Hypercalcemia in malignancies of the female genital tract

Hypercalcemia is the most common paraneoplastic syndrome in adult malignancies (10%-30%) and rare in pediatric cancers (0.5%-1.3%). Hypercalcemia in malignancies is categorized into two groups: 1) Humoral hypercalcemia of malignancy (HHM) - caused by substances that are produced by the tumor cells and secreted into the blood circulation such as parathyroid hormone-related protein (PTH-rP), parathyroid hormone-intact (PTH-i), the enzyme 1-a-hydroxylase that catalyzes the synthesis of the active form of vitamin D (1,25-dihydroxyvitamin D3), and other substances. 2) Hypercalcemia due to bone destruction by metastases. Hypercalcemia occurs in less than 5% of female genital tract malignancies and virtually in all cases (95%) it is HHM. Female genital tract malignancy-associated HHM is caused most often (80%) by PTH-rP. Ovarian cancer is the most common female genital tract malignancy that is associated with HHM. Although HHM occurs in only 5% of ovarian cancers, it occurs in a relatively high percentage in the following rare ovarian tumors: a). Small cell carcinoma of the ovary - a rare tumor that accounts for only 1% of all ovarian cancers and is associated with HHM in 66% of the cases b). Clear cell carcinoma of the ovary - an uncommon tumor that accounts for 5% of all ovarian cancers and is associated with HHM in 5%-10% of the cases. Since dysgerminoma is the most common malignant ovarian tumor in children, in girls it is the second most common ovarian neoplasm, after ovarian small cell carcinoma, to be associated with HHM.