Simultaneous integrated boost for mediastinal lymph node recurrence after radical surgery for esophageal cancer: Interim results from a phase I/II prospective study

Background This was a single institute, phase I/II study of salvage chemoradiotherapy (CRT) with simultaneous integrated boost in patients with mediastinal lymph node (LN) recurrence after esophagectomy. Methods Patients who presented with a clinical diagnosis of <= 5 mediastinal LN recurrence received three consecutive levels of radiotherapy dose for the recurrences. Level 1: 58.8 Gy/2.1 Gy/28 fractions, Level 2: 64.4 Gy/2.3 Gy/28 fractions and Level 3: 70 Gy/2.5 Gy/28 fractions. Results A total of 17 patients (10 patients in phase I and 7 patients in phase II) were enrolled in the present study between June 2019 and July 2020. The median duration from surgery to initial recurrence was four months (range: 3-43 months). The most common site of recurrence according to JES was 106recR, accounting for 35%. Dose-limiting toxicity was not observed during three-month follow-up after completion of irradiation. The most common hematological toxicities were leukocytopenia and anemia. The most common nonhematological toxicity was esophagitis. The ORR according to RECIST was 58.8% (CR: seven patients; PR: three patients). With a median follow-up of 15 months (95% CI: 7-16 months), all patients were still alive. Among them, two patients who received a level 1 dose and one patient who received a level III dose developed multiple lung metastases after salvage CRT, and another patient who received a level 1 dose developed an out-of-field recurrence in the left cervical lymph node area. Another patient who received a level III dose developed chest wall recurrence after salvage CRT. Conclusions The regimen of salvage CRT using the simultaneous integrated boost (SIB) technique (70 Gy/2.5 Gy/28F) for mediastinal lymph node recurrence in ESCC patients after esophagectomy is feasible and well tolerated.