50%) is by far the most common cause of ectopic ACTH, followed by thymic carcinoid (15%), islet cell tumors (10%), bronchial carcinoid (10%), other carcinoids (5%), and pheochromocytomas (2%)"Paraneoplastic Syndromes Caused by Ectopic Hormone ProductionParaneoplastic syndrome CommonEctopic HormoneTypical Tumor TypesHypercalcemia of malignancyParathyroid hormone-related protein (PTHrP)1,25 dihydroxyvitamin DParathyroid hormone (PTH) (rare) Prostaglandin E2 (PGE2)(rare)Squamous cell (head and neck, lung, skin),breast, genitourinary, gastrointestinalLymphomasLung, ovaryRenal, lungSyndrome of inappropriate antidiuretic hormonesecretion (SLADH)VasopressinLung (squamous, small cell), gastrointestinal, genitourinary, ovaryCushing's syndromeAdrenocorticotropic hormone (ACTH)Lung (small cell, bronchial carcinoid, adenocarcinoma, squamous), thymus, pancreatic islet , medullary thyroid carcinoma Corticotropin-releasing hormone (CRH) (rare)Ectopic expression of gastric inhibitory peptide (GIP), luteinizing hormone (LH)/ human chorionic gonadotropin (hCG), other G protein-coupled receptors (rare)Pancreatic islet, carcinoid, lung, prostateMacronodular adrenal hyperplasiaLess Common Non-islet cell hypoglycemiaInsulin-like growth factor (1GF-II)Mesenchymal tumors, sarcomas, adrenal, hepatic, gastrointestinal, kidney, prostate Insulin (rare)Cervix (small cell carcinoma)Male feminizationhCG"Testis (embryonal, seminomas), germinomas, choriocarcinoma, lung, hepatic, pancreatic isletDiarrhea or intestinal hypermotilityCalcitonin1'Lung, colon, breast, medullary thyroid carcinoma Vasoactive intestinal peptide (VIP)Pancreas, pheochromocytoma, esophagusRare Oncogenic osteomalaciaPhosphatonin [fibroblast growth factor 23 (FGF23)IHemangiopericytomas, osteoblastomas, fibromas, sarcomas, giant cell tumors, prostate, lungAcromegalyGrowth hormone-releasing hormone (GHRH)Growth hormone (GH)Pancreatic islet, bronchial and other carcinoidsLung, pancreatic isletHyperthyroidismThyroid-stimulating hormone (TSH)Hydatidiform mole, embryonal tumors, struma ovariiHypertensionReninJuxtaglomerula tumors, kidney, lung, pancreas, ovaryNOTE:Some important points about lung cancer which must be remembered:Most common variety in worldwideMost common variety in non smokersMost common variety in young patientsMost common variety in femalesArising from scars of lung tissueAdenocarcinomaCancer lung which metastases to opposite side (lung to lung metastasis)Bronchoalveolar variant of adenocarcinomaMost common variant in IndiaLung cancer which cavitatesCentral location Best prognosisMost common variety' of lung ca associated with hypercalcemiaAssociated with Nickel, Chromium, Ether, Mustard gasSquamous cell carcinomaMost common variety associated with paraneoplastic syndromeMost common variety in smokersMost aggressive variantAssociated with HypokalemiaWorst prognosisBest response to chemotherapyBest response to radiotherapyAssociated B/L hilar hymphadenopathyCentral locationOccupational risk of UraniumSmall cell carcinoma">