Radiotherapy-induced abscopal effect on the metastatic carcinoma of unknown primary origin: a case report and literature review

OBJECTIVE: Abscopal effect of radiotherapy refers to a clinical phenomenon that is characterized by the eradication of distant metastatic tumors following localized irradiation. Reports on the abscopal effect following pure radiotherapy have been relatively rare. CASE REPORT: Herein, we reported a 70-yearold male patient, who has been subjected to swelling and pain in the left neck. Computed tomography examination presented a metastatic lymph node of the left cervical and an intra-abdominal mass which was located in hepatogastric space, upward of the pancreatic head. Histopathology of the left cervical lymph node further ensured a poorly-moderately differentiated form of squamous cell carcinoma. But the primary origin was not defined. This patient received radiotherapy on the metastatic lymph nodes of the left cervical (dose: 60 Gray in 30 fractions) only. After treatment, the pain in the left neck dramatically improved and the swelling of the radiation exposure site diminished gradually. Computed tomography examination also confirmed that the abdominal mass was significantly reduced. CONCLUSIONS: The abscopal effect, in this case, may help us to get a better understanding of the impact of radiotherapy.