ESTRO 2024 - Abstract Book

S2161

Clinical - Upper GI

ESTRO 2024

Definitive-dose radiotherapy post endoscopic submucosal dissection for superficial esophageal cancer

Yuki Wada, Satoshi Kumagai, Noriko Takagi, Tetsugaku Shinozaki, Toshiki Murata, Daichi Sugawara, Naoko Mori

Akita University Graduate School of Medicine, Radiology, Akita, Japan

Purpose/Objective:

Endoscopic submucosal dissection (ESD) is a minimally invasive therapy for superficial esophageal cancer. However, if pathological findings indicate a tumor invading the muscularis mucosa (MM) with lymphovascular invasion (LVI) or submucosa (SM), adjuvant therapy is required because of the high risk of potential locoregional lymph node metastases. A multicenter prospective study in Japan reported that prophylactic chemoradiation therapy (CRT) using approximately 40 Gy post-ESD yielded favorable outcomes, but it could not sufficiently prevent locoregional lymph node metastases [1,2]. We retrospectively analyzed the outcomes and adverse events of our treatment regimen with definitive-dose radiation therapy (RT) of approximately 50 – 60 Gy, with or without chemotherapy, for these patient populations. Additionally, we analyzed the predictive factors for progression-free survival (PFS) and overall survival (OS).

Material/Methods:

Between 2006 and 2018, 52 consecutive patients underwent RT/CRT after EST at our institution. Seven patients were excluded for various reasons, including incomplete margin-free resection by ESD (two patients), rare histological type with small cells or basaloid (two patients), concurrent double cancer of the pancreas (one patient), histological depth deeper than the SM (one patient), and a history of mediastinal lymph node dissection for another cancer (one patient). Ultimately, 45 consecutive patients (43 men and 2 women; median age, 70 years; range, 52 – 83 years) underwent RT/CRT with a definitive dose after ESD, and they exhibited a pathological depth of MM with LVI or SM. Approximately 40 Gy of RT was delivered prophylactically, including the locoregional lymph node area of the esophagus from the two anterior-posterior opposing fields, followed by 10 – 20 Gy boost radiation to the entire esophagus or primary tumor site from two oblique opposing fields to avoid spinal cord injury. If feasible, systemic chemotherapy with 5-fluorouracil plus high- or low-dose cisplatin or nedaplatin was administered concurrently for up to two cycles. Adverse events were evaluated according to the Common Terminology Criteria for Adverse Events (version 5.0). PFS, OS, and prognostic factors were analyzed using the Kaplan – Meier method and Cox proportional hazard models.

Results:

The median observation period was 74 months (range, 4 – 174 months). All the histological types were squamous cell carcinomas. The pathological depth was MM in 14 (31%) and 31 (69%) patients, respectively. Thirty-two (71%) patients had LVI. Chemotherapy was administered to 34 (76%) patients.