Relative efficacy of 32P and 89Sr in palliation in skeletal metastases

32p and 89Sr have been shown to produce significant pain relief in patients with skeletal metastases from advanced cancer. Clinically significant pancytopenia has not been reported in doses up to 12 mCi (444 MBq) of either radionuclide. To date, no reports comparing the relative efficacy and toxicity of the two radionuclides in comparable patient populations have been available. Although a cure has not been reported, both treatments have achieved substantial pain relief. However, several studies have used semiquantitative measures such as "slight," "fair," "partial" and "dramatic" responses, which lend themselves to subjective bias. This report examines the responses to treatment with 32P or 89Sr by attempting a quantification of pain relief and quality of life using the patients as their own controls and compares toxicity in terms of hematological parameters.

Thirty-one patients with skeletal metastases were treated for pain relief with either 32P (16 patients) or 89Sr (15 patients). Inclusion criteria were pain from bone scan-positive sites above a subjective score of 5 of 10 despite analgesic therapy with narcotic or non-narcotic medication, limitation of movement related to the performance of routine daily activity and a predicted life expectancy of at least 4 mo. The patients had not had chemotherapy or radiotherapy during the previous 6 wk and had normal serum creatinine, white cell and platelet counts. 32P was given orally as a 12 mCi dose, and 89Sr was given intravenously as a 4 mCi (148 MBq) dose. The patients were monitored for 4 mo.

Complete absence of pain was seen in 7 of 16 patients who were given 32P and in 7 of 15 patients who were given 89Sr. Pain scores fell by at least 50% of the pretreatment score in 14 of 16 patients who were given 32P and 14 of 15 patients who were given 89Sr. Mean duration of pain relief was 9.6 wk with 32P and 10 wk with 89Sr. Analgesic scores fell along with the drop in pain scores. A fall in total white cell, absolute granulocyte and platelet counts occurred in all patients. Subnormal values of white cells and platelets were seen in 5 and 7 patients, respectively, with 32P, and in 0 and 4 patients, respectively, after 89Sr therapy. The decrease in platelet count (but not absolute granulocyte count) was statistically significant when 32P patients were compared with 89Sr patients. However, in no instance did the fall in blood counts require treatment. Absolute granulocyte counts did not fall below 1000 in any patient. There was no significant difference between the two treatments in terms of either efficacy or toxicity.

No justification has been found in this study for the recommendation of 89Sr over the considerably less expensive oral 32P for the palliation of skeletal pain from metastases of advanced cancer.