Introduction
Advanced prostate cancer has been addressed with several names over the years, like hormone-resistant prostate cancer (HRPC) and androgen-insensitive prostate cancer (AIPC). The term castration-resistant prostate cancer was introduced more recently when it was recognized that the production of intracrine or paracrine androgen plays an important role in the prostate cancer cell's resistance to testosterone suppression therapy.
Prostate cancer requires testosterone to expand. Therefore, the treatment aims to decrease the supply of the male sex hormone, mostly made by the testicles. The male sex hormones are called androgen deprivation therapy. Hormone therapy often involves medications, known as chemical or medical castration, because it decreases the sex hormones. Sometimes, patients choose surgical castration, which involves the removal of the testicles. A study on 25,000 men documented that around five percent opted for surgical castration. If cancer keeps expanding, even when testosterone production is low, which indicates the presence of castration-resistant prostate cancer (CRPC).
What Is Castration-Resistant Prostate Cancer?
Castration-resistant prostate cancer is a type of advanced prostate cancer. It cannot be cured. However, the life span can be prolonged through treatment.
Castration-resistant prostate cancer leads to the progression of pre-existing disease, continuous rise in serum prostate-specific antigen (PSA) levels, and new metastases. Prostate cancer does not result in death in most cases. However, it is more fatal in American men than any other type of lung cancer except lung cancer.
What Are the Types of Castration-Resistant Prostate Cancer?
The types of castration-resistant prostate cancer include
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Metastatic.
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Non-metastatic.
1. Metastatic Castration-Resistant Prostate Cancer: It occurs when the prostate cancer spreads or metastasizes to other body parts like the bones and lymph nodes. In this type of cancer, the standard hormone therapy does not help because cancer grows without being affected by testosterone levels. Almost all individuals with metastatic prostate cancer will eventually suffer from a castration-resistant form responsible for most of the deaths from prostate cancer.
2. Non-metastatic Castration-Resistant Prostate Cancer: It occurs when cancer does not spread and is present only in the prostate, and the cancerous growth does not respond to hormone treatments.
What Are the Symptoms of Castration-Resistant Prostate Cancer?
In the case of non-metastatic castration-resistant prostate cancer, there might be no signs or symptoms noticed. On the other hand, metastatic castration-resistant prostate cancer symptoms depend on the tumor size and its metastasis to the lungs, rectum, and other organs and tissue.
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Pain during urination.
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Blood in the urine.
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Unexplained weight loss.
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Weakness.
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Bone ache.
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Shortness of breath.
How Is Castration-Resistant Prostate Cancer Diagnosed?
The doctor can use the methods below to identify whether prostate cancer has turned
castration-resistant.
1. Blood Test: If the patient is undergoing hormone therapy, the serum testosterone level should be less than 50 nanograms per deciliter. It prevents the increase of prostate-specific antigen (PSA) levels. The doctor checks the PSA levels regularly to be sure it remains low. A rise in PSA level is the primary sign that prostate cancer has become castration-resistant.
2. Imaging Tests: The following imaging tests can be performed by the doctor to detect the presence of castration-resistant prostate cancer:
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Computed tomography scan (CT scan).
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Bone scans.
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Magnetic resonance imaging (MRI) scans.
How Can Castration-Resistant Prostate Cancer Be Treated?
The treatment is based on the type of cancer:
1. Non-metastatic Castration-Resistant Prostate Cancer: If the castration-resistant prostate cancer has not yet spread outside the prostate, the main goal of the treatment is to delay that spread. The treatment also aims to increase life expectancy and help lead a normal life. This treatment protocol can be complex and involves androgen deprivation therapy (ADT) to keep the testosterone level low. The rise of testosterone levels might lead to further progression of cancer. Androgen deprivation therapy (ADT) can affect heart health, further complicating the treatment. It can also increase the risk of falls and fractures, affecting cognition and interfering with the ability to have sex.
2. Metastatic Castration-Resistant Prostate Cancer: If castration-resistant prostate cancer has spread to other body parts like bones, certain treatment options are available. The major goal of therapy is to relieve the symptoms and reduce cancer growth. The patient is kept on androgen deprivation therapy (ADT) to control the prostate cancer cells that still might respond to it. Otherwise, the testosterone levels may increase and cause tumor growth.
Treatment options available include:
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Chemotherapy.
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Immunotherapy helps the immune system to fight cancer. It is often used in those with few or no prostate cancer symptoms.
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Radiation attacks cancer cells that spread to the bones.
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Novel hormone therapies also help expand lifespan.
With treatment, men with castration-resistant prostate cancer may live a long and improved life. However, most patients usually succumb to their disease, and better treatment options are required. For patients with metastatic castration-resistant prostate cancer, Docetaxel-based chemotherapy is recommended. Zoledronic acid is also recommended to reduce the risk of bone complications. Other treatments presently under investigation might soon add to the therapeutic options available. Various new agents are now being studied in a pre-chemotherapy setting, in combination with Docetaxel as well as in the post-Docetaxel setting.
What Is the Prognosis of Castration-Resistant Prostate Cancer?
The prognosis of castration-resistant prostate cancer is associated with various factors, including:
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Performance status to the treatment.
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The extent of disease on bone scan.
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Presence of bone pain.
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Serum alkaline phosphatase levels.
Bone metastases (spread of cancer cells to the bone) are seen in 90 percent of men with castration-resistant prostate cancer and can lead to significant morbidity involving pain, spinal cord compression, pathologic fractures, and bone marrow failure. Paraneoplastic effects also occur commonly, like anemia, hypercoagulability, weight loss, increased susceptibility to infection, and fatigue.
Conclusion
Advanced castration-resistant prostate cancer (CRPC) is a serious problem that requires a multidisciplinary approach. The major objective is maintaining the quality of life by providing supportive care. It is essential to build on the currently available data to improve the outcome in these poor-prognosis patients further. Hopefully, the near future will lead to more novel treatment protocols for patients with castration-resistant prostate cancer. Castration-resistant prostate cancer is a spectrum of diseases varying from patients without metastases or symptoms to patients with metastases and significant cancer-related problems.
