Many medical centers across the nation are researching the causes and treatment of lung carcinoid tumors. This is a challenging disease to study because it is not common. But each year, scientists find out more about what causes the disease and how to improve treatment.
Genetics
Researchers have made great progress in understanding how certain changes in DNA can cause normal cells to become cancerous. DNA is the molecule that carries the instructions for nearly everything our cells do. We usually look like our parents because they are the source of our DNA.
However, DNA affects more than how we look. Some genes (parts of our DNA) contain instructions for controlling when our cells grow and divide. Certain genes that cause cells to grow and divide into new cells are called oncogenes. Others that slow down cell division or cause cells to die at the right time are called tumor suppressor genes. Cancers can be caused by DNA mutations (defects) that turn on oncogenes or turn off tumor suppressor genes. Researchers have characterized many of the DNA changes in lung carcinoids in the past few years. Continued research in understanding these changes will lead to new tests for earlier diagnosis and new drugs for more effective treatment.
Diagnosis
Because the outlook and treatment of lung carcinoids and other types of lung cancer are very different, accurate diagnosis is important. Researchers have made great progress in developing tests that can detect specific substances found in the cells of carcinoid tumors but not other lung cancers. Most of these tests treat tissue samples with special man-made antibodies in the lab. The antibodies are designed to recognize specific substances in certain types of tumors.
Treatment
Doctors are learning how to treat lung carcinoids more effectively. For example, newer surgical techniques allow doctors to remove parts of the lung through smaller incisions, which can result in shorter hospital stays and less pain for patients. And new radiation therapy techniques help doctors focus the radiation more precisely on tumors, lowering the amount of radiation that normal tissues get and reducing side effects.
Metastatic carcinoid tumors remain hard to treat. Most carcinoid tumors grow fairly slowly. Because standard chemotherapy drugs work by attacking quickly growing cells, they are not very effective against carcinoid tumors. Newer drugs called targeted therapies may prove to be more effective against carcinoids.
Targeted therapy is a newer type of cancer treatment that uses drugs or other substances to identify and attack cancer cells while doing little damage to normal cells. These therapies attack the cancer cells' inner workings -- the programming that makes them different from normal, healthy cells. Each type of targeted therapy works differently, but all alter the way a cancer cell grows, divides, repairs itself, or interacts with other cells.
Two targeted therapy drugs, sunitinib (Sutent®) and everolimus (Afinitor®), have recently been shown in studies to be helpful in treating neuroendocrine tumors that start in the pancreas. Studies of these drugs in carcinoid tumors (which are a type of neuroendocrine tumor) are in progress
.Angiogenesis inhibitors affect the growth of new blood vessels (angiogenesis), which tumors need to grow larger. Some of these drugs are already used to treat other types of cancer and are now being studied for use against carcinoid tumors. Examples of these drugs include thalidomide (Thalomid®), bevacizumab (Avastin®), and pazopanib.
Another group of targeted drugs being studied for use against carcinoid tumors are known as mTOR inhibitors. Examples include temsirolimus (Torisel®) and everolimus (Afinitor®).
Another new treatment that has been studied is 90Y-edotreotide. This pairs a drug similar to octreotide with a radioactive atom (a form of yttrium). The drug binds to the carcinoid cells, delivering the radiation to those cells and lessening the effect on normal cells. This treatment has helped patients with advanced carcinoid tumors that were no longer responding to other treatments.
These and other new drugs are now being studied in clinical trials.
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