Targeted therapies are designed to treat only the cancer cells and minimize damage to normal, healthy cells. Cancer treatments that "target" cancer cells may offer the advantage of reduced treatment-related side effects and improved outcomes. Traditional treatments for cancer are chemotherapy and radiation. While these are very effective, they cause significant side effects, have a negative effect on the quality of life, and can be almost intolerable for some patients.
These traditional cancer treatments cannot distinguish between cancer and healthy cells, numerous healthy cells can be destroyed, resulting in side effects that include fatigue, hair loss, and vulnerability to infection. The destructive nature of treatment often leads patients to give up and refuse to have another round, and make things difficult for their caregivers.
However, we are learning more about cancer all the time. With some types of cancer, we know exactly what is causing the disease and thus how to stop it. Enter targeted therapy. Targeted therapy endeavors to kill only the tumor, with minimal effect on the surrounding tissue or the overall system. This results in greater effectiveness and fewer side effects. More and more patients are benefitting from these approaches.
How Does Targeted Therapy Work?
Targeted therapy uses a drug or substance that blocks the growth of cancer. Doctors identify certain biomarkers and target them. Biomarkers are specific molecules that exist only in the tumor's cells and are not present in healthy tissue. They differ significantly from drugs used in chemotherapy; rather than killing the cancer, the goal is to prevent it from growing further. It is part of the foundation of precision medicine and is a type of treatment that typically targets proteins that control how cancer cells grow, divide, and spread.
Targeted therapies can:
- Cut off the hormones your cancer is using to grow.
- Encourage cell death in cancer cells.
- Deliver cell-killing substances to specific cancer cells.
- Signal the blood to stop creating blood vessels that your tumor needs to grow.
- Slow and stop the growth of cancer cells.
- Trigger your immune system to target and attack cancer cells.
The choice of targeted therapy depends on the type of tumor, not its location. In the past, lung cancer and breast cancer, for example, have been seen as very different diseases, but targeted therapy changes this. The same treatment might be used for colon and stomach cancer, providing the tumors use the same biomarkers.
What is the Targeted Therapy Treatment Process?
The treatment process depends on the specific drug being used. There are two ways targeted drugs are normally given:
- IV. In this process, the drug is introduced directly to your bloodstream through a catheter. It may be an IV push (which takes a few minutes) or an infusion (which can take several hours). You may be given a central venous catheter so they don't have to stick you with a needle each time. The drug is given in a cancer treatment clinic.
- Oral. Some targeted drugs can be taken orally, just like other medicines. They may be a pill, a capsule, or a liquid. You will be given specific instructions on exactly when to take your treatment and the dosage. Generally, these medicines have to be taken at the exact same time.
Oral cancer drugs should be treated as hazardous and kept well away from children and pets. Before getting targeted therapy, you may need a biopsy to test what drugs the cancer is going to best respond to. There may be other criteria, such as unsuitability for surgery.
Types of Targeted Therapies
Targeted therapies fall into a number of different types, which may act in different ways. Different cancers tend to require a different approach. Here are the seven basic types of targeted therapy:
- Signal transduction inhibitors. These interfere with the false signal cancer cells get that cause them to divide continuously.
- Hormone therapies. These are used on hormone-sensitive tumors because they slow or stop the growth of them by preventing the body from producing hormones. Hormone-related breast and prostate cancers often respond well to these.
- Apoptosis inducers cause cancer cells to undergo a process of controlled cell death called apoptosis. Apoptosis is how the body gets rid of abnormal cells; cancer cells are sneaky and avoid this. The drug helps the body target them for removal.
- Angiogenesis inhibitors. These block the growth of new blood vessels to tumors, preventing their growth. These inhibitors are used in cancers that tend to grow larger tumors.
- Gene expression modulators modify the function of proteins that play a role in controlling gene expression. Some cancers are caused when genes are expressed incorrectly; modulators affect proteins that play a role in this, turning off (or on) the problem genes.
- Immunotherapy triggers the immune system to destroy cancer cells. This includes monoclonal antibodies, which recognize specific molecules on the surface of cancer cells. (Cancer vaccines can also fit into this area).
- Monoclonal antibodies that deliver toxic molecules. Monoclonal antibodies can also be used to carry a toxic molecule into the cancerous tumor, without affecting other tissue.
The overall idea is that the therapy must affect only the cancer cells.
How Often Do You Need Targeted Therapies?
The frequency and length of targeted therapy treatment will depend on your cancer and how well you respond to treatment. Treatment may be every day, every week, or every month. You might also be given the treatment in cycles; a period of treatment followed by a break.
You must follow all of your doctor's instructions and go to all follow-up appointments. Your cancer care team will work with you for your individualized cancer treatment plan.
What are the Side Effects?
Targeted therapies have far fewer side effects than traditional chemotherapy or radiation therapy. However, they are not completely free of side effects and problems. Common side effects include:
- Liver problems, including hepatitis
- Skin problems, such as rashes, dry skin, changes to nails and depigmentation (but generally not loss) of hair.
- Issues with wound healing and blood clotting.
- Elevated blood pressure.
There may be other side effects with the specific drug you are receiving; check with your oncologist.
How Do You Know if it is Working?
You will be seeing a lot of your doctor during the process, and they will assess whether the treatment is working.
Your doctor may order a variety of medical tests, including scans of the tumor and blood tests to help determine whether or not it is working. Doctors will look at measures such as whether the tumor is growing or shrinking and how much genetic material from the tumor is in your blood.
Questions to Ask your Doctor
If your oncologist is recommending targeted treatment, you should ask a few questions. Here are some suggestions:
- How do you know that this is the right targeted treatment for me?
- What are the specific side effects of the drug you are recommending?
- How new is this drug?
- What are the outcomes like for patients in a similar situation?
You should make sure you have all of the information you need before agreeing to treatment. This is particularly important if your doctor is suggesting enrollment in a clinical trial (there are clinical trials for new targeted therapies going on all the time).
At Compass Oncology, we are finding many of our patients benefit from targeted therapy. It's a new tool we can use to improve patient outcomes, although it is not suited to everyone. Talk to us to find out more and schedule a consultation with one of our oncologists.