[Obstructive sleep apnea syndrome in a patient with superior vena cava syndrome caused by lung cancer].

A 48-year-old man was treated with chemotherapy and irradiation therapy for superior vena cava syndrome (SVCS) caused by adenocarcinoma of the lung, and his symptoms subsided temporarily. However, the same symptoms recurred, and severe snoring during sleep and daytime hypersomnolence developed. Obstructive sleep apnea syndrome (OSAS) was diagnosed by respiratory inductive plethysmography. After chemotherapy, the symptoms of edema of the face and arms, snoring, and daytime somnolence tendency were alleviated, and the patient's apnea hypopnea index decreased remarkably. In addition, lateral cephalograms disclosed improved patency of the upper respiratory tract and dilation of the soft palate. These findings suggested a relationship between SVCS and OSAS. OSAS may cause a deterioration of circulatory dynamics and the quality of life when it develops secondary to SVCS. Therefore, it is necessary to determine whether OSAS is present and accordingly provide suitable treatment in patients with SVCS.