Radiation therapy drugs effective in treating bone pain

This review examined the effects of different radiopharmaceuticals in reducing bone pain in advanced prostate cancer. Researchers concluded that radiopharmaceuticals were associated with a significant reduction in bone pain.

When prostate cancer spreads outside of the prostate (also called metastatic prostate cancer), tumors can form in distant parts of the body. The most common site of metastatic prostate cancer is on the bone. Bone tumors can cause significant pain and other complications such as fractures or nerve compression. Bone metastases are particularly common in advanced prostate cancer that is progressing despite standard hormone therapy or chemotherapy.

Radiation therapy is an effective treatment for localized pain due to a single bone metastasis. In cases of widespread pain due to many tumors causing bone to break down or dissolve, radiopharmaceuticals can be considered. Radiopharmaceuticals are a type of radiation therapy that use drugs containing radioactive materials. Some of these include 89-strontium-chloride (89Sr), 153-samarium-EDTMP (153Sm), 186-rhenium-HEDP (186Re), 188-rhenium-HEDP (188Re), and 223-radium-chloride (223Ra). 

The aim of this review was to evaluate the effectiveness of radiopharmaceuticals in reducing bone pain from prostate cancer.

This analysis examined the results of 36 separate studies. Each study involved an average of 84 men with advanced prostate cancer. Most men had progressive cancer no longer responding to hormone therapy. All men underwent treatment for metastatic bone pain with one of the radiopharmaceuticals outlined above. Pain response was compared before and after treatment. Pain response was measured between 4 to 16 weeks after treatment with radiopharmaceuticals.

Average pain response (partial and complete response combined) for 89Sr was 50 to 60%. A slightly higher pain response was observed with 153Sm, 186Re, and 188Re (all had an average pain response of 70%). Repeated use of 223Ra resulted in pain responses of 50 to 60%.

Most studies reported no effect of dosage on treatment effectivity. Three studies, however, found that the best pain response was seen with the highest dosage of 153Sm. Pain response also appeared related to the dosage of 223Ra.

Two studies compared treatment with 89Sr with radiation therapy. One study found no difference in pain response. The second study noted a slight advantage of 89Sr over radiation therapy. A separate study found that combining 153Sm with radiation therapy resulted in more complete pain responses compared to 153Sm alone.

26 of the 36 studies reported disorders of the blood following treatment. Very low levels of different types of white blood cells were observed in 0 to 25% of cases. Reports of serious cases of low platelet count varied from 1% to 21%. 24 of the studies noted an initial, short increase in bone pain after treatment. There were no differences in side effects across the different radiopharmaceuticals. 

Researchers concluded that radiopharmaceuticals are a suitable treatment option to reduce bone pain in advanced prostate cancer. However, more high-quality studies are needed comparing the benefit of different radiopharmaceuticals.