What is paraneoplastic syndrome?

Symptoms not explained by metastasis or hormones, 10-15% of cancers, early manifestation of occult neoplasm, significant illness and lethal, may mimin metastasis. Most common is hypercalcemia, Cushing's, non bacterial thrombotic endocarditis. Most associated are lung and breast cancers and hematologic malignancies. Hypercalcemia most due to PTHrP formation by tumor cells, Cushings due to ectopic ACTH, hypercoagulability possible