Paraneoplastic syndromes associated with lung cancer Nobuhiro Kanaji, Naoki Watanabe, Nobuyuki Kita, Shuji Bandoh, Akira Tadokoro, Tomoya Ishii, Hiroaki Dobashi, Takuya Matsunaga

Paraneoplastic syndromes are signs or symptoms that occur as a result of organ or tissue damage at locations remote from the site of the primary tumor or metastases. Paraneoplastic syndromes associated with lung cancer can impair various organ functions and include neurologic, endocrine, dermatologic, rheumatologic, hematologic, and ophthalmological syndromes, as well as glomerulopathy and coagulopathy (Trousseau's syndrome). The histological type of lung cancer is generally dependent on the associated syndrome, the two most common of which are humoral hypercalcemia of malignancy in squamous cell carcinoma and the syndrome of inappropriate antidiuretic hormone secretion in small cell lung cancer. The symptoms often precede the diagnosis of the associated lung cancer, especially when the symptoms are neurologic or dermatologic. The proposed mechanisms of paraneoplastic processes include the aberrant release of humoral mediators, such as hormones and hormone-like peptides, cytokines, and antibodies. Treating the underlying cancer is generally the most effective therapy for paraneoplastic syndromes, and treatment soon after symptom onset appears to offer the best potential for symptom improvement. In this article, we review the diagnosis, potential mechanisms, and treatments of a wide variety of paraneoplastic syndromes associated with lung cancer.