Radionuclide therapy, also known as targeted radionuclide therapy or molecular radiotherapy, is a promising approach in the treatment of solid tumors. It involves the use of radioactive isotopes, called radionuclides, which are specifically targeted to cancer cells, delivering localized radiation to destroy or control the growth of tumors. This therapeutic modality offers several advantages over conventional treatments, such as surgery, chemotherapy, and external beam radiation therapy, particularly in the management of certain types of solid tumors. One of the key advantages of radionuclide therapy is its ability to deliver radiation directly to tumor cells, sparing surrounding healthy tissues. This targeted approach minimizes the systemic toxicity associated with conventional therapies, which often affect both cancerous and normal cells. By binding to specific receptors or antigens expressed on cancer cells, radionuclides can deliver a high dose of radiation precisely to the tumor site, maximizing the therapeutic effect while minimizing collateral damage. Radionuclide therapy is particularly effective in the treatment of neuroendocrine tumors (NETs). NETs are a heterogeneous group of tumors that arise from cells of the neuroendocrine system, and they often express somatostatin receptors. Radionuclides, such as lutetium-177 or yttrium-90, labeled with somatostatin analogs, are used to target these receptors. When the radionuclide binds to the somatostatin receptor on the tumor cell, it emits radiation that damages the DNA, leading to cell death. This approach has shown significant clinical efficacy in controlling tumor growth and improving patients' quality of life. Another application of radionuclide therapy in solid tumors is the treatment of bone metastases. Bone metastases occur when cancer cells spread from their primary site to the bone, resulting in significant morbidity and pain for patients. Radionuclides, such as radium-223, selectively target areas of increased bone turnover, where cancer cells preferentially accumulate. By emitting alpha particles, radium-223 damages tumor cells and the surrounding microenvironment, resulting in pain relief and improved survival outcomes. In addition to neuroendocrine tumors and bone metastases, radionuclide therapy is being investigated in other solid tumors, including prostate cancer, breast cancer, and liver cancer. For example, prostate-specific membrane antigen (PSMA) is highly expressed in prostate cancer cells, and radionuclides labeled with PSMA-targeting ligands, such as lutetium-177 or actinium-225, have shown promising results in the treatment of advanced prostate cancer. Similarly, radionuclide therapies targeting specific antigens or receptors expressed on breast cancer or liver cancer cells are being explored as potential treatment options. Despite the promising results, there are still challenges in the widespread adoption of radionuclide therapy. One of the limitations is the availability of suitable radionuclides with appropriate half-lives and decay characteristics for different tumor types. The production and delivery of these radionuclides can be logistically complex and expensive. Furthermore, the precise dosimetry and patient selection criteria for radionuclide therapy require further refinement to optimize treatment outcomes. In conclusion, radionuclide therapy represents a promising approach in the treatment of solid tumors. Its targeted nature allows for the delivery of localized radiation to tumor cells, minimizing systemic toxicity. The efficacy of radionuclide therapy has been demonstrated in neuroendocrine tumors and bone metastases, and ongoing research is exploring its potential in other types of solid tumors. With further advancements in radionuclide production, delivery systems, and patient selection criteria, this therapeutic modality has the potential to become an integral part of cancer treatment, offering improved outcomes and quality of life for patients with solid tumors.