Clinical outcomes of different irradiation ranges in definitive intensity-modulated radiotherapy for esophageal cancer

Abstract

Objective: To explore the therapeutic efficacy and safety of elective nodal irradiation (ENI) and involved field irradiation (IFI) in intensity-modulated radiotherapy for esophageal cancer, screen the patients suitable to undergo ENI radiotherapy and provide evidences for individual treatment of esophageal cancer. Methods: A retrospective analysis was performed on the clinical data of 924 patients with esophageal cancer who received definitive intensity-modulated radiotherapy in our hospital from January 2006 to December 2015. Among them, 272 patients received ENI and the other 652 patients received IFI. The clinicopathologic characteristics of 272 cases in ENI group and 652 cases in IFI group, who were recruited according to the balance of propensity score matching method, were compared. The Kaplan-Meier method was used to calculate 1-year, 3-years and 5-years local-regional failure-free survival (LRFFS), progression-free survival (PFS) and overall survival (OS) rates. The univariate and multivariate analysis of prognostic factors were also determined by Cox proportional hazard model and Long-rank test. Results: The clinicopathologic characteristics of these two group were not significantly different (P>0.05). The median follow-up time was 85.9 months and the follow-up rate was 95.9%. The 1-year, 3-years, 5-years PFS rates of the ENI groups were 65.3%, 31.7%, 18.4%, respectively, higher than 54.0%, 20.9%, 12.7% of the IFI group (P=0.001). The 1-year, 3-years, 5-years OS rates of the ENI groups were 79.0%, 43.7%, 24.9%, respectively, higher than 75.0%, 31.8%, 17.2% of the IFI group (P=0.003). In multivariate analysis, the sex, tumor volume, N stage and radiation field were independent factors for PFS and OS (P<0.05). Subgroup analysis showed that patients with male, age≤66 year, cervical and upper-thoracic location, tumor length≤6 cm, T1-2 stage, N0-1 stage, Ⅰ-Ⅱ stage, tumor volume≤50 cm(3), dosage>60 Gy and≤2 cycles of chemotherapy in the ENI group had a better survival rate than those in the IFI group (P<0.05). The total failure rate, local-regional failure rate in ENI group were significantly lower than those of IFI group (P=0.001, P=0.004). The incidence of bone marrow depression≥ grade 2 and 3 in ENI group was higher than that of the IFI group (P<0.05). However, the incidences of radioactive esophagitis≥ grade 3, radioactive pneumonia and late adverse reactions were not significantly different between these two groups (P>0.05). Conclusion: Compared with IFI, ENI can significantly improve the long-term survival for young, early TN stage and cervical/upper-thoracic esophageal cancer patients underwent chemotherapy.