CA19-9 response and CT-imaging predict resectability of locally advanced pancreatic carcinoma following neoadjuvant chemotherapy

Abstract

Background: Neoadjuvant chemotherapy, especially FOLFIRINOX, has the ability to downsize locally advanced pancreatic cancer (LAPC). Unfortunately current radiological modalities are unable to distinguish between fibrosis and viable tumor. As a result, patients can be considered unresectable if the tumor response is underestimated. Therefore, more accurate predictors for resectability of LAPC are of interest. We hypothesize that decreasing CA19-9 serum levels combined with CT imaging in response to chemotherapy may be useful prognostic tools to predict resectability. Methods: LAPC patients following neo-adjuvant FOLFIRINOX/gemcitabine treatment were prospectively registered. Inclusion criteria were; PA proven LAPC, availability of CA19-9 serum levels and CT-imaging pre-and post-neoadjuvant therapy. All imaging was analyzed by a specialized radiologist according to the RECIST-criteria. Results: 36 out of 54 patients underwent exploratory laparotomy. Eleven patients (20%) underwent a resection. All but one of these had decreasing CA19-9 serum levels (median -83%, interquartile range 38%). The PPV of both CT-regression and a decrease in CA19-9 levels of ≥30% in the total cohort was 100%, with an equal specificity of 100%. The negative predictive value of an increase in CA19-9 of ≥30% is 94%. Conclusion: Patients with decreasing CA19-9 levels following neoadjuvant chemotherapy have a higher likelihood of resectability. Increasing CA19-9 levels could therefore be a relative contra-indication for surgical exploration.