Targeted tumor radiotherapy

Abstract

Targeted tumor radiotherapy is selectively delivery of curative doses of radiation to malignant sites. The aim of the targeted tumor radiotherapy is to use the radionuclides which have high LET particle emissions conjugated to appropriate carrier molecules. The radionuclides are selectively collected by tumor cells, depositing lethal doses to tumor cells while no admission occur to normal cells. In theory, targeted radiotherapy has several advantages over conventional radiotherapy since it allows a high radiation dose to be administered without causing normal tissue toxicity, although there are some limitations in the availability of appropriate targeting agents and in the calculations of administered doses. Therefore, for routine clinical applications more progress is still needed. In this article, the potential use of targeted tumor radiotherapy is briefly reviewed. More general aspects and considerations, such as potential radionuclides, mechanisms of tumor targeting was also outlined.

Palliative treatment of metastatic bone pain with radiopharmaceuticals: A perspective beyond Strontium-89 and Samarium-153

“…In this regard, a shorter half-life is an advantage to achieve large doses per unit time (Unak, 2002). Different half-lives imply different dose rates, if the surviving cells in the irradiated volume are continuously proliferating (Guerra Liberal et al, 2014;Neves et al, 2005).…”

“…Radionuclide therapy is characterized by the reasonably selective delivery of therapeutic doses of radiation to systemically dispersed target tissues, with generally limited toxicity and few long-term side-effects (Unak, 2002). The basis of successful radionuclide therapy relies on a high concentration and adequate retention of the radiopharmaceutical at the tumour site.…”

“…However, high-energy β -particles, with a range of several millimeters in tissues, can irradiate cells nearby the targeted tumor. Conversely, α particles (typical penetration range of less than 100 µm) (Harrison et al, 2013) and Auger electrons (penetration range of several nanometers to micrometers) have shorter penetration ranges and higher linear energy transfer (LET) (Unak, 2002).…”

“…For short-range particles, such as Auger electrons, this means the carrier molecule should be able to cross the cellular membrane either by passive diffusion or via specific carrier mediated process, in order to reach the cell nucleus and to associate with the deoxyribonucleic acid (DNA) complex for a time corresponding to the radionuclide half-life (Unak, 2002). Cell and tissue studies have shown that once Auger electron emitters are introduced into the cell's cytoplasm, they will present similar effects to those induced by low LET radiations, but when they are introduced close to DNA, the survival curves will be similar to those obtained with high LET α particles (Sastry, 1992).…”

Radiotherapy, cancer and some anatomical structures related with the pelvic floor: an evaluation of the scientific literature

“…It can also be used to treat leukemia and lymphoma (cancers of the blood-forming cells and lymphatic system, respectively) (Denardo and Denardo, 2006). However, radiotherapy is a complex procedure and requires the patients to make a number of hospital visits to complete a full course of treatment (Unak, 2002;Perkins, 2007). X-rays were the first form of ionizing radiation to be used for the treatment of cancer.…”