Abscopal effect of unirradiated lung nodules following radiotherapy alone in recurrent non-small cell lung cancer: a case report

Abscopal effect is an intriguing phenomenon when tumor regression is observed at nonirradiated region distant from the primary irradiation site. Despite its popularity as a research topic (especially in combination with immunotherapy), seldom was the phenomenon observed when radiotherapy (RT) was the only treatment modality. Here we reported the case of a 67-year-old man with abscopal effect observed in the right lung lesions after RT to the recurrent left lung tumor. The patient was a case of metachronous early-stage squamous cell carcinoma (SqCC) of the head and neck and lung. He was otherwise healthy without any other underlying systemic disease, and had never received any medication or systemic treatment. The patient was diagnosed with early-stage left lower lobe SqCC and received postoperative adjuvant RT alone to the tumor bed. Bilateral lung tumor recurrence was observed after 6 months, and the patient completed RT alone to the left lung lesion. However, tumor regression was observed in the non-targeted right lung lesions. Interestingly, we noticed fluctuation in white blood cell (WBC) count around the course of palliative RT. We hope that this case can help secure physicians’ attention to the systemic effect RT alone can contribute.