Optimal radiation dose for esophageal squamous cell carcinoma

Objective: To analyze the survival of patients with esophageal squamous cell carcinoma (ESCC) treated by different regimens and different radiation doses and to explore the optimal radiation dose and subgroups with potential clinical benefit. Methods: A total of 1387 patients with ESCC who received conformal radiotherapy or intensity-modulated radiotherapy in our hospital from July 2003 to March 2014 were enrolled in this retrospective study. The patients who received different radiation doses in radiotherapy alone or in concurrent chemoradiotherapy were analyzed. The log-rank test and Cox regression analysis were used to explore the optimal radiation dose and the benefited subgroups. Results: A total of 780 patients only received radiotherapy. Among them, the median survival of patients receiving radiation dose < 60 Gy (n = 91), 60 Gy (n = 429), and > 60 Gy (n = 260) was 9, 20, and 23 months, respectively, suggesting a significant difference (P = 0.000). The patients with a radiation dose of 60 Gy had a similar survival curve to the patients with radiation dose > 60 Gy, both significantly higher than that in patients with radiation dose < 60 Gy (P = 0.000, 0.000). Totally 302 patients received concurrent chemoradiotherapy. Among them,the median survival of patients receiving radiation dose < 60 Gy (n = 18), 60 Gy (n = 224), and > 60 Gy (n = 60) was 22, 34, and 15 months, respectively, suggesting a significant difference (P = 0.004). The survival curve showed no significant difference between the patients with radiation dose < 60 Gy and > 60 Gy (P = 0.952), while the patients with a radiation dose of 60 Gy had a better survival compared with the patients with radiation dose < 60 Gy or > 60 Gy. The Cox multivariate regression analysis indicated that the ESCC patients receiving radiotherapy alone or concurrent chemoradiotherapy had different prognosis; gross tumor volume (GTV) and radiation dose were two independent prognostic factors in the same treatment model (P = 0.045, 0.001). In radiotherapy alone, radiation dose ≥60 Gy was a protective factor for the patients' survival (P = 0.000). In concurrent chemoradiotherapy, a radiation dose of 60 Gy was a protective factor, while radiation dose < 60 Gy or > 60 Gy presented no survival benefit (P = 0.051). Conclusions: The optimal radiation dose is no less than 60 Gy in ESCC patients treated by radiotherapy alone. If the patients receive concurrent chemoradiotherapy, the radiation dose of 60 Gy is recommended. (authors)