Radioisotopes to ease metastatic bone pain

Pain is commonly experienced by people whose cancer has spread to their bones. There are several ways to treat this pain, including the administration of radioisotopes, which are chemical elements that emit radiation and act on the bone to reduce the effects of the cancer. This review looked at the effectiveness of radioisotopes for relieving pain, reducing patients' needs for conventional pain-killers, improvements in quality of life, and increased survival. There is some evidence that radioisotopes may give pain relief over one to six months, but the treatment also seemed to be associated with adverse effects, notably reducing blood cells (leucocytes). When comparing different radioisotopes or different doses of a radioisotope, we identified no conclusive differences.

Authors' conclusions: 

This update adds new evidence on efficacy of radioisotopes versus placebo, 89Sr compared with other radioisotopes, and dose-comparisons of 153Sm and 188Re. There is some evidence indicating that radioisotopes may provide complete reduction in pain over one to six months with no increase in analgesic use, but severe adverse effects (leucocytopenia and thrombocytopenia) are frequent.

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Background: 

This is an update of the review published in Issue 4, 2003. Bone metastasis cause severe pain as well as pathological fractures, hypercalcaemia and spinal cord compression. Treatment strategies currently available to relieve pain from bone metastases include analgesia, radiotherapy, surgery, chemotherapy, hormone therapy, radioisotopes and bisphosphonates.

Objectives: 

To determine efficacy and safety of radioisotopes in patients with bone metastases to improve metastatic pain, decrease number of complications due to bone metastases and improve patient survival.

Search strategy: 

We sought randomised controlled trials (RCTs) in MEDLINE, EMBASE, CENTRAL, and the PaPaS Trials Register up to October 2010.

Selection criteria: 

Studies selected had metastatic bone pain as a major outcome after treatment with a radioisotope, compared with placebo or another radioisotope.

Data collection and analysis: 

We assessed the risk of bias of included studies by their sequence generation, allocation concealment, blinding of study participants, researchers and outcome assessors, and incomplete outcome data. Two review authors extracted data. We performed statistical analysis as an "available case" analysis, and calculated global estimates of effect using a random-effects model. We also performed an intention-to-treat (ITT) sensitivity analysis.

Main results: 

This update includes 15 studies (1146 analyzed participants): four (325 participants) already included and 11 new (821 participants). Only three studies had a low risk of bias. We observed a small benefit of radioisotopes for complete relief (risk ratio (RR) 2.10, 95% CI 1.32 to 3.35; Number needed to treat to benefit (NNT) = 5) and complete/partial relief (RR 1.72, 95% CI 1.13 to 2.63; NNT = 4) in the short and medium term (eight studies, 499 participants). There is no conclusive evidence to demonstrate that radioisotopes modify the use of analgesia with respect to placebo. Leucocytopenia and thrombocytopenia are secondary effects significantly associated with the administration of radioisotopes (RR 5.03; 95% CI 1.35 to 18.70; Number needed to treat to harm (NNH) = 13). Pain flares were not higher in the radioisotopes group (RR 0.74; 95% CI 0.27 to 2.06). There are scarce data of moderate quality when comparing Strontium-89 (89Sr) with Samarium-153 (153Sm), Rhenium-186 (186Re) and Phosphorus-32 (32P). We observed no significant differences between treatments. Similarly, we observed no differences when we compared different doses of 153Sm (0.5 versus 1.0 mCi).