Low versus high dose of postoperative radiotherapy for locally advanced esophageal squamous cell carcinoma: a propensity score-matched analysis

Abstract

Objective: This study aimed to investigate the effect of different postoperative radiotherapy doses on the prognosis of patients with esophageal squamous cell carcinoma (ESCC).

Methods: A total of 199 patients (aged 18-75 years) with locally advanced ESCC who underwent esophagectomy and postoperative radiotherapy/chemoradiotherapy at the Fujian Cancer Hospital between July 2008 and January 2018 were included. Based on the postoperative radiotherapy dose, the patients were divided into a low-dose group (50-50.4 Gy; median dose 50 Gy) and a high-dose group (>50.4 Gy; median dose 60 Gy). Neoadjuvant and adjuvant chemotherapy regimens included PF (fluorouracil and cisplatin) and TP (paclitaxel and cisplatin) regimens. Patients were followed-up every 3 months in the first 2 years after surgery, every 6 months for the next 3 years, and then subsequently once a year. The primary endpoints were overall survival (OS) and progression-free survival (PFS) rates. The propensity-score matching (PSM) method was applied to identify a 1:1, well-balanced matched cohort with 33 patients in each group for survival comparison.

Results: Among the 199 patients enrolled in this study, 144 and 55 were in the low-dose and high-dose groups, respectively. Univariate and multivariate analyses showed that pathological N classification, vascular tumor emboli, and postoperative radiotherapy dose were independent prognostic factors for both OS and PFS, all p < 0.05. Before PSM, the OS and the PFS of the low-dose group were significantly longer than those of the high-dose group, both p < 0.05. After PSM, better OS and PFS rates were observed in the low-dose group, both p < 0.05. The results showed that patients with pathological stages N0-2 or N3, negative surgical margins, and no vascular tumor emboli could obtain a significant benefit in both OS and PFS after treatment with a low dose of postoperative radiotherapy (50-50.4 Gy). In the subgroup with positive surgical margins, treatment with a low dose of postoperative radiotherapy offered a non-significant survival benefit compared to treatment with a high dose of postoperative radiotherapy.

Conclusions: Our study revealed that for patients with ESCC, the low-dose group (50-50.4 Gy) had a significantly higher OS and PFS than the high-dose group (>50.4 Gy). It was suggested that 50-50.4 Gy might be the recommended postoperative radiotherapy dose for ESCC patients.

Keywords: esophageal squamous cell carcinoma; postoperative radiotherapy; propensity score matching; radiation dose.

FIGURE 1

Overall survival (OS) and progression‐free survival (PFS) of patients with locally advanced esophageal squamous cell carcinoma who have undergone esophagectomy before propensity score matching. (A) Overall survival. (B) Progression free survival. Low dose: postoperative radiotherapy (50–50.4 Gy). High dose: postoperative radiotherapy (>50.4 Gy).

FIGURE 2

Overall survival (OS) and progression‐free survival (PFS) of patients with locally advanced esophageal squamous cell carcinoma who have undergone esophagectomy after propensity score matching. (A) Overall survival. (B) Progression free survival. Low dose: postoperative radiotherapy (50–50.4 Gy). High dose: postoperative radiotherapy (>50.4 Gy).

FIGURE 3

Subgroup analysis based on pN classification. Overall survival (OS) and progression‐free survival (PFS) in the pN0‐2 subgroup; OS and PFS in the pN3 subgroup. (A,C) OS. (B,D) PFS. Low dose: postoperative radiotherapy (50–50.4 Gy). High dose: postoperative radiotherapy (>50.4 Gy).

FIGURE 4

Subgroup analysis based on vascular tumor emboli. Overall survival (OS) and progression‐free survival (PFS) in the no vascular tumor emboli subgroup; OS and PFS in the vascular tumor emboli subgroup. (A,C) OS. (B,D) PFS. Low dose: postoperative radiotherapy (50–50.4 Gy). High dose: postoperative radiotherapy (>50.4 Gy).

FIGURE 5

Subgroup analysis based on surgical margin status. Overall survival (OS) and progression‐free survival (PFS) in the negative surgical margin subgroup; OS and PFS in the positive surgical margin subgroup. (A,C) OS. (B,D) PFS. Low dose: postoperative radiotherapy (50–50.4 Gy). High dose: postoperative radiotherapy (>50.4 Gy).