What Medications Are Used for Advanced Prostate Cancer?
Just like any other cancer, prostate cancer has the ability to metastasize, or spread, throughout the body. How far a cancer has spread, and how quickly it spreads are often designated by the stage of the cancer or by its level of aggressiveness. Some cancers are very slow growing, taking many years to travel beyond their initial location. Other cancers can spread rapidly, spreading to other areas of the body very quickly. Talk to your healthcare provider for further information.
Often, when prostate cancer cases are diagnosed at an early stage they can take years to travel beyond the prostate. There can still be a proportion of men who will be initially diagnosed with advanced or aggressive prostate cancer. In these cases, the cancer may metastasize beyond the prostate into the lymph nodes, or to other organs within the body.
What is advanced prostate cancer?
One of the places the cancer can metastasize to is the bones. At this point, the cancer is typically non-responsive to hormone therapy as well as to many other treatment options. In many cases, bone metastases are inoperable and can cause debilitating pain. Treatment options during this time are typically palliative in nature, meaning that they aren’t attempting to cure the cancer, but rather are designed to provide symptom relief and increase the quality of life.
Below is a summary of treatment options designed for advanced prostate cancer, or prostate cancer that has spread to the bones. While sometimes these could be used only for palliative care, it is important to note that in some cases, these can be used in combination with other treatment options, such as radiation, surgery, or chemotherapy, that is intended to treat the cancer. Patients should take their medication as prescribed by their doctor. Patients should talk to their doctor if they have any questions, or if they have questions regarding their medication regimen. Before starting treatment for advanced prostate cancer, patients should tell their doctor about all medications (prescription and over-the-counter), herbal supplements, and vitamins they are taking.
Zytiga® (abiraterone acetate) with prednisone
Zytiga® (abiraterone) is a CYP17 inhibitor that is used in combination with prednisone to treat certain individuals with metastatic castration-resistant prostate cancer. It is also approved with prednisone, for metastatic high-risk castration-sensitive prostate cancer (CSPC). Abiraterone and the prednisone accompanying it are oral dosage forms taken by mouth. Patients should discuss their exact dosing regimen and instructions with their doctor. Individuals taking abiraterone should also be monitored for changes in the amount of mineralocorticoids and adrenocorticoids (steroid hormones) in their blood while on the medication, as well as for any signs of changes in liver functioning.
Zometa® (zoledronic acid)
Zometa® (zoledronic acid) is a bisphosphonate medication that is indicated for the treatment of bone metastases and hypercalcemia of malignancy, otherwise known as excess calcium in the body as a result of cancer that has spread to the bones. Zoledronic acid slows down the bone destruction process, also called bone resorption. When cancer metastasizes, it can destroy bones outweighing bone growth. When bones are broken down too quickly, excess calcium is released into the blood and our bones get weaker. This can lead to hypercalcemia, or too much calcium in the blood, as well as to bone pain and fractures. By slowing down the bone destruction process zoledronic acid can reduce bone pain and decrease the risk of fractures. Zoledronic acid also helps reduce hypercalcemia and its symptoms, including nausea and vomiting, loss of appetite, headaches, and kidney stones.
Zoledronic acid is administered as an intravenous (IV) injection with its most common side effects including vomiting, constipation, fever, anemia, fatigue, and nausea. This is not an exhaustive list of all potential side effects of zoledronic acid. Talk to your healthcare provider or pharmacist for further information. Individuals taking zoledronic acid should also be monitored for severe musculoskeletal pain, destruction of the jaw, changes in kidney function, breathing problems, and femoral bone fractures.1
Xgeva® (denosumab) is a human monoclonal antibody that acts as a RANK ligand inhibitor that helps prevent skeletal-related events, such as bone fractures, that are a result of cancer spreading to the bones, and hypercalcemia of malignancy. Denosumab is also on the market under the brand name Prolia, which is used for certain cases of osteoporosis (bone loss), as well as for increasing bone mass in some breast cancer, and non-metastatic prostate cancer, patients receiving specific treatments who are also at high risk of bone fracture. Xgeva inhibits osteoclast cells. Our bodies are continuously building and destroying our bones in a balanced process that keeps us healthy and strong. Cells in our body called osteoclasts regularly break down bone to release minerals, like calcium into our bloodstream.
In order for new osteoclasts (the cells that break down bone) to be made, RANK-L needs to be activated. Xgeva binds to the RANK-L, blocking it from the receptor, and preventing the activation process needed to make mature osteoclasts. By preventing osteoclasts from functioning normally the bone-building process can catch up. When our body builds bone, it utilizes calcium in the bloodstream, keeping our nutrients in balance, as well as increases our skeletal stability. This can help decrease the risk of fractures.
Xgeva is administered as a subcutaneous (under the skin) injection in the upper arm, upper thigh, or abdomen. The most common side effects of Xgeva include fatigue, nausea, shortness of breath, diarrhea, and headache. This is not an exhaustive list of all potential side effects of Xgeva. Talk to your healthcare provider or pharmacist for further information. Individuals taking Xgeva should also be monitored for hypocalcemia (too little calcium in the blood), and destruction of the jaw.2
Corticosteroid medications, also known as steroids, are a class of drugs designed to mimic naturally occurring corticosteroids produced by the adrenal cortex above the kidneys. Corticosteroids carry out a wide range of functions in the body. Some of these functions can aid in the relief of bone pain, inflammation, and nausea that comes along with cancer or the treatment of cancer. Common corticosteroids used to treat prostate cancer and side effects of treatment include prednisone and dexamethasone, among many others.
For the treatment of prostate cancer, specific corticosteroids can be prescribed in combination with other therapies (such as chemotherapy, radiation, or palliative care options) or used to aid in symptom or side-effect management. Examples of symptoms that may be alleviated as a result of treatment with corticosteroids include nausea, vomiting, sensitivity reactions to radiation or chemotherapy, bone pain, and back pain. Steroids can also help increase your appetite when your current treatment options are reducing it or making you nauseous.
The most common side effects of taking corticosteroids include swelling or fluid retention, high blood pressure, mood or behavior changes, weight gain, increased appetite, and changes in blood glucose (sugar) levels. Corticosteroid injections may also cause injection site reactions. This is not an exhaustive list of all potential corticosteroid side effects. Talk to your healthcare provider or pharmacist for further information. Individuals taking corticosteroids should also be monitored for severe mood changes, severe infections, hormonal imbalances, high blood pressure, and changes in vision. Corticosteroids can be given orally or through an injection.3,4
External radiation therapy
External radiation therapy, also called external beam therapy (EBT), involves focusing a beam of high-energy radiation (or X-rays) onto the tumor from the outside. The location of the tumor is determined by imaging procedures.
Radiation therapy may be used with the intent to cure or shrink an individual’s cancer, however, external beam radiation to treat cancer that has metastasized to the bones is typically for pain relief. Targeting a malignant tumor on a bone, including on the spine, before it does too much damage, can lead to pain relief, as well as the prevention of future fractures and instability. Preventing fractures and skeletal instability can improve an individual with late-stage cancer’s quality of life.
Your doctor will help you determine what treatment schedule is best for you. Some individuals may only need one to two EBT treatments, while others may need more treatments. Your doctor will also closely monitor you during treatment and regularly afterwards. Side effects of EBT can vary with the location of the radiation, dosage given, and amount of times treated. Consult your provider for more information on your specific case.3
Radiopharmaceuticals belong to a class of medications that are considered systemic radiation therapies. These medications contain radioactive substances that help alleviate bone pain when cancer metastasizes to the bones. The most common radiopharmaceuticals used in the treatment of prostate cancer-related bone pain include Strontium-89 (MetastronTM), Samarium-153 (Quadramet®), and Radium-223 (Xofigo®). These drugs are given as intravenous (IV) injections. Radiopharmaceuticals are typically indicated for individuals with prostate cancer that has metastasized to the bones and has accompanying pain. Radium-223 may be used for patients with castrate-resistant prostate cancer (prostate cancer that is not responding to treatment to lower the body’s level of testosterone) that has spread (metastasized) only to the bones and is causing symptoms, and has not spread to other areas of the body. Radium-223 may be a part of a patient's prostate cancer treatment to help them live longer, as opposed to only helping to relieve pain.
The radioactive elements in radiopharmaceuticals are attracted to areas in the body that are experiencing rapid cell turnover, such as where cancer has metastasized to the bones. Radiopharmaceuticals selectively deposit in the bone lesions, releasing local radiation, leading to pain relief. It may take a week or more to feel a reduction in pain.
Common side effects of certain radiopharmaceuticals include, but are not limited to, vomiting, diarrhea, nausea, swelling of the limbs, low blood cell counts, dehydration, and injection site reactions. When taking radiopharmaceuticals, you may be provided with strict safety guidelines that will help protect yourself and those around you from radiation-related risks. It is important to follow these guidelines exactly as you are instructed.4-6 Talk to your healthcare provider or pharmacist for further information.