89Sr radionuclide therapy: Dosimetry and haematological toxicity in two patients with metastasising prostatic carcinoma

Abstract

We present dosimetry for spinal metastases and red bone marrow in two patients who received 89Sr therapy for disseminated prostatic carcinoma. Absorbed dose to metastases was estimated by combining 85Sr gamma camera studies with computed tomographic measurements of bone mass, and doses of 20 cGy/MBq and 24 cGy/MBq were found for vertebral metastases that uniformly involved the bodies of L3 and D12 respectively. Absorbed dose to red bone marrow was estimated from total body strontium retention studies using the ICRP model for bone dosimetry, and a ratio of metastatic to marrow dose of around 10 was found in each patient. Although they received comparable treatment activities of around 200 MBq, the patients showed markedly different haematological response, this difference being confirmed when each received a second 89Sr treatment 6 months after the first. As a result, clinically significant thrombocytopenia occurred in one patient which prevented further radiostrontium therapy being given.

Palliation and Survival After Repeated 188Re-HEDP Therapy of Hormone-Refractory Bone Metastases of Prostate Cancer: A Retrospective Analysis

“…89 Sr-chloride and ionic 90 Y are both calcium analogs that are sequestered as cations by bone in relation to the intensity of osseous metabolism (5)(6)(7)(8)(9). 89 Sr is excreted renally to 70%-90% and is eliminated from the vascular compartment within the first few hours (10). Except for bone uptake and excretion via the urinary system, there is no accumulation in any organ system.…”

Internal Radiation Dosimetry: Models and Applications

“…It is naturally taken up in bone and is a pure β -emitter with a long half-life (50.53 days). Pharmacokinetic and dosimetry studies have been based on imaging of 85 Sr-Cl (Blake, 1986(Blake, , 1987(Blake, , 1998Breen, 1992), although imaging based on bremsstrahlung photons from 89 Sr has also been performed (ICRP, 1997). Tumour dosimetry is generally performed under the assumption that the activity uptake is five times higher than for normal bone.…”

12 Chapters on Nuclear Medicine

“…The majority of bone metastases from prostate cancer are sclerotic whilst metastases of breast cancer generally are mixed osteolytic/sclerotic. Also patients with bone metastases from tumours other than prostate and breast cancer and increased 99m Tc-MDP uptake on bone scan can benefit from targeted radionuclide therapy (Leondi, 2004;Minutoli, 2006 (Blake, 1986(Blake, , 1987(Blake, , 1998Breen, 1992), although imaging based on bremsstrahlung photons from 89 Sr has also been performed (ICRP, 1997). Tumour dosimetry is generally performed under the assumption that the activity uptake is five times higher than for normal bone.…”