AbstractBackgroundThe prognosis for unresectable locally advanced pancreatic cancer (LAPC) is still poor, and the best therapeutic option is still unknown. The common treatments for LAPC, concurrent chemoradiotherapy (CCRT), ¹²⁵I seed implantation combined with chemotherapy (125IC), and chemotherapy alone (CA), were studied. In addition, we looked into the impact of radiation dose on the survival of patients receiving chemoradiotherapy.MethodsThis study included 202 patients with unresectable LAPC who were separated into three groups based on treatment methods: CCRT, 125IC, and CA. Overall survival (OS) and progression‐free survival (PFS) were calculated using the Kaplan‐Meier and Cox regression methods. The differences between groups were analyzed using the chi‐square test and the Fisher exact test. All three groups were compared at the same time and then in pairs. To investigate the impact of radiation dose on survival, patients with CCRT were divided into groups based on radiation dose (<54.9 Gy/≥54.9 Gy) or biological effective dose (BED) of radiotherapy (<65.32 Gy/≥65.32 Gy). Univariate and multivariate analyses were also performed to explore the factors associated with prognosis.ResultsPatients who received CCRT had a superior OS rate than those who received 125IC or CA (p = 0.009). Multivariate analyses showed that ECOG score 2 (p<0.001) and 125IC (p=0.012) treatment method were substantially associated with poor OS, while being male (p=0.005) and ECOG score 2 (p<0.001) were significantly associated with poor PFS. When comparing the effects of radiation dose on survival, concurrent chemotherapy with high‐dose radiotherapy (CCHRT) was found to have a better OS rate (p=0.003) than concurrent chemotherapy with low‐dose irradiation (CCLRT). PFS, on the other hand, did not differ statistically in any of the groups (p>0.05). Multivariate analyses showed that age ≥ 64.5 years (p=0.038), ECOG score 2(p=0.001), and CCLRT (p=0.001) were significantly associated with poor OS, while being male (p=0.023) was associated with poor PFS.ConclusionsPatients who received CCRT for unresectable LAPC had a greater OS rate than those who received 125IC or CA. Within permitted bounds, CCHRT outperformed CCLRT in terms of OS.