P-0109 Survival Analysis of Maintenance Therapy with Capecitabine in Patients with Resected Pancreatic Adenocarcinoma after Adjuvant Therapy, a Retrospective Cohort Study

Abstract

IntroductionThe 5-year survival of pancreatic adenocarcinoma (PAC) with surgery alone is less than 10%, and with adjuvant chemotherapy increases to about 20%. The original GITSG adjuvant study demonstrated a survival benefit compared to surgery, and could have been attributed to the weekly IV bolus of 5FU for 2 years, in addition to chemoradiation. In theory, the prolonged exposure to therapy could maintain pressure on dormant cancer cells that remain in G0 arrest, and kill them as they infrequently enter G1/S phase. To evaluate this hypothesis, we retrospectively evaluated patients at Georgetown University Hospital (GUH) who were treated with maintenance capecitabine, and compared to the patients who completed standard adjuvant gemcitabine at GUH and at the Ohio State University (OSU). MethodsPatients in the Georgetown/Lombardi Cancer Center and the Ohio State University EMR were sought for PAC that was resected with curative intent, and had received standard adjuvant chemotherapy with or without chemoradiation. After 6 months of gemcitabine without recurrence, the study group received maintenance capecitabine for up to 2 years, and the control groups received no further therapy until disease relapse. Only patients with complete follow-up survival data were analyzed. Results20 patients from GUH met the criteria as the maintenance group, and 58 and 14 patients from GUH and OSU respectively as the control group. In the maintenance group, capecitabine was usually given 1000mg orally twice a day, Monday through Friday following adjuvant therapy, for an indefinite period, up to 2 years. Patients received capecitabine for median duration of 12.5 months (2 to 24 months), and the median follow-up duration was 33 months (16 to 78 months). The median overall survival (OS) for the maintenance group was 48 months. The 2 year OS was 94%, and 5 year OS was 40%. The median recurrence free survival (RFS) was 39 months. The 2 year RFS was 67%, and the 5 year RFS was 25%. Common toxicities were mild hand-and-foot syndrome and fatigue. Four patients discontinued capecitabine due to toxicities: febrile neutropenia, severe fatigue, weight loss and diarrhea. The GUH control group was of comparable staging, and the median OS was 22 months, 2 year OS was 86.6%, 5 year OS rate was 16%, median RFS was 13 months, 2 year RFS was 19%. For the OSU control group, the median OS was 16.33 months, 2 yr OS was 35.7%, median RFS was 14.8 months, 2yr RFS was 20%. ConclusionIn this retrospective controlled cohort study, capecitabine maintenance therapy following adjuvant therapy in resected PAC is associated with a significantly (p<0.05) higher OS and RFS compared to the control group. The outcome of the capecitabine maintenance group is promising in the context of survival data from the two institutions and historical record in publications. This approach should be studied in a RCT.