Radiation treatment of prostate bone metastases and the biological considerations

This contribution on the biology and management of bone metastases from prostatic cancer is divided into three parts. The first details a study conducted at Stanford University on the prevention of bone metastases in the lumbar spine, in patients in whom the lumbar spine has been irradiated coincidental to the radiation treatment of the paraaortic lymph nodes. The incidence of metastases was significantly reduced in 71 patients in whom the apparently normal lumbar spine was irradiated, as compared to the incidence of metastases in 65 patients who received no lumbar irradiation. The implications of these observations on developing strategies for early, or preemptive, irradiation for bone metastases are discussed. In the second part, the optimum radiation dose and fractionation scheme for the palliation of overt bone metastases is addressed. Drawing largely from the work of Arcangeli et al., a total dose of 40-50 Gy*, fractionated at 2 Gy per day, seems to be the regimen of choice for enduring pain relief for most patients with prostatic metastases to bone. Finally, the recent utilization of strontium-89 in the palliation of advanced bone metastases is addressed. *The Gy is the current international unit of radiation. 1Gy = 100 Rad; 1cGy (centigray) = 1 Rad.