Abscopal Effect After Palliative Radiotherapy in a Patient with a Gastric Adenocarcinoma Disseminated to Retroperitoneal Space: Case Report from a Latin American Reference Center and Review of the Literature.

Radiation therapy is known to have a highly effective local and regional effect for cancer treatment; however, sporadic events of tumor regression in non-irradiated and irradiated fields have been observed over time, which is known as the "abscopal effect." In this report, we describe the case of a patient with a diagnosis of unresectable advanced gastric adenocarcinoma, who developed extensive retroperitoneal lymph node involvement and did not accept management with chemotherapy. Primary radiotherapy at the local level was offered to control hemostasis, reaching an important span of complete remission of the disease.