Bone-Seeking Radionuclides Provide Pain Relief for Prostate Cancer Bone Mets

The use of bone-seeking radionuclides effectively controlled bone pain in men with prostate cancer metastatic to the bone, according to the results of a systematic review. Overall, treatment with radionuclides resulted in pain responses greater than 50% to 60%. 

“Although the included studies in this review are very heterogeneous, the reported results are quite consistent,” wrote researchers led by Joyce M. van Dodewaard-de Jong, of the VU University Medical Centre, Amsterdam, in European Urology. “For patients with castration-resistant prostate cancer suffering from malignant bone pain, treatment with a bone-seeking radiopharmaceutical is a relevant therapeutic option often resulting in significant pain reduction.”

According to the study, bone-seeking radiopharmaceuticals are often used to treat patients with multifocal pain due to osteoblastic metastases. Although prior research has looked at the efficacy of bone-seeking radiopharmaceuticals on bone pain, most include patients with a variety of tumor types. Therefore, van Dodewaard-de Jong and colleagues conducted this analysis to look at the efficacy of these radionuclides specifically in patients with prostate cancer.

They conducted a systematic review for publications that discussed radiopharmaceuticals including: 89-strontium-chloride (⁸⁹Sr), 153-samarium-EDTMP (¹⁵³Sm), 186-rhenium-HEDP (¹⁸⁶Re), 188-rhenium-HEDP (¹⁸⁸Re), and 223-radium-chloride (²²³Ra). The review included 36 articles: 13 randomized and 23 prospective studies.

A pooled estimate of pain response could not be calculated because the studies included used different definitions of pain response.

“Because pain is a subjective symptom, assessment of pain response as an outcome is susceptible to bias. About half of the included studies used standardized questionnaires for pain assessment and established a distinct definition of pain response,” the researchers explained.

They found that pain response for ⁸⁹SR was 50% to 60%, and that slightly higher pain responses-in the 70% range-were noted for the other beta-emitting radionuclides,  ¹⁵³Sm, ¹⁸⁶Re, and ¹⁸⁸Re. Similarly, pain response was between 50% to 60% for repeated administration of ²²³ Ra, with pain responses seemingly related to dosage.

Overall, the researchers wrote that when taking all of the studies into account no correlation was found between the dose administered in the study and the efficacy of the radionuclides. However, they did note that several trials looked at different doses of ¹⁵³Sm and that in these trials the best pain responses were noted in the highest dose groups.

The researchers also evaluated hematologic toxicities associated with the use of radionuclides. Twenty-six of the 36 studies included in the review reported on hematologic toxicity, and more than half of the 26 studies reported no grade 3/4 leukopenia or thrombocytopenia.