[Cancer and electrolytes imbalance]

The electrolyte imbalance in advanced cancer patients, including hyperkalemia, hypercalcemia and hyponatremia, can be induced by various factors. Hyperkalemia is occasionally induced by chemotherapy for very large malignant tumors, due to tumor lysis syndrome. Hypercalcemia and hyponatremia are often observed in patients with breast cancer, renal cancer, prostate cancer, and the like, as a paraneoplastic syndrome. Some part of hypercalcemia results from osteolysis, but the majority is induced by hormonal factors, such as parathyroid hormone-related protein. One of the paraneoplastic causes of hyponatremia is antidiuretic hormone-producing tumor. These disorders could be morbid or even motile, resulting from encephalopathy or arrhythmia in some cases. However, it should be kept in mind that they could be improved or cured by prompt treatment. Recently, after approval of the molecular targeted drugs for epidermal growth factor receptors, such as cetuximab and panitumumab, the incidence of hypomagnesia with use of these monoclonal antibodies, is relatively frequent. In addition, small molecular targeted drugs, such as m-TORinhibitors and ABL kinase inhibitors, also exert adverse reactions including hypomagnesia and hypophosphatemia. Careful monitoring of the serum concentration of magnesium and phosphate ions, to which little attention was paid previously, is a key issue in these cases.