The Sequential Radiographic Effects of Preoperative Chemotherapy and (Chemo)Radiation on Tumor Anatomy in Patients with Localized Pancreatic Cancer

Background: The incidence and magnitude of indicators of radiographic response of pancreatic cancer to systemic chemotherapy and (chemo)radiation administered prior to anticipated pancreatectomy are unclear. Methods: Sequential computed tomography scans of 226 patients with localized pancreatic cancer who received chemotherapy consisting of 5-fluorouracil, leucovorin, oxaliplatin, and irinotecan (FOLFIRINOX) or gemcitabine and nanoparticle albumin-bound paclitaxel (GA) with or without (chemo)radiation and who subsequently underwent surgery with curative intent from January 2010 to December 2018 at The University of Texas MD Anderson Cancer Center and Verona University Hospital were re-reviewed and compared. Results: Overall, 141 patients (62%) received FOLFIRINOX, 70 (31%) received GA, and 15 (7%) received both; 164 patients (73%) received preoperative (chemo)radiation following chemotherapy and prior to surgery; and 151 (67%), 70 (31%), and 5 (2%) patients had Response Evaluation Criteria in Solid Tumors (RECIST) stable disease, partial response, and progressive disease, respectively. The tumors of 29% of patients with borderline resectable or locally advanced cancer were downstaged after preoperative therapy. Radiographic downstaging was more common with chemotherapy than with (chemo)radiation (24% vs. 6%; p = 0.04), and the median tumor volume loss after chemotherapy was significantly greater than that after (chemo)radiation (28% vs. 17%; p < 0.01). Conclusions: Less than one-third of patients treated with FOLFIRINOX or GA with or without (chemo)radiation experienced either RECIST partial response or radiographic downstaging prior to surgery. The incidence of tumor downstaging was higher and the magnitude of tumor volume loss was greater following chemotherapy than after (chemo)radiation.