These guidelines have been adopted by the British Nuclear Medicine Society.

Strontium kinetics were investigated in a group of 14 patients receiving 89Sr palliation for metastatic bone disease secondary to prostatic carcinoma. Using 85Sr as a tracer, total body strontium retention R(t) was monitored for a 3 month period following 89Sr administration, and at 90 days was found to vary from 11% to 88% and to correlate closely with the fraction of the skeleton showing scintigraphic evidence of osteoblastic metastatic involvement. Strontium renal plasma clearance varied from 1.6 l/day to 11.6 l/day, and in nine patients was significantly reduced compared with values found in healthy adult men, probably due to increased renal tubular reabsorption associated with the disturbance of calcium homoeostasis. Renal clearance rate was the principal factor determining R(t) for t less than 6 days, and was an important secondary factor at later times. Over the interval 30 days less than t less than 90 days, R(t) was closely fitted by the power law function R(t) = R30 (t/30)-b, with R30 and b showing the close correlation expected from the effect of R(t) on strontium recycling. The correction of the data for this effect to determine the true skeletal release rate is described. Measurement of localized strontium turnover in individual metastatic deposits from whole body profiles and scintigraphic images gave retention curves that typically rose to a plateau by 10 days after therapy, and then decreased very slowly. In contrast, retention curves for adjacent normal trabecular bone showed more rapid turnover, peaking at 1 day and subsequently decreasing following a t-0.2 power law function.(ABSTRACT TRUNCATED AT 250 WORDS)

No abstract

In a multi-centre study strontium-89 was shown to be effective in relieving bone pain from prostatic carcinoma in patients who had failed conventional therapies. Of 83 patients assessed at 3 months, following the administration of a dose of at least 1.5 MBq/kg, 75% derived benefit and 22% became pain free. Symptomatic improvement usually occurred within 6 weeks and continued for between 4 and 15 months (mean 6 months). Based on the dose estimation part of this study the recommended dose of strontium-89 is 150 MBq. Toxicity was low, provided platelet levels were above 100 x 10(9) l-1 at the time of treatment. Repeat treatments with strontium-89 may be given at intervals of not less than 3 months. Strontium-89 is administered intravenously on an out-patient basis with no special radiological protection precautions.

The effect of induction therapy with multiple doses of rituximab on the subsequent efficacy and toxicity of anti-CD20 radioimmunotherapy is unknown. We evaluated a novel protocol using 4 weekly infusions of 375 mg/m 2 rituximab followed by 2 fractions of 131 I-rituximab, preceded by a 100-mg/m 2 predose of rituximab, in relapsed indolent B-cell lymphoma. Induction therapy with rituximab significantly increased the effective half-life of 131 I-rituximab (P ‫؍‬ .003) and high serum levels of rituximab after induction therapy correlated with increased effective half-life of the radioimmunoconjugate (P ‫؍‬ .009). Patients with large tumor burdens experienced significant increases in the effective half-life of 131 I-rituximab between delivery of the first and second fractions (P ‫؍‬ .007). Induction therapy with multiple doses of rituximab did not appear to compromise the clinical efficacy or increase toxicity of subsequent 131 I-rituximab radioimmunotherapy. The overall response rate was 94%, with complete response rate 50%.The median time to progression was 20 months, significantly longer than for the last qualifying chemotherapy (P ‫؍‬ .001). Fractionation of 131 I-rituximab allowed cumulative whole-body doses of more than 120 cGy, approximately 60% greater than those previously achieved with a single administration of a murine radioimmunconjugate, to be delivered without significant hematologic toxicity.