Background and aim: The aim of this study was to clarify the efficacy and limitations of radiation therapy (RT) for superficial esophageal carcinoma, and to explore the indications for more aggressive therapy, such as combined chemo-radiotherapy.
Methods: Sixty-eight patients with stage I (UICC T1N0M0) esophageal squamous cell carcinoma treated by definitive RT alone were analyzed. Brachytherapy was administered in 36 patients as a boost, and the prescribed doses were 10 Gy (5 Gy x 2 times) at a low dose rate (19 patients) and 9 Gy (3 Gy x 3 times) at a high dose rate (17 patients). Recurrence patterns and survival rates were assessed and the factors predisposing to recurrences after RT were statistically investigated by univariate analysis.
Results: The 5-year cause-specific survival rate and the locoregional control rate were 79.9% and 82.1%, respectively. No case of recurrence or disease-related death was observed in any of the patients with mucosal cancer. Among the cases with the cancer invading the submucosa, there were 12 cases with locoregional recurrence and two cases with distant metastases. In cases of submucosal esophageal cancer, the tumor length was the only statistically significant factor predicting locoregional control. The 5-year locoregional control rate in cases with a short length of the tumor (<or=5 cm) was 83.3%, whereas the corresponding rate in cases with the tumor measuring >5 cm in length was 57.8% (P = 0.036). Patients treated by additional brachytherapy exhibited better cause-specific survival and locoregional control rates than those receiving external RT alone, however, the addition had no statistically significant influence on the outcome.
Conclusions: RT was a successful treatment for stage I esophageal cancer, and the treatment outcome using RT was nearly comparable to that of surgery. However, it is suggested that chemo-radiation should be considered in inoperable cases of submucosal cancer when the tumor is more than 5 cm in length.