1576P - Comparison of efficacy and safety of first-line systemic therapy combined with or without radiotherapy for stage IVb esophageal squamous cell carcinoma: A propensity score matching analysis

Background

The role of additional radiotherapy (RT) to systemic therapy including chemotherapy plus anti-PD-1 for metastatic esophageal squamous cell carcinoma (ESCC) is not clear. This analysis aims to compare the survival and safety profile of stage IVB ESCC treated by first-line systemic therapy combined with or without radiotherapy.

Methods

We retrospectively enrolled 155 patients with metastatic ESCC who were treated with first-line systemic therapy including chemotherapy plus anti-PD-1 combined with or without radiotherapy of primary tumor. Propensity score matching (PSM) was performed to minimize the effects of confounding factors. Kaplan-Meier analysis and the log-rank test were conducted to analyze the survival. Prognostic factors were identified by univariate and multivariate cox regression analyses.

Results

The median follow-up period was 22.1 (interquartile range [IQR]: 17.5-27.7) months in the whole cohort. OS and PFS were significantly longer in additional RT group (P = 0.017 for OS, P = 0.04 for PFS). One hundred and twenty-four patients were enrolled after PSM. Additional RT group has superior OS compared to no RT group (P = 0.026). Additional RT group has higher 1-year OS and PFS rates compared to no RT group (1-year OS: 74% vs 52.4%, P = 0.027; 1-year PFS: 61.4% vs 44%, P = 0.046). Multivariate analyses suggested that RT was an independent prognostic factor for OS (hazard ratio [HR]:0.52, 95 % confidence interval [CI]: 0.3-0.91, P = 0.022) and tumor length was an independent predictor for unfavorable PFS (HR: 1.9, 95% CI: 1.06-3.38, P = 0.03). Grade 3-4 lymphocytopenia (83.5% versus 11.1%, P < 0.001) and grade 3-4 esophagitis (21.5% versus 6.7%, P = 0.031) were more frequently observed in additional RT group. Regarding fistula, no significant difference was found between two groups (13.3% versus 8.9%, P =0.544).

Conclusions

Radiotherapy combined with first-line systemic therapy including chemotherapy plus anti-PD1 has superior survival and tolerable toxicities compared to systemic therapy alone for stage IVB ESCC.

Clinical trial identification

Editorial acknowledgement

Legal entity responsible for the study

Sun Yat-sen University Cancer Center.

Funding

Has not received any funding.

Disclosure

All authors have declared no conflicts of interest.