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.