Treatment Options for Metastatic Prostate Cancer

What Is Metastatic Prostate Cancer?

Prostate cancer begins in the prostate – a gland in males that makes seminal fluid – when cells in that gland mutate and start to grow rapidly. Prostate cancers are usually adenocarcinomas, which develop from glandular cells. These cancers can develop slowly or quickly but generally grow gradually without causing symptoms in their early stages. Prostate cancer is more likely to occur in African American men over the age of 50 and in men with a family history of prostate cancer.

While many cases of prostate cancer are cured or controlled with initial treatment, prostate cancer can spread to other areas of the body, such as the bone or liver. When this occurs, it is termed metastatic prostate cancer. When prostate cancer metastasizes, or spreads, patients can notice symptoms such as bone pain or even neurological symptoms, such as numbness in the extremities or problems with bowel or bladder control, caused by tumors pressing on and interfering with the function of nerves.

Diagnosing Metastatic Prostate Cancer

Prostate cancer often does not cause symptoms during its early stages, making it hard to diagnose without screening. Most prostate cancers are found due to screening.

Screening for prostate cancer typically involves analyzing a sample of blood for a protein known as prostate-specific antigen (PSA). Sometimes, physicians also will perform a digital rectal exam (DRE), in which a doctor feels the prostate gland by briefly putting a gloved, lubricated finger into the patient’s rectum. Different medical organizations have varying recommendations regarding the age at which men should begin PSA screening. Those recommendations often endorse starting screening at an earlier age – such as in the early 40’s – for men at elevated risk for prostate cancer, such as men of African ancestry and those with a family history of the disease.

Other medical groups even advise against measuring PSA in men without symptoms. These recommendations arise from the fact that PSA levels can be elevated for many reasons other than prostate cancer, such as urinary tract infections or age-related, benign enlargement of the prostate. Screening by PSA can lead to unnecessary further testing, exposing patients to low doses of radiation with imaging studies or a small risk of infection from having a biopsy. It is important for men to talk with their primary care provider about their risk factors for prostate cancer, the benefits and risks of screening, and the approach that makes sense for them.

Diagnostic Tests and Imaging

If a man has an elevated PSA level or concerning findings on DRE, his doctor may refer him to a urologist for further evaluation. This may include:

• Prostate biopsy: In this procedure, a physician removes a small sample of prostate tissue to examine it under a microscope and determine if the cells are cancerous.
• Transrectal ultrasound (TRUS): A small probe about the width of a finger is lubricated and placed in the rectum to obtain images of the prostate. Physicians often use TRUS when performing a prostate biopsy to determine their choice of biopsy sites.
• Magnetic resonance imaging (MRI): MRIs provide detailed images of the prostate and nearby areas to help determine if cancer is present and, if so, its exact location and extent.
• Multiparametric MRI:This innovative MRI technique helps the physician better identify possible cancerous areas in the prostate and get an estimate of how fast the cancer might grow.
• Computed tomography (CT) scan: A CT scan uses X-rays to create detailed images of the body. These scans can help determine if prostate cancer has spread into nearby lymph nodes.
• Positron emission tomography (PET) scan: This sophisticated imaging method also provides detailed information on the presence of any cancerous lesions. A relatively new refinement of PET scanning involves injecting the patient with a radioactive substance that travels to areas of the body where a protein known as prostate-specific membrane antigen (PSMA) is present. Because PSMA is expressed by prostate cancer cells, mapping its location in the body can show where the cancer has spread.
• Genetic testing to identify the mutations driving the prostate cancer. This information can help shape treatment plans.

These diagnostic tests help the care team determine the correct diagnosis and, if cancer is present, the stage of the cancer.

Staging the Cancer

When a diagnosis of prostate cancer is made, the disease is then categorized by stage. Staging is based on the location and extent of the cancer and helps determine the best treatment approaches. In the “TNM” approach to staging, described below, the stages of prostate cancer range from I to IV. Stage I describes cancer contained to the prostate gland itself, while stage IV signifies prostate cancer that has spread to the lymph nodes (Stage IVA) or to other areas of the body (Stage IVB). Physicians use a number of different means of assessing and describing prostate cancer, including:

• The TNM staging system: This system categorizes the cancer by characterizing the size and location of the tumor (T), the presence or absence of cancer in lymph nodes (N), and the presence or absence of metastasis (M), or spread, elsewhere in the body.
• Gleason score: This score is based on the extent to which cancerous tissues obtained at biopsy or surgical removal of the prostate look similar to or different from healthy prostate cells.
• Stage groups: In this approach, a tumor is assigned a grade from 1 to 5, with grade 1 representing cancers most likely to grow and spread slowly, and grade 5 representing cancers most likely to grow and spread quickly.

Obtaining an accurate diagnosis and determining the cancer’s stage is critical to determine the treatment options that are most suitable for each patient.  

Treatment Approaches

When medical oncologists or urologists consider the best approach to treating a patient with metastatic prostate cancer, they weigh factors including where and to what extent the cancer has spread, the patient’s age and overall health, and whether the cancer is considered “hormone sensitive” or “castration resistant.” Many prostate cancers, particularly earlier-stage cancers, need male sex hormones such as testosterone to grow. As a result, doctors often prescribe medications known as androgen deprivation therapy (ADT) to block the production of these hormones. When men with metastases generally continue to respond to these treatments, they are said to have metastatic hormone-sensitive prostate cancer, or mHSPC. Men whose metastatic cancer continues to progress despite having testosterone levels below 50 nanograms per deciliter (ng/dL) are said to have metastatic castration-resistant prostate cancer, or mCRPC, which is a particularly advanced stage of the disease. Note: The term “castration-resistant” was introduced decades ago, at a time when physicians would surgically remove a man’s testicles, which are responsible for the majority of the testosterone produced by the body, to lower his testosterone levels. That approach has been almost entirely abandoned today in favor of administering ADT therapy to lower testosterone to below 50 ng/dL, which is considered “castration” level. The term remains in use although the approach has changed.

Conventional treatment options for metastatic prostate cancer include:

Radiation Therapy and Radiopharmaceutical Therapy

Radiation therapy is a common treatment for prostate cancer that uses high-energy rays to attack cancer cells or slow their growth. Both external beam and internal radiation may be used, and occasionally they are used sequentially. Radiopharmaceuticals – medications that emit radiation – also are used in mCRPC. One such medication is used in patients with bone metastases and acts at the site of rapid bone turnover. Another is used in conjunction with PET PSMA scans and acts at sites identified by that testing.

Hormone Therapy

Hormone therapy helps disrupt the body’s ability to make the hormones that fuel the growth of prostate cancer. In addition to first-generation hormonal therapies – the ADT mentioned earlier – second-generation androgen receptor inhibitors are used in metastatic prostate cancer to slow the progression of cancer and prolong survival.

Chemotherapy

Chemotherapy works to kill cancer cells and decrease tumor size, slowing the spread and often relieving the symptoms of metastatic prostate cancer. Docetaxel and cabazitaxel are the two forms of chemotherapy used most often in metastatic prostate cancer.

Immunotherapy

Immunotherapy works by strengthening the patient’s immune system, allowing it to identify and kill cancer cells. One immunotherapy has been used to treat mCRPC for almost 20 years, while newer immunotherapy approaches approved for use in certain patients with metastatic prostate cancer include checkpoint inhibitors and cellular immunity drugs. This option can work well for patients with metastatic prostate cancer that is hormone-resistant.

Targeted Therapy

Targeted therapy uses drugs that act against specific mutations on cancer cells or that interfere with specific cancer cell growth processes. One common type of targeted therapy used to treat metastatic prostate cancer is PARP inhibitors, which target the poly (ADP-ribose) polymerase (PARP) enzymes that play a role in DNA repair.

While surgery – particularly a procedure called radical prostatectomy – is a commonly employed approach to treating early-stage prostate cancer, it typically is not a part of the treatment plan when a man’s cancer already has metastasized at the time of diagnosis. Hormone therapy is often the initial treatment administered for metastatic disease because it acts throughout the body.  

Clinical Trials and Experimental Treatments

Emerging therapies are evaluated in clinical trials, which evaluate the safety and efficacy of potential treatments work in volunteer patients. Clinical trials help science and cancer treatment evolve while providing patients with access to innovative treatments at little or no cost. Clinical trials are governed by strict ethical standards and have stringent patient safety protocols in place. Before enrolling in a clinical trial, patients must be informed of the known potential risks and benefits of a treatment so that they can give their informed consent if they choose to participate.

Regional Cancer Care Associates participates in roughly 300 clinical trials to help advance cancer care and outcomes.

Integrative Approaches to Prostate Cancer Care

In addition to medical therapies, patients can take other steps that may help enhance their overall health and sense of well-being. These steps can include:

Diet and Nutrition

Many medical specialists recommend that patients with prostate cancer eat a plant-based diet or increase their intake of fish, fruits, veggies, and soy, while eating less red meat, processed and fried foods, and dairy.

Exercise and Lifestyle Modifications

Both smoking and obesity are harmful to overall health. Therefore, making lifestyle changes such quitting smoking and losing weight through diet and exercise can be helpful and may enhance a patient’s ability to fight cancer and deal with any side effects of its treatment.

Some patients also make use of complementary therapies alongside their conventional treatments, such as acupuncture and meditation. Men with metastatic prostate cancer should consult their medical oncologist or urologist before beginning any complementary or alternative treatment. In particular, they should not take any supplement, herbal preparation, or other substance without first talking with their doctor.

Palliative Care for Prostate Cancer

If a patient has an advanced stage of prostate cancer or cancer that is not responding to treatments, prostate cancer specialists may recommend palliative care. Palliative care involves specialized medical care that helps treat the symptoms of prostate cancer, relieve the side effects of treatments, and provide comfort. It also can entail providing emotional and psychological support to those fighting cancer, as well as enhancing quality of life.

Find Compassionate Care for Prostate Cancer at RCCA

Men with metastatic prostate cancer require high-quality cancer treatment. Regional Cancer Care Associates (RCCA) offers a wide range of evidence-based prostate cancer treatments, including hormonal therapy, immunotherapy, targeted therapy, and chemotherapy to treat metastatic prostate cancer. With more than 20 locations throughout New Jersey, Connecticut, Maryland, and the Washington, D.C., area, RCCA provides world-class cancer care close to home. Request an appointment today with an oncology specialist to discuss treatment options.