Radioisotope therapy in bone and joint disease

The short range tissue destruction of beta-emitting radioisotopes can be utilized in painful metastatic disease of the skeleton by employing a radionuclide that is specifically metabolized in or adjacent to these lesions. Sodium phosphate P 32 has been used for this purpose for the past 25 yr. It uptake in skeletal tumor and in osteoblastic new bone adjacent to tumor can be markedly increased by pharmacologic stimulation using androgenic steroids, or during rebound deposition after a course of parathyroid hormone. Although efficacy in terms of subjective pain relief is high, more objective signs of success are often lacking, and survival, while more confortable, is not prolonged. Marrow depression is the most significant side effect. A beta-emitting, bone-seeking isotope, 89Sr, may have a better therapeutic/toxic ratio, and should receive further trial. Radiation-induced necrosis has also been applied, though more hesitantly, to the proliferative, destructive, but nonmalignant synovium in rheumatoid disease. Here, a number of colloidal preparations, most commonly 198Au, have been employed. Again, relief of symptoms, particularly recurrent joint effusions, is quite high, although the basic disease process is not reversed. The major hazard here appears to be leakage of material to regional lymph nodes, resulting in irradiation of circulating lymphocytes. Although chromosomal damage can be detected when such cells are then cultured, the actual consequences of this, if any, are not presently known. Both shorter-lived (165Dy) and longer-lived (32P) larger-size colloids are being evaluated, which may prove safer in this regard than 198Au.