Recent developments in Nuclear Medicine provide additional treatment alternatives, particularly for patients unable to undergo surgery. These treatments prolong cancer patients' lives and improve their quality of life by locating cancerous tissue through targeted precision treatment methods.
Treatment Based on Cancer Cell Characteristics
Modern cancer treatment approaches are mostly consideredunder the heading of targeted treatments. The targets here are cancer cells. Abnormally multiplying cancer cells differ from normal cells because of various proteins on their surfaces or molecules inside them. In recent years, precision treatments have been developed using molecules able to identify cancer cell characteristics or vulnerabilities. When administered orally or intravenously, these molecules travel to the cancerous area.
If a special molecule targets a cancer cell, drugs, atoms or other destructive substances can be loaded onto it according to the treatment. These special carriers attached to molecules selectively deliver therapeutic substances to the target cancer cells, destroying diseased tissue at the cellular level. Healthy tissues are therefore affected less and more effective doses can be used.
New Options for Patients Unable to Undergo Surgery
Molecular treatment provides a new weapon against cancer. It offers an additional chance when surgery cannot be used or patients have exhausted all treatment options. These new methods can be applied as a final blow to malignant cells in people with more advanced disease. However, as experience grows, such treatments may also be used at earlier stages of disease.
The Carrier Molecule Principle in Imaging Too
Imaging cancer cells that have spread throughout the body is also performedusing the same principle. Substances acting as molecular taxis that deliver to the appropriate address according to cancer cell characteristics allow the distribution of cells in the body to be visualized. Compared with earlier imaging methods, molecular imaging evaluations produce much more successful results. Substances providing both treatment and imaging through the same method can also be used. Theranostics (a combination of the Latin words therapy, meaning treatment, and diagnostics, meaning diagnosis) is the name for these substances, which enable more effective monitoring of drug distribution and disease course simultaneously with treatment.
Effective Use in Prostate Cancer
Prostate cancerdiagnosis and treatment have begun using new molecular diagnostic and therapeutic methods, which will become more widespread in the near future. Blood tests include a tumor marker commonly called PSA . After prostate cancer is diagnosed, imaging can determine its stage. Molecular targeted treatments follow the same principle. Using the prostate cancer-specific PSMA protein, PET/CT imaging has been developed. PSMA PET/CT in prostate cancer with the potential to spread has the potential to identify metastasis and prevent unnecessary interventions and treatments. In patients found to have metastatic disease resistant to standard treatments, targeted lutetium PSMA treatment can be administered using the high-energy atom lutetium 177. Another molecular treatment newly introduced for prostate cancer is radium 223. Radium 223 can target bone metastases of hormone-resistant prostate cancers. Radium 223 treatment has been shown to prolong survival in prostate cancers with widespread bone metastases.
Atom-Loaded Beads Against Cancer
In liver cancers, reaching the diseased area through blood vessels and delivering radioactively labeled microspheres (beads) can destroy cancerous tissue. Radioembolization or radio-microsphere treatment is the name of the procedure, performed through cooperation between Nuclear Medicine, Radiology and Medical Oncology departments. It can be used in primary liver cancers or disease spread to the liver from other organs (metastatic disease). Treatment uses microscopic, radioactive, high-energy yttrium-90 containing beads. Radioactive beads delivered through blood vessels to the area feeding the tumor using angiography can destroy tumor cells and possible nearby microscopic spread by irradiating them at the cellular level . Treatment can prevent disease progression, lead to regression and contribute to survival. It is generally preferred in patients who have not benefited sufficiently from cancer drugs and cannot undergo surgery. Important criteria for performing the procedure include the patient's age and general condition, liver condition and whether disease has spread elsewhere in the body.
Treatment Prolongs Life in Neuroendocrine Cancers
Radioactive treatments are also used in cancers called neuroendocrine cancers; this treatment is called peptide receptor radionuclide therapy (PRRT). These tumors, abbreviated NET (neuroendocrine tumors), carry peptide receptors called somatostatin and can originate in many organs, including the stomach, pancreas, intestines, thyroid and lungs. Before treatment, PET/CT visualizes the distribution of these receptors in tumors and their amount in tissue. Disease extent and metastases are also identified and the treatment dose planned. Intravenously administered radioactive peptides attach to target cells and emit large amounts of radiation, destroying cancer cells. Patients may need to stay in hospital for a few days afterward. Generally, 3-5 treatment cycles are required. In patients unable to undergo surgery, whose tumors have spread and who do not respond to chemotherapy, the disease may respond in one out of three patients, and progression can be halted in half.
Radioactive Iodine Treatment in Thyroid Cancer
The most widely used and best-known radionuclide treatment is radioactive iodine treatmentfor thyroid cancer, also commonly known as atomic treatment. It has been used for many years with established success and safety. Most patients diagnosed with thyroid cancer require it after surgery. After surgical removal of the entire thyroid gland, radioactive iodine accumulates in remaining cells. Its radiation also eliminates microscopic remnants. In patients with recurrence, it may be repeated at high doses if necessary. Administration is simple: radioactive iodine is taken orally as a capsule or liquid.
Radioactive Treatments Can Be Effective in Certain Childhood Tumors
In treating the childhood tumor neuroblastoma, substances linked to radioactive iodine, called MIBG , can be used. MIBG, which resembles a peptide called norepinephrine used by cancer cells, is linked to radioactive iodine and administered intravenously. This treatment destroys target cancer cells in advanced patients unable to undergo surgery, benefiting one third of patients. Radioactive MIBG treatment may also be effective in neuroendocrine tumors in selected patients.
Use in Lymphoma (Lymph Node Cancer)
Radionuclide treatment can be an option in lymphoma, cancer of the lymph nodes, when other treatments fail. It can be used in selected patients diagnosed with low-grade lymphoma. Linked to radioactive substances such as Yttrium-90 or Iodine-131, CD20 antibodies target antibody targets on cancer cells and destroy the cells by emitting high levels of radiation microscopically. In this disease resistant to other treatments, more than half of cases may respond.
Does Not Exhaust the Patient
Targeted atomic treatments do not exhaust patients or cause extensive damage to noncancerous tissues. In radiotherapy, radiation also affects noncancerous body parts and can damage healthy tissues. Atom-loaded treatments do not irradiate the entire body. Because only the tumor and its surroundings are exposed, healthy tissues are largely protected from radiation's harmful effects. However, necessary precautions must be taken to prevent damage at the sites through which unused radioactive material is excreted.
The Tip of the Iceberg
Nuclear medicine is not used to treat every cancer type. As a rapidly developing treatment method, it can be used with proper patient selection in neuroendocrine tumors, certain lymph cancers, liver cancer, toxic goiter and thyroid cancer, certain childhood tumors and prostate cancer. However, patients must be evaluated from diagnosis by a multidisciplinary team of multiple specialistsand a treatment plan prepared. Considering the advances, the current stage can accurately be described as the tip of the iceberg.
For more comprehensive information, Prof. Dr. Akın Yıldız's websiteis available to visit.
Reader comments
Share your comment
Your name and comment are published only after administrator approval. Your email address is never shown to visitors.
Be the first to comment.