Comparison of efficacy between adjuvant chemotherapy and chemoradiation therapy for pancreatic cancer: AJCC stage-based approach

BACKGROUND: The adjuvant treatment for patients with resected pancreatic cancer (PC) is not yet standardized. Because the prognosis differs according to the American Joint Committee on Cancer (AJCC) stage, a tailored approach to establish more aggressive treatment plans in high-risk patients is necessary. However, studies comparing the efficacy of adjuvant treatment modalities according to the AJCC stage are largely lacking. AIM: To compare the efficacy of chemotherapy and chemoradiation therapy according to AJCC 8th staging system in patients with PC who underwent surgical resection. METHODS: A total of 335 patients who underwent surgical resection and adjuvant treatment for PC were included. Patients were divided into three groups: Chemoradiation therapy (CRT) group, systemic chemotherapy (SCT) group and combined treatment of chemoradiation plus chemotherapy therapy (CRT-SCT) group. The primary outcomes were differences in overall survival (OS) between the three groups. The secondary outcomes were differences in recurrence-free survival, recurrence pattern and adverse events between the three groups. RESULTS: Patients received CRT (n = 65), SCT (n = 62) and CRT-SCT (n = 208). Overall median OS was 33.3 mo (95% confidence interval (CI): 27.4-38.6). In patients with stage I/II, the median OS was 27.0 mo (95%CI: 2.06-89.6) in the CRT group, 35.8 mo (95%CI: 26.9-NA) in the SCT group and 38.6 mo (95%CI: 33.3-55.7) in the CRT-SCT group. Among them, there was no significant difference in OS between the three groups. In 59 patients with stage III, median OS in the SCT group [19.0 mo (95%CI: 12.6-NA)] and the CRT-SCT group [23.4 mo (95%CI: 22.0-44.4)] was significantly longer than that in the CRT group [17.7 mo (95%CI: 6.8-NA); P = 0.011 and P < 0.001, respectively]. There were no significant differences in incidence of locoregional and distant recurrences between the three groups (P = 0.158 and P = 0.205, respectively). Incidences of grade 3 or higher hematologic adverse events were higher in the SCT and CRT-SCT groups than in the CRT group. CONCLUSION: SCT and CRT-SCT showed significantly longer OS and recurrence-free survival than CRT in patients with AJCC stage III, while there was no significant difference in OS between the CRT, SCT and CRT-SCT groups in patients with AJCC stage I/II. Different adjuvant therapy according to AJCC stage can be applied in patients with PC.