Clinical characteristics of long term survivors in inoperable pancreatic cancer : 8-year cohort analysis in Korea

Abstract

Background: Inoperable pancreatic ductal adenocarcinoma (PDAC) is known to be associated with a poor prognosis, yet a favorable outcome can be expected in some patients. The clinical characteristics of such long-term survivors with inoperable PDAC have not been established. Here we investigated the clinical significance and treatment outcomes of long-term survivors with PDAC.Methods: Patients with PDAC who had been evaluated at our institution between January 2002 and December 2009 were identified from the National Cancer Information Center of Korea cohort. All patients were histopathologically confirmed as having adenocarcinoma of the pancreas. A long-term survivors (LS) group, consisting of patients who had survived for more than 24 months with locally advanced pancreatic cancer (LAPC) or 18 months with metastatic disease after diagnosis, was compared to a short-term survivors (SS) group, consisting of patients who had survived less than 9 months with LAPC or 6 months with metastatic disease.Results: The median overall survival (OS) was 15.8 months for LAPC and 6.9 months for metastatic disease. Among patients with LAPC, 23 patients (17%) were in the LS group and 59 patients (45%) were in the SS group. Patients in the LS group had a lower Eastern cooperative oncology group performance status (ECOG PS) (p=0.041), higher serum albumin level (p=0.032), and lower CA19-9 level (p=0.005) at diagnosis. The majority of the LS group patients received gemcitabine/cisplatin chemoradiation compared to other regimens or chemotherapy alone (p=0.039). Among metastatic cases, 22 patients (6%) were in the LS group and 208 patients (59%) were in the SS group. Patients in the LS group were younger (p=0.044), had lower ECOG PS (p=0.016), less peritoneal metastasis (p=0.038), lower BUN (p=0.007), lower creatinine (p=0.025), higher albumin (p=0.002), lower CA19-9 level (p=0.001) and a greater decrease in CA19-9 (p=0.001). The majority of the LS group received gemcitabine/cisplatin chemotherapy compared to other regimens or chemoradiation (p=0.027). In multivariate analysis for OS in LAPC, lower ECOG PS (HR 0.36, 95%CI[0.19-0.66], p=0.001), and lower initial CA19-9 level (HR 0.40 [0.25-0.65], p<0.001, cut-off CA 19-9 value : 1000 U/mL) were related to OS. In metastatic disease, young age (HR1.02 [1.00-1.03], p=0.027), lower ECOG PS (HR 0.71 [0.52-0.97], p=0.032), peritoneal metastasis (HR1.48 [1.13-1.94], p=0.005), high serum albumin level (HR0.53 [0.42-0.67], p<0.001), low initial CA19-9 level (HR0.70, [0.54-0.90], p=0.006) and CA19-9 variation (HR1.08 [1.02-1.15], p=0.008) were related to OS.Conclusion: Baseline analysis of a cohort study revealed that good performance status and a lower initial CA19-9 level at diagnosis seemed to be associated with long-term survival in LAPC. In metastatic pancreatic cancer, younger age, absence of peritoneal metastasis, good performance status, higher serum albumin, lower initial CA19-9, and a larger decrease in CA19-9 were independent factors related to long-term survival. If the molecular biological features of long-term survivors could be revealed, future treatments could be designed for individual pancreatic cancer patients.