatment sequencing and the application of surgery to patients who are frequently of advanced age or high-risk.