Parathyroid, cancer

The delicate balance maintained by these factors is altered in patients with cancer by two principal mechanisms tumor production of humoral factors that alter calcium metabolism (humoral hypercalcemia) and local osteolytic activity from bone metastases.27 Humoral hypercalcemia causes around 80% of all hypercalcemia cases and is mediated primarily by systemic secretion of parathyroid hormone-related protein... 

Gy Whole body Single brief exposure Linear dose relation to thyroid cancer, and pathology in adjacent parathyroid and salivary glands 16... 

No excess of cancer was reported in two follow-up smdies of affected individuals in Turkey about 20-30 years after consumption of contaminated grain had ceased. " In mice, liver tumors were observed after exposure to HCB at 12-24mg/kg/day in the diet, but not at 6mg/kg/day. Hepatomas, hepatocellular carcinomas, bile duct adenomas, and renal cell adenomas were observed in rats after dietary administration." Liver tumors were also observed in 100% of surviving females and 16% of males after dietary administration to rats for 90 weeks. In another study, increased incidence of parathyroid adenomas and adrenal pheochromocytomas were observed in male and female rats and liver neoplastic nodules in females of the Ei generation in a two-generation feeding study. 

Levothyroxine is taken orally or intravenously and is normally prescribed to treat hypothyroidism or to suppress the release of thyroid hormone so as to manage cancerous thyroid nodules (i.e., thyroid cancer) and growth of goiters. Other less frequently prescribed thyroid and parathyroid drugs include methimazole (Tapazole), various iodides, lithioronine (Triostat), and liotrix (Thyrolar). 

The receptor for l,25(OH)2D exists in a wide variety of tissues—not just bone, gut, and kidney. In these "nonclassic" tissues, l,25(OH)2D exerts a number of actions including regulation of parathyroid hormone secretion from the parathyroid gland, insulin secretion from the pancreas, cytokine production by macrophages and T cells, and proliferation and differentiation of a large number of cells, including cancer cells. Thus, the clinical utility of l,25(OH)2D and its... 

About 40 small protein or peptide drugs are currently in clinical use with an estimated annual market of US 1 billion. These include insulin, parathyroid hormone (PTH), calcitonin, growth hormones, and so on [127], In oncology, several antibodies directed against surface proteins have entered the market over the last years, including herceptin in breast cancer, cetux-imab in CRC, imatinib in gastrointestinal stromal tumors, and so on. 

Rabbani, S. A., Gladu, J., Harakidas, R, Jamison, B. and Goltzman, D. (1999). Over-production of parathyroid hormone-related peptide results in increased osteolytic skeletal metastasis by prostate cancer cells in vivo. Inti. J. Cancer 80, 257-264. 

Hypercalcemia occurs with hyperparathyroidism, a disease involving the excessive production of PTH by the parathyroid gland. Hypercalcemia can result from cancers that produce l,25-(OH)jDg, Cancer cells produce a variety of other molecules that stimulate osteoclasts this condition is called oncogenic hypercalcemia. 

A patient with androgen-independent prostate cancer developed hypocalcemia during treatment with estramustine (12). The total serum calcium concentrations before and after the initiation of estramustine were 2.1 and 1.1 mmol/1 respectively. This prompted a retrospective survey of hjrpocalcemia in 135 consecutive patients taking estramustine 20% were affected. The authors speculated that estramustine may cause hjrpocalcemia by inhibiting mobilization of calcium and the action of parathyroid hormone on the skeleton. 

Parathyroid Hormone-Related Protein PTHrP was discovered in 1987 by investigators studying the mechanism by which certain cancers produce humoral hypercalcemia of malignancy (HHM). ... 

Burtis WJ, Brady TG, Orlofif JJ, Ersbale JB, WarreU RP Jr, Olson BR, et al. Immunochemical characterization of circulating parathyroid hormone-related protein in patients with humoral hypercalcemia of cancer. 

Ralston SH> Danks J, Hayman J, Fraser WD, Stewart CS, Martin TJ. Parathyroid hormone-related protein of malignancy immunohistochemical and biochemical studies in normal and hypercalcemic patients with cancer. J Clin Pathol 1991 44 472-6. 

A second member of the parathyroid hormone family, parathyroid hormone-related protein (PTHrP), is quite similar to PTH in amino acid sequence and protein structure. Like PTH, it activates the parathyroid hormone receptor causing increased bone resorption and renal tubular calcium reabsorption. Increased serum concentrations of parathyroid hormone-related protein are the predominant cause of hypercalcemia in cancer patients with solid tumors. This observation led to its discovery and to the elucidation of its many cellular functions in normal tissues. In contrast to PTH, which is expressed only in parathyroid glands, PTHrP is detected in many tissues in fetuses and adults it is found in epithelia, mesenchymal tissues, endocrine glands, and the central nervous system. This protein is also the principal regulator of placental calcium transport to the fetus. 

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