Paraneoplastic syndromes in digestive tumors: a review

Paraneoplastic syndromes are disorders induced by the altered immune response to a malignant tumor, which secretes hormones, peptides, or cytokines. The clinical manifestations of the paraneoplastic syndromes are the consequence of the substances produced by the tumor and may affect various organs and systems, being classified in endocrine, neurologic, dermatologic, rheumatologic and hematologic syndromes. These syndromes are most commonly associated with malignancies like small cell lung cancer, breast cancer, gynecologic tumors and hematologic malignancies. Paraneoplastic syndromes may be the first or most obvious manifestation of a neoplasia; if they occur in a patient without a known cancer, they should be carefully investigated. In this regard, they may reveal early a clinically ocult tumor, in a highly treatable stage. The incidence and prevalence of digestive tumors is increasing. Therefore, in order to ensure proper treatment and longer survival, an early diagnosis is necessary. Gastrointestinal cancers are often accompanied by paraneoplastic syndromes, which sometimes may be the "clue" for the diagnosis of cancer. In digestive malignant neoplasms, paraneoplastic dermatologic syndromes are the most common. The evolution of patients with paraneoplastic syndromes depends on patient's comorbidities and complications. If the malignancy is successfully treated, the paraneoplastic syndromes will evolve favorably.