Strontium-89 chloride in the treatment of bone metastases from breast cancer

Bone Metastases: Mechanisms of the Metastatic Process, Imaging and Therapy

The mechanisms by which tumors metastasize to bone are complex. Upon the successful establishment of metastatic deposits in the skeleton, detection of the disease becomes essential for therapeutic planning. The roles of CT, skeletal scintigraphy, SPECT/CT, MRI, PET/CT and PET/MRI will be reviewed. Therapeutic response criteria specifically designed to evaluate bone metastases (MD Anderson/MDA criteria) can guide image interpretation. Knowledge of therapeutic strategies such as systemic therapy with bisphosphonates or radiopharmaceuticals, radiation therapy, surgery, and percutaneous interventions such as vertebroplasty and radiofrequency ablation can help the radiologist produce reports that will provide maximum benefit to clinicians and patients.

A One-Pot Three-Component Double-Click Method for Synthesis of [67Cu]-Labeled Biomolecular Radiotherapeutics

A one-pot three-component double-click process for preparing tumor-targeting agents for cancer radiotherapy is described here. By utilizing DOTA (or NOTA) containing tetrazines and the TCO-substituted aldehyde, the two click reactions, the tetrazine ligation (an inverse electron-demand Diels-Alder cycloaddition) and the RIKEN click (a rapid 6π-azaelectrocyclization), could simultaneously proceed under mild conditions to afford covalent attachment of the metal chelator DOTA or NOTA to biomolecules such as to albumin and anti-IGSF4 antibody without altering their activities. Subsequently, radiolabeling of DOTA- or NOTA-attached albumin and anti-IGSF4 antibody (an anti-tumor-targeting antibody) with [⁶⁷Cu], a β⁻-emitting radionuclide, could be achieved in a highly efficient manner via a simple chelation with DOTA proving to be a more superior chelator than NOTA. Our work provides a new and operationally simple method for introducing the [⁶⁷Cu] isotope even in large quantities to biomolecules, thereby representing an important process for preparations of clinically relevant tumor-targeting agents for radiotherapy.

Radiopharmaceuticals for bone metastasis therapy and beyond: a voyage from the past to the present and a look to the future

Bone cancer can be divided into primary and secondary (metastatic) bone cancer. Osteosarcoma is the most common type of primary bone cancer, but still is a rare cancer. The development of bone metastases is a common event for the cancer patient and the main cause of treatment failure and death, being chronic pain syndrome the most important complication. There are currently several therapeutic modalities for the treatment of metastatic bone disease, including radiation therapy. Treatment with radionuclides (β- and α-particle emitters and Auger electron cascades) is a safe and effective tool of medicine. There is a great deal of interest in diphosphonic acids in nuclear medicine as ligands for radiometals in bone-seeking diagnostic and therapeutic agents. Several radiopharmaceuticals have been designed with the phosphonates as ligands. A recent approach to develop an effective radiopharmaceutical for therapy of bone cancer was the design of a water-soluble polymer that would exploit the disrupted vasculature in tumors according to the enhanced permeability and retention effect. To enhance the effect of radionuclide therapy on the cancer cells, new strategies have recently been investigated, such as the combined radionuclide and chemotherapy, high-dose radionuclide therapy, and repeated radionuclide therapy.

Radionuclide therapy beyond radioiodine

For decades, Iodine-131 has been used for the treatment of patients with thyroid cancer. In recent years, increasingly, other radiopharmaceuticals are in clinical use in the treatment of various malignant diseases. Although in principle these therapies-as in all applications of radionuclides-special radiation protection measures are required, a separate nuclear medicine therapy department is not necessary in many cases due to the lower or lack of gamma radiation. In the following article, four different radionuclide therapies are more closely presented which are emerging in the last years. One of them is the "Peptide Receptor Radionuclide Therapy," the so-called PRRT in which radiolabeled somatostatin (SST)-receptor(R) ligands are used in patients with neuroendocrine tumors. On the basis of radiolabeled antibodies against CD20-positive cells, the so-called radioimmunotherapy is used in the treatment of certain forms of malignant lymphoma. In primary or secondary liver tumors, the (90)Y-labeled particles can be administered. Last but not the least, the palliative approach of bone-seeking radiopharmaceuticals is noted in patients with painful bone metastases.

New knowledge about the bremsstrahlung image of strontium-89 with the scintillation camera

OBJECTIVE

Strontium-89 ((89)Sr) chloride has been used to treat metastases in bone. A method to visualize the distribution of (89)Sr chloride with a scintillation camera was developed in 1996. Studies using bremsstrahlung imaging have shown that (89)Sr accumulates in bone and that the bremsstrahlung generated from biological tissue surrounding bone does not exceed 30 keV. However, it was not clear how low-energy bremsstrahlung from bone can produce peak energy levels of around 75 keV. We speculate that a different (unidentified) factor is involved.

METHODS

The energy spectrum of an (89)Sr source was acquired with a scintillation camera with or without a low-to-medium-energy general-purpose collimator. The energy window was set at 20-650 keV for 4 windows. A 50-mm thick acrylic block was placed between the scintillation camera and the (89)Sr source to exclude the effects of bremsstrahlung. The energy spectrum of (89)Sr covered with lead was acquired using the scintillation camera without a collimator.

RESULTS

With the collimator the energy spectrum curve was similar to that without the 50 mm of acrylic. The energy spectrum curve showed peaks at about 75, 170, and 520 keV. Without the collimator the energy spectrum showed a similar curve but no peak at 75 keV peak. The curve was similar to that obtained with the scintillation camera and the collimator; however, the curve obtained when the (89)Sr source had been placed in a lead container was similar to that obtained when the source was unshielded, and the collimator was not attached to the scintillation camera.

CONCLUSION

If bremsstrahlung of (89)Sr produces an image, a low-energy spectrum region should decrease when acrylic is placed between the (89)Sr source and the scintillation camera. However, similar curves were obtained both with the acrylic in place and without the acrylic. Therefore, we believe that the radiation detected by the scintillation camera was not bremsstrahlung due to the beta rays of (89)Sr. Most (89)Sr preparations are contaminated by (85)Sr, and most of the gamma ray energy of (85)Sr is 514 keV. The scintillation camera detected the characteristic X-ray energy of about 75 keV from the materials of the collimator (lead and others) through interaction with the gamma rays of (85)Sr.

Radionuclide Therapy of Bone Metastases

The skeleton is a potential metastatic target of many malignant tumors. Up to 85% of prostate and breast cancer patients may develop bone metastases causing severe pain syndromes in many of them. In patients suffering from multilocular, mainly osteoblastic lesions and pain syndrome, radionuclide therapy is recommended for pain palliation. Low-energy beta-emitting radionuclides ((153)samarium-ethylenediaminetetrameth-ylenephosphonate (EDTMP) and (89)strontium) deliver high radiation doses to bone metastases and micrometastases in the bone marrow, but only negligible doses to the hematopoietic marrow. The response rate regarding pain syndrome is about 75%; about 25% of the patients may even become pain free. The therapy is repeatable, depending on cell counts. Concomitant treatment with modern bisphosphonates does not interfere with the treatment effects. Clinical trials using a new, not yet approved nuclide ((223)Radium) and/or combinations of chemotherapy and radionuclides are aiming at a more curative approach.

Effectiveness of radioisotope therapy in bone metastases, based on personal experience

Aim of the study

Metastatic bone disease is a major clinical and therapeutic problem. It is particularly marked in patients with advanced breast and prostate cancer. Taking into account the diversity of the consequences of skeletal metastases, multidisciplinary patient care should be provided. Among the available treatment methods, radionuclide therapy plays a significant role. The goal of the study was to evaluate and compare the effectiveness of treatment with radionuclides of strontium-89 and samarium-153 in patients with generalized bone metastases.

Material and methods

We analyzed 132 patients with poor pharmacological control of bone pain, caused by multiple metastases due to breast or prostate cancer. In this group of patients radionuclide therapy was administered in the Krakow branch of Oncology Centre between 2002 and 2010.

Results

In the group treated with strontium-89 and samarium-153 total analgesic response rate obtained, was 69% and 83.3%, respectively. In both groups, a significant reduction in analgesics consumption was observed, higher in the group treated with samarium-153. In 14 patients with satisfactory analgesic effect after the first administration of a radioisotope, second administration of radionuclide therapy was attempted at the time of symptoms reappearance. The positive response was achieved in 12 patients. Treatment with both radionuclides was well tolerated.

Conclusions

Radionuclide therapy with strontium-89 and samarium-153 is effective and well tolerated treatment of pain caused by the skeletal metastases. In some cases it is possible to obtain equally good analgesic effect with repeated radioisotopes administration.

Concurrent use of Sr-89 chloride with zoledronic acid is safe and effective for breast cancer patients with painful bone metastases

Our aim in this study was to examine the safety and efficacy of the concurrent use of the radiopharmaceutical strontium-89 (Sr-89) chloride with zoledronic acid in standard anticancer therapy for breast cancer patients with painful multifocal bone metastases. The study comprised 16 breast cancer patients with painful multifocal bone metastases detected by bone scintigraphy, computed tomography or magnetic resonance imaging. All patients were treated with Sr-89 and zoledronic acid concurrently between March 2007 and February 2011 as part of a standard therapeutic regimen comprising chemotherapy, endocrine therapy, molecular targeting therapy and targeted radiotherapy. Sr-89 was administered intravenously at 2 MBq/kg to a maximum of 141 MBq per person. Safety was evaluated according to myelotoxicity as measured by the Common Terminology Criteria for Adverse Events (v3.0). To assess treatment efficacy, we monitored changes in analgesic drug dosages. Furthermore, bremsstrahlung imaging after the administration of Sr-89 was utilized to examine the relationship between the accumulation of Sr-89 in metastatic sites and treatment efficacy. Based on the results, a total of 14 out of 16 patients (88%) reported bone pain relief, indicating a high efficacy of Sr-89 combined with zoledronic acid. In responsive cases, a strong uptake of Sr-89 was observed on bremsstrahlung imaging at the same sites indicated by (99m)Tc bone scintigraphy. Moreover, severe myelosuppression (> grade 3) was not observed, and adverse events were tolerable. In conclusion, the use of Sr-89 with zoledronic acid in breast cancer patients with painful bone metastases was safe and effective when administered concurrently with other standard therapies. In the future, the treatment with Sr-89 at the early stage should be considered, and a large-scale clinical study should be conducted.

Systemic metabolic radiopharmaceutical therapy in the treatment of metastatic bone pain

Bone pain due to skeletal metastases constitutes the most common type of chronic pain among patients with cancer. It significantly decreases the patient's quality of life and is associated with comorbidities, such as hypercalcemia, pathologic fractures and spinal cord compression. Approximately 65% of patients with prostate or breast cancer and 35% of those with advanced lung, thyroid, and kidney cancers will have symptomatic skeletal metastases. The management of bone pain is extremely difficult and involves a multidisciplinary approach, which usually includes analgesics, hormone therapies, bisphosphonates, external beam radiation, and systemic radiopharmaceuticals. In patients with extensive osseous metastases, systemic radiopharmaceuticals should be the preferred adjunctive therapy for pain palliation. In this article, we review the current approved radiopharmaceutical armamentarium for bone pain palliation, focusing on indications, patient selection, efficacy, and different biochemical characteristics and toxicity of strontium-89 chloride, samarium-153 lexidronam, and rhenium-186 etidronate. A brief discussion on the available data on rhenium-188 is presented focusing on its major advantages and disadvantages. We also perform a concise appraisal of the other available treatment options, including pharmacologic and hormonal treatment modalities, external beam radiation, and bisphosphonates. Finally, the available data on combination therapy of radiopharmaceuticals with bisphosphonates or chemotherapy are discussed.

Combined therapy of Sr-89 and zoledronic acid in patients with painful bone metastases

PURPOSE

We evaluated the pain response and daily discomfort in patients with painful bone metastases treated by merging 89Sr-chloride and zoledronic acid. The results were compared with those of patients who received 89Sr-chloride or zoledronic acid separately.

METHODS

25 patients (12 women; mean age 65+/-13 years) chronically treated with zoledronic acid underwent bone pain palliation with 150 MBq of 89Sr-chloride at least 6 months later that bisphoshonate therapy started (group A). 13 patients (6 women; mean age 70+/-12 years) received 89Sr-chloride alone (group B) and 11 patients (5 women; mean age 69+/-12 years) were chronically treated and continued to receive only zoledronic acid therapy (group C), both constituted the control groups. Patients kept a daily pain diary assessing both their discomfort and the pain of specific sites by using a visual analog scale (VAS), rating from 0 (no d iscomfort-no pain) to 10 (worst discomfort-pain). These diaries were reviewed weekly for 2 months and three different physicians rated the pain response on a scale of -2 (considerable deterioration) to +2 (considerable improvement).

RESULTS

Baseline characteristics were similar in the three groups. The reduction of total discomfort and of bone pain in the group A was significantly greater as compared to group B (P<0.01) and group C (P<0.01). During the monitored period, a significant improvement of clinical conditions was observed in the group A, varying the rate from -1 to 1 as compared to both groups B and C in which the rate changed from -1 to 0.

CONCLUSION

Our findings indicate that combined therapy of 89Sr-chloride and zoledronic acid in patients with painful bone metastases is more effective in treating pain and improving clinical conditions than 89Sr-chloride or zoledronic acid used separately.

Radioisotopes for the palliation of metastatic bone cancer: a systematic review

Strontium-89 and samarium-153 are radioisotopes that are approved in the USA and Europe for the palliation of pain from metastatic bone cancer, whereas rhenium-186 and rhenium-188 are investigational. Radioisotopes are effective in providing pain relief with response rates of between 40% and 95%. Pain relief starts 1-4 weeks after the initiation of treatment, continues for up to 18 months, and is associated with a reduction in analgesic use in many patients. Thrombocytopenia and neutropenia are the most common toxic effects, but they are generally mild and reversible. Repeat doses are effective in providing pain relief in many patients. The effectiveness of radioisotopes can be greater when they are combined with chemotherapeutic agents such as cisplatin. Some studies with 89Sr and 153Sm indicate a reduction of hot spots on bone scans in up to 70% of patients, and suggest a possible tumoricidal action. Further studies are needed to address the questions of which isotope to use, what dose and schedule to use, and which patients will respond.

Management of bone metastases in cancer: a review

The presence of bone metastases is indicative of disseminated disease and typically indicates a short-term prognosis in cancer patients. Palliation of symptoms is the primary goal of therapy, with multidisciplinary efforts yielding the best results. New classes of drugs, such as bisphosphonates that significantly increase the time to first skeletal-related event (SRE), represent useful tools for the treatment of bone metastases. While the optimal duration of therapy needs to be defined, there is clinical benefit derived from the use of this class of agents. A potential role for bisphosphonates in the prevention of bone metastases is under current evaluation in clinical trials encompassing different solid tumor types. In combination with ongoing clinical trials, basic research to identify potential novel targets in the tumor cells-bone microenvironment will further define future strategies in the treatment of bone metastases.

Radiopharmaceuticals for the palliation of painful bone metastases—a systematic review

BACKGROUND AND PURPOSE

The purpose was to develop a systematic review that would address the following question: what is the role of radiopharmaceuticals in the palliation of metastatic bone pain in adults with uncomplicated, multifocal painful bone metastases whose pain is not controlled with conventional analgesic regimens? The outcomes of interest are pain response, analgesic consumption, overall survival, adverse effects and quality of life.

MATERIALS AND METHODS

A systematic review of the English published literature was undertaken to provide evidence relevant to the above outcomes.

RESULTS

Six randomized phase III trials, two randomized phase II trials and one randomized crossover trial of strontium-89 were reviewed. A randomized phase III trial comparing strontium-89 plus cisplatin with strontium-89 plus placebo reported a significantly higher proportion of patients experiencing pain relief for a significantly longer duration with strontium-89 plus cisplatin. A randomized phase III trial comparing adjuvant strontium-89 with placebo following radiotherapy reported a higher proportion of pain-free patients with strontium-89. Patients who received strontium-89 also experienced fewer new sites of bone pain. A second, but underpowered study failed to confirm these results. In one randomized trial of strontium-89 versus radiotherapy (hemibody or local), patients treated with strontium-89 developed fewer new sites of pain. In a second trial comparing strontium-89 versus local radiotherapy, median overall survival was improved with radiotherapy, while pain response and time-to-progression were similar in the two groups. One randomized phase III trial reported no difference in pain relief between strontium-89 and placebo. Three randomized phase III trials and two randomized phase II trials investigating samarium-153 were reviewed. In a randomized phase III trial of three different doses of samarium-153, the pain responses were similar for all three doses. In a randomized phase III trial of two different doses of samarium-153 versus placebo, the complete pain response rate was significantly higher with the higher dose of samarium-153 compared with placebo. In a randomized phase III trial comparing samarium-153 with placebo, significant differences favouring samarium-153 were reported for pain and opiate use. In addition, one randomized phase III trial, two randomized phase II trials, one randomized crossover trial and 13 phase II or phase I trials of rhenium, one phase I trial of tin-117 m and one phase II trial of phosphorus-32 were reviewed. The majority of patients treated in trials of radiopharmaceuticals where histology was specified had metastatic breast cancer (approximately 5-10% of patients reported), metastatic hormone-refractory prostate cancer (80-90% of patients reported) or metastatic lung cancer (5-10% of patients reported). Information on histologic subtype was not available for a significant proportion of patients treated on trials (30-40% of patients reported).

CONCLUSIONS

Use of single-agent radiopharmaceuticals (strontium-89 and samarium-153) should be considered as a possible option for the palliation of multiple sites of bone pain from metastatic cancer where pain control with conventional analgesic regimens is unsatisfactory and where activity on a bone scan of the painful lesions is demonstrated. Ongoing clinical research should seek to establish the benefit of newer radiopharmaceuticals and radiopharmaceuticals in combination with other systemic therapies.

Role of strontium-89 as adjuvant to palliative external beam radiotherapy is questionable: results of a double-blind randomized study

PURPOSE

To explore the efficacy of adjuvant (89)Sr applied with external beam radiotherapy (EBRT) to treat bone metastases.

METHODS AND MATERIALS

Ninety-five patients were randomized to (89)Sr (Arm A) or saline (Arm B) on Day 1 of EBRT to demonstrate a reduction in 3-month physician-assessed subjective progression from 70% to 45%.

RESULTS

At 3 and 6 months, no difference between treatment arms was observed in the progression rate. At 3 months, the physician-assessed response rate for all patients was 25%, with 46% of the patients progressing. The pretreatment use of opiates was independently associated with short progression-free survival. On the basis of the quality-of-life assessments, pain relief occurred in 50% of patients and 32% experienced improvement in global quality of life, without impact from (89)Sr. Differences were observed between the physician evaluation of radiotherapy efficacy and the patient assessment. In Arm A, serum alkaline phosphatase, but not serum prostate-specific antigen, decreased during the first 3 months after treatment.

CONCLUSION

(89)Sr, adjuvant to ERBT, does not seem to reduce the number of patients with subjective progression at 3 months. Patients should be referred for palliative RT before their bone pain requires high doses of opiates. In radiotherapy trials, the evaluation of pain and pain relief remains problematic because of the confounding use of analgesics.

Strategies for improving quality of life in older patients with metastatic breast cancer

Given both the increase in the mean age of the population of Western countries and the high incidence of breast cancer beyond the age of 65 years, it is evident that breast cancer in older women will be a very common problem for the medical oncologist. Metastatic breast cancer is still not amenable to a cure; therefore quality of life during therapy is an important issue, which until recently has been poorly investigated. Similarly, despite recent advances in breast cancer therapy, physicians have been reluctant to enrol older patients in clinical trials, and there is a lack of data regarding this population. This review focuses on quality-of-life issues during metastatic breast cancer treatment in geriatric patients, comparing the standard therapeutic options and newer approaches. Although first-line endocrine therapy with tamoxifen remains a standard treatment, the newer third-generation aromatase inhibitors provide similar or better efficacy with fewer adverse effects and a better quality of life. It has been a common belief that chemotherapy impairs quality of life, but recent studies in advanced breast cancer have shown that this therapy has a positive effect on quality of life, at least in responders. Consequently, chemotherapy should not be denied to elderly patients with metastatic breast cancer, provided a prior geriatric assessment is performed to evaluate the risk-benefit ratio. New chemotherapy strategies, such as the taxanes and orally administered chemotherapy, represent a very attractive alternative for a better quality of life in elderly patients with metastatic breast cancer.

Strategies for management of prostate cancer-related bone pain

Prostate cancer is one of the most common malignancies and a leading cause of cancer-related death in men worldwide. In the majority of cases, prostate cancer metastases to the skeleton, in which case cancer-related bone pain becomes a major cause of morbidity. Androgen ablation is the treatment of choice for securing regression of skeletal metastases in the majority of cases. Intermittent androgen ablation is an attractive alternative, aimed at minimising adverse effects of hormone deprivation but also potentially delaying hormone-refractoriness. The development of hormone-refractoriness is heralded by a significant increase in morbidity largely because of escalating bone pain caused by the progression of the metastatic process. Skillful use of analgesics is initially successful but eventually fails to control symptoms. Localised metastases are best treated with local radiotherapy that is rapidly effective. Over the last few years, it has become clear that therapeutic modalities using bone-seeking radionuclides or bisphosphonates have been effective in the palliation of prostate cancer-related bone pain, although not affecting survival. The main limiting factor with the use of radionuclides is bone marrow suppression, also a feature of the very late stages of prostate cancer. Bisphosphonates do not carry this disadvantage. Results of large double-blind, placebo-controlled studies should be awaited, however, before advocating the widespread use of these agents in the management of patients with prostate cancer and skeletal metastases.

Metastatic bone pain palliation with 89-Sr and 186-Re-HEDP in breast cancer patients

AIM

The study evaluates the therapeutic efficacy of Strontium-89-chloride (89Sr) and 186Re-1,1-hydroxyethylidene diphosphonate (186Re-HEDP) in the palliation of painful bone metastases from breast cancer.

PATIENTS AND METHODS

Fifty patients with painful multifocal bone metastases from breast cancer entered the study and were randomized into two groups according to the radiopharmaceutical used: 148 MBq 89Sr i.v. (Group A: 25 patients) and 1406 MBq 186Re-HEDP i.v. (Group B: 25 patients). Pain palliation was evaluated on the basis of the Wisconsin pain test improvement at two months and response was graded as complete, partial, minimal or absent. Hematological toxicity and side effects were reported according to WHO guidelines.

RESULTS

The global response rate was 84% (21/25) for 89Sr and 92% (23/25) for 186Re-HEDP, respectively. The onset of pain palliation appeared significantly earlier in Group B (p < 0.0001). The duration of pain relief ranged from two months to 14 months (mean of 125 days with a median value of 120 days) in Group A and from one month to 12 months (mean of 107 days with a median value of 60 days) in Group B (p = 0.39). A moderate hematological toxicity was apparent in both groups. Platelet and white blood cell counts returned to baseline levels within 12 weeks after 89Sr administration and 6 weeks after 186Re-HEDP administration (p < 0.01).

CONCLUSIONS

Both 89Sr and 186Re-HEDP are effective and safe in bone pain palliation in breast cancer with the latter showing a significantly faster onset of pain relief.

Perioperative considerations in patients with metastatic bone disease

Preoperative assessment of patients with metastatic bone disease includes a history and physical examination, laboratory evaluation, and standard radiographs. Perioperative diagnostics include technetium bone scan, CT scans, MR imaging, positron emission tomography, and biopsy. The role of preoperative tumor embolization and vena cava filter placement is discussed in this article. Guidelines for pain control are provided. Surgical planning and instrument considerations for long bone lesions, periarticular lesions, and pelvis and acetabular lesions are addressed. The importance of rehabilitation for patients with metastatic bone disease is emphasized.

Usefulness of strontium-89 for bone pain palliation in metastatic breast cancer patients

Most studies of prostate cancer have shown that strontium-89 chloride (89Sr) is effective in the palliation of metastatic bone pain, refractory to conventional analgesia. The aim of this study was to evaluate the usefulness of 89Sr for bone pain palliation in breast cancer patients. Forty women were treated with 148 MBq of 89Sr. Six patients were retreated, receiving two or more doses. The Karnofsky performance status was assessed and pain and analgesia were scored on scales of 9 and 5 points, respectively. The efficacy of 89Sr was evaluated at 3 months of treatment. The response was good in 60% of the patients and partial in 32%; there was no response in the remaining 8% (pre-treatment Karnofsky < or = 60). The duration of the response was 120+/-143 days. In the patients retreated, the response was good in 83% and partial in 17%, without significant differences compared with the first dose, but the pre-treatment Karnofsky and the duration of the efficacy were lower (P < 0.05). A transient and slight decrease of leukocyte and platelet counts after the first month of treatment with 59Sr was observed. In conclusion, breast cancer patients with metastatic bone pain can benefit from therapy with 89Sr. If necessary, the treatment may be repeated safely and with the same efficacy as is achieved after the first dose. A low functional performance status could be a cause of the lower effectiveness of 89Sr.

Use of radionuclides for the palliation of bone metastases

Pain palliation with bone-seeking radiopharmaceuticals is an effective and cost-effective management tool in patients with advanced cancer metastatic to bone. Strontium-89 ((89)Sr) (Metastron) and samarium-153 ((153)Sm) EDTMP (Lexidronam) are licensed for use in patients in the United States. Patients with a positive bone scan using technetium 99m methylene diphosphonate ((99m)Tc MDP) are eligible for treatment, and indications and contraindications for use are now well defined. The evidence in the literature now suggests that the radiopharmaceuticals can significantly reduce pain and analgesic requirements, can improve quality of life, can reduce lifetime radiotherapy requirements and management costs, and may slow the progression of painful metastatic lesions. Retreatment is safe and effective. Rhenium-186 ((186)Re) HEDP and Tin-117m diethylenetriaminepenta-acetic acid (DTPA) are in phase II/III trials to evaluate efficacy and compare efficacy with the licensed agents. Phosphorus-32 ((32)P) has been reassessed in two trials evaluating efficacy in comparison with (89)Sr and safety. Toxicity is reversible myelosuppression, which may be significant, and the treatments should not be given to patients with suspected disseminated intravascular coagulation.

Palliative therapy with bone seeking radiopharmaceuticals

Pain palliation with unsealed source therapy is an effective and cost effective treatment for patients with cancer metastatic to bone who present with progressive pain. Used in the appropriate setting this form of therapy can make an enormous contribution to a very large number of patients.