715P - Timing and Patterns of Disease Progression Following Concurrent Radiochemotherapy in Patients with Unresectable Locally-Advanced Pancreas Cancer

Abstract

ABSTRACT Background Timing and patterns of disease progression in patients with unresectable locally-advanced pancreas carcinoma (LAPC) treated with definitive concurrent radiochemotherapy (C-RCT) was analyzed. Materials and method Fifty-two patients with histologic proof of LAPC underwent 50.4 Gy (1.8 Gy per fraction) of C-RCT with 5-FU followed by maintenance gemcitabine. Disease was considered to be unresectable if contrast-enhanced CT or staging laparoscopy/laparotomy revealed a low likelihood of complete resection and/or any of the following: involvement of superior mesenteric artery/cealiac trunk, encasement of 180 degrees or more of the circumference of superior mesenteric/portal vein, and/or evidence of narrowing of or thrombus within the superior mesenteric/portal vein. Elective nodal irradiation was not adopted. Primary aim was to assess timing and patterns of disease progression. Results Treatment was well tolerated and all patients were able to receive intended C-RCT regimen. At median 17.4 months of follow-up 38 (73.1%) were dead. Median, 1- and 2-year overall- and progression-free survival estimates were 16.1 months, 61.2% and 22.6%, and 7.4 months, 27% and 12.3% respectively. Analysis for timing of disease progression revealed that 7 (13.5%), 15 (28.8%), 20 (38.5%), and 22 (42.3%) patients experienced disease progression at 3, 4, 5, and 6 months, respectively, since initiation of R-RCT. Interestingly, although there were no isolated local or regional failures during this early follow-up period, all failures were presented as distant metastases with/without local/regional disease progression. Conclusion Results of this study demonstrated that, despite aggressive staging and treatment strategies, early distant disease progression are common source of treatment failures in unresectable LAPC. Present findings impact the urgent need for more efficacious chemotherapeutic agents for control of distant metastatatic tumor deposits and better treatment strategies, such as induction chemotherapy followed by C-RCT, to eliminate early treatment failures and unnecessary and futile C-RCT in metastatic disease state. Disclosure All authors have declared no conflicts of interest.