Long-Term Outcomes of Three-Dimensional Conformal Radiation Therapy Without Chemotherapy for Esophageal Squamous Cell Carcinoma: A Final Report of a Phase 2 Study

Abstract

Chemo-radiotherapy is the standard treatment for locally advanced inoperative patients, but will increase the acute toxicity significantly, which could not be tolerated by most of Chinese. We conducted a prospective study previously to determine the tolerability of and the survival rate using three-dimensional conformal radiotherapy (3-DCRT) without chemotherapy for esophageal squamous cell carcinoma (SCC). Here, we report the long-term outcomes in this clinical trial, including survival data. Patient eligibility criteria were: (1) histologically or cytologically proven esophageal SCC; (2) age 18–80 years; (3) Karnofsky performance status (KPS) ≥ 70; (4) clinical stages of I–IVA (AJCC, 2002) with disease unresectable or inoperable, or the refusal of surgery; (5) no chemotherapy or surgery before enrollment; (6) normal liver, kidney and bone marrow functions; (7) no previous cancer history; and (8) informed consent. PTV1 composed of a 1.2–1.5 cm margin lateral around GTV and 3.0 cm margin superior/inferior of GTV. PTV2 encompassed GTV with a margin of 0.5–0.7 cm. The dose for PTV1 was 50 Gy in 2 Gy daily fractions; PTV2 received a boost of 16 Gy in 2 Gy daily fractions to a total dose of 66 Gy. No chemotherapy was given. Thirty patients underwent 3-DCRT for thoracic esophageal SCC. Among them, 13 patients were stage IIA or IIB, 15 stage III, and 2 stage VIA. The median follow-up time was 30 months for all patients and 75 months for patients alive at the last follow-up examination. The median overall survival was 30 months, and the 2-year, 3-year, 5-year overall survival rates were 58.6%, 41.4%, and 31.0%, respectively. The 1-year, 2-year, and 5-year local-regional control rates were 65%, 42.2%, and 36.1%, respectively, and the 1-year, 2-year and 5-year distant metastasis rates were 19.9%, 34.1%, and 34.1% respectively. Twenty-eight patients (93.3%) had either no toxicity (21/30, 70.0%) or grade 1 (7/30, 23.3%) late lung toxicity. We concluded that high dose of 66 Gy delivered by 3-DCRT was well tolerated with minor toxicities. Five-year overall survival rate of 31% without chemotherapy in this group patients were encouraging.