By Wickelgren, I.
Science News , Vol. 135, No. 24
Radioactive drugs ease bone-tumor pain
Radiation-emitting chemicals may provide relief for some cancer patients who suffer continuous, toothache-like pain from tumors that have infiltrated their bone. Two of these experimental treatments show impressive success rates and almost no harmful side effects in people whose breast and prostate cancers have spread to bone, researchers reported in St. Louis this week at a meeting of the Society of Nuclear Medicine.
Cancer patients whose malignancies have spread to bone often fail to respond to standard cancer therapies. Physicians usually try to limit tumor growth -- and the pain that accompanies it -- with external radiation, hormones or chemotherapy, but hormones and chemotherapy may provide no pain relief and external radiation is extremely toxic to normal tissue. Its side effects -- which include bone marrow depression, vomiting, diarrhea and lung inflammation -- are especially damaging in patients who harbor many small, dispersed bone tumors, says nuclear medicine physician Harry R. Maxon of the University of Cincinnati Medical Center.
Radioactive cancer drugs cause little or no harm to the patient because they can be given in small, intravenous doses, which the body concentrates near bone tumors, says Ralph G. Robinson at the University of Kansas Medical Center in Kansas City. Once at the tumor site, the drugs give off therapeutic beta-particle radiation that travels only a short distance and so does not affect tissue beyond the bone, he explains.
Robinson's team recently completed trials of radioactive strontium-89--which chemically mimics calcium -- on 28 prostate and four breast cancer patients. They found the injections relieved pain for two to three months in 85 percent of the patients, confirming results of European and Canadian studies and those from Robinson's initial studies in U.S. patients.
"We also found that optimum treatment dose is probably somewhat higher than that used in large numbers of patients in the past. …