Lung cancer is the leading cause of cancer-related mortality worldwide. The treatment of advanced lung cancer is improving with the development of new treatments like immune checkpoint inhibitors (ICIs) and various molecular targeted agents, which have extended overall survival (OS). However, complete remissions remain rare. The efficacy of chemotherapy is modest, which makes a complete sustained response very unlikely, especially when compared with more recent options.In this article, we report a stage IV non-small-cell lung cancer (SCLC) that achieved a complete response in 2018 with chemotherapy (cisplatin and paclitaxel) after pembrolizumab and after the patient had received radiotherapy for superior vena cava syndrome (SVCS). The patient remains in complete response as of October 2022. We hypothesized that the overlap between circulating anti-PD-1, radiotherapy, and cytotoxic agents could explain this outcome.

Opsoclonus-myoclonus syndrome (OMS), also known as Kinsbourne syndrome or dancing eyes syndrome, is an extremely rare neurological condition that comprises a heterogenous constellation of symptoms including opsoclonus along with diffuse or focal body myoclonus. It is usually referred to as a paraneoplastic entity, but it may also be associated to an infectious, metabolic, or idiopathic cause. Small-cell carcinoma of the lung is the most commonly reported malignancy associated with OMS. The authors describe a case of a 69-year-old male that presented with ataxic gait, phono-and photophobia, vertigo, dizziness, lethargy, nausea, and vomiting. During examination, rapid, multidirectional eye movements; slight dysarthria; and facial myoclonus were noted. He was admitted to the hospital, and after a thorough study, a diagnosis of OMS was established. Intravenous corticosteroids were started, alongside physiotherapy, and a slight improvement of his symptoms was noted. Imaging revealed a suspicious lesion in the left lung, along with lymphadenopathies and bone metastases. Histology confirmed the diagnosis of stage IV small-cell lung cancer (SCLC). Chemotherapy (ChT) with carboplatin and etoposide was started, and a gradual improvement of his neurological complaints was noted. After six cycles, the disease progressed, and secondline ChT with topotecan was started. After two cycles, the patient experienced significant clinical deterioration and eventually died. In conclusion, OMS is a poorly understood condition with uncertain neurological prognosis. The treatment of the primary neoplasm may improve neurological symptoms. The recognition of paraneoplastic syndromes is of utmost importance since early diagnosis of a malignancy relates to better outcomes.