Use of radionuclides for the palliation of bone metastases

Evaluation of a freeze-dried kit for EDTMP-based bone-seeking radiopharmaceuticals

A freeze-dried kit developed for formulation of ethylenediamine-tetramethylenephosphonic acid (EDTMP) chelates with "pain-palliation" radiolanthanides (e.g., 153Sm and 177Lu) or "diagnostic" 99mTc has been evaluated, meeting quality and safety criteria required for medicinal use. The EDTMP kit enables an instant one-step preparation of a radiopharmaceutical of high radiochemical purity (>99%) and has a sufficiently long shelf life. Comparative biodistribution studies of 177Lu-EDTMP and 99mTc-EDTMP prepared from the kit revealed similar tissue uptake and clearance to those obtained for pre-formulated 153Sm-EDTMP. The most significant difference was observed for 99mTc-EDTMP, which shows a high retention in kidney, reaching ca. 2% ID after 90min p.i.v.Although preliminary clinical evaluations suggest that 99mTc-EDTMP possesses limited value for bone scintigraphy, application of the radiopharmaceutical for specific diagnostic purposes may still be considered, e.g., investigation of bone metastases or ossification processes in inflammatory spondyloarthropathy.

Novel techniques in the delivery of radiation in pediatric oncology

The field of radiation oncology continues to develop at a rapid pace, due to concurrent progress in high speed computing, improved sensitivity in diagnostic imaging (both anatomic and physiologic), and the introduction of rational new therapeutics built on solid radiobiologic principles. These innovations will become critically important in the field of pediatric oncology, as they will allow for an increased therapeutic ratio in the developing child. Maximizing the benefit of lower dose radiation through the use of radiation modifiers (hypoxic cell sensitizers, signal transduction pathway inhibitors, concurrent chemotherapy), increasing the tolerance of normal tissues (radioprotectors) and tailoring the target area more closely to the desired critical tissues (IMRT, functional simulation with PET and MRS, radiolabeled monoclonal antibodies) will lessen the short and long term toxicity of radiation and increase its effectiveness.

Synthesis, characterization and biodistribution of bisphosphonates Sm-153 complexes: correlation with molecular modeling interaction studies

Bisphosphonates (BPs) are characterized by a P-C-P backbone structure and two phosphonic acid groups bonded to the same carbon, and are established as osteoclast-mediated bone resorption inhibitors. The nature of the groups attached to the central carbon atom are responsible in determining the potency of bisphosphonates as anti-resorption drugs. However, it is not yet clear the exact relationship between their molecular structure and pharmacologic activities. In this study, molecular geometries of pamidronate, alendronate and neridronate, differing only in the length of the aliphatic chains, were predicted by molecular mechanics and their interactions with hydroxyapatite, the main bone mineral component, were examined. We report the synthesis and radiochemical characterization of 153Sm complexes with pamidronate, alendronate and neridronate. Hydroxyapatite binding and biodistribution studies of these complexes have shown a good correlation with the theoretical molecular modeling interaction studies. So, it is possible to conclude that computational chemistry techniques are a good approach to evaluate specific interactions and may play a relevant role in determining the relative ability of BPs to mineral bone, and open new perspectives to the design of new BPs with increased pharmacological activity. These techniques could be extended to BPs as ligands to carrier radioactive metals, aiming for new bone therapeutic radiopharmaceuticals.

Clinical trial design and scoring of radionuclide therapy endpoints: normal organ toxicity and tumor response

Like other cancer therapy agents under development, radionuclide therapies are usually evaluated in a progressive series of clinical trials after basic science, human cell culture and animal model studies. Toxicities during these trials are graded using common scoring systems that are in widespread use such as the Common Toxicity Criteria from the National Cancer Institute. Information on normal tissue toxicity from radionuclides is more limited than that from external beam radiation and is more variable. Variability is likely due to many biologic factors as well as less precise dose quantitation than those used in external beam radiation practice. As expected based on known radiobiologic effects, tolerance to radionuclide therapy appears to exceed that from high dose rate external beam radiation in most organs. Although the correlation between reported dose estimates and toxicity has progressively and substantially improved over the past two decades, further progress is needed to establish optimal toxicity predictive relationships. Continued refinement of dosimetry techniques and standardization is expected to increase the accuracy and comparability of radiation dose reports between institutions as well as improve dose/response correlation.

Update on pain management for advanced genitourinary cancer

PURPOSE

Pain is a significant problem in many patients with genitourinary malignancy at all stages of disease. Optimal pain control becomes a primary concern as disease progresses and other therapies are exhausted. The selection of the most appropriate therapy becomes difficult without an understanding of the underlying mechanisms of pain and the available therapies.

MATERIALS AND METHODS

A review of the literature regarding the mechanisms and assessment of pain syndromes was performed. All available therapies were investigated with respect to conservative management with opioid medications and adjuvant drugs, and the indications for invasive techniques.

RESULTS

Increased understanding of the mechanisms and classification of pain syndromes has led to improved assessment and treatment. Despite these advances a significant number of patients have inadequate pain control and the education of treating physicians remains an important target for improving this situation.

CONCLUSIONS

Opioid medication is the mainstay of therapy in the majority of patients but with the appropriate addition of other adjuvant drugs patients may achieve optimal pain control without unwanted side effects. A few patients benefit from more invasive techniques, including plexus blocks and neuraxial infusion therapy, and the indications for these treatments are discussed. These therapies have largely superseded neuroablative procedures that are more destructive and associated with higher morbidity.

Palliative radiation therapy for gynaecological malignancies

Patients with advanced, recurrent, or metastatic gynaecological malignancies constitute a heterogenous population with diverse symptomatology. Progressive abdominopelvic disease can result in vaginal or diffuse pelvic bleeding, pain, and visceral or lymphovascular obstruction. Gynaecological cancer can also develop debilitating metastases, in particular to bone, central nervous system, or chest. Radiation therapy is a local-regional treatment modality, that, when applied judiciously, can lead to substantial symptomatic relief and tumour response. Individualized application is necessary, balancing efficacy and patient convenience versus treatment intensity, expected duration of palliation and potential toxicity. Important factors to consider are a patient's performance status, extent and sites of tumour, specific symptoms, and life expectancy. The optimal incorporation of radiotherapy is best achieved in the context of a multidisciplinary approach that addresses all facets of palliative care in patients with incurable gynaecological malignancies, to maximize their quality of life and functional level.