Recurrent and Metastatic Small Cell Carcinoma of the Esophagus in Which Long-Term Survival Was Achieved by Abscopal Effect of Radiotherapy: A Case Report.

Introduction: Small cell carcinoma of the esophagus (SCCE) is an uncommon tumor characterized by frequent recurrence, metastasis, and dismal prognosis. Due to its rare nature, optimal treatment is extremely scarce and randomized studies are not available and are unlikely to be conducted. It has been recognized that high-dose fractionated radiotherapy combined with immunotherapy can induce abscopal effect, which is termed and observed as an immune response leading to an antitumoral effect also distant from the irradiated area in patients undergoing radiotherapy and finally will shed new light on the treatment of this rare tumor. Case Presentation: We report a male patient with SCCE. Despite aggressive management including surgery and salvage therapies, the patient experienced multiple recurrences within the first 2 years postoperatively. However, through vigilant surveillance facilitating early recurrence detection and prompt intervention - notably stereotactic body radiotherapy (SBRT) combined with immunotherapy - a potential abscopal effect was observed. Remarkably, the patient achieved a durable complete remission and long-term survival, remaining alive with minimal complications at 61 months post-diagnosis and continuing follow-up. Conclusion: The exceptional long-term progression-free survival of 61 months achieved in this SCCE patient may be attributed to the abscopal effect, hypothesized to have been induced by the synergistic combination of SBRT and immunotherapy.