Castration-resistant prostate cancer (CRPC) advances even after a person receives treatment to dramatically lower testosterone levels. Further treatment may aim to prevent cancer from spreading to other parts of the body.

Prostate cancer usually needs normal levels of testosterone to grow. Treatment, such as the surgical removal of the testes or hormone blockade therapy, can severely lower a person’s testosterone levels, which may slow the cancer’s progression.

CRPC occurs when cancer stops responding to castrate levels of testosterone alone. This is testosterone lower than 50 nanograms per deciliter.

It is easier for doctors to successfully treat nonmetastatic cancer, which has not spread from the primary source. So, treatment for CRPC may aim to prevent cancer from metastasizing, or spreading, to other areas of the body such as the bones or lymph nodes.

This article looks at the symptoms, diagnosis, treatment, and outlook for CRPC, as well as guidance for when to speak with a doctor.

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People with early stage, nonmetastatic CRPC do not usually experience symptoms, although they may experience co-occurring conditions that trigger a diagnosis.

A 2016 study suggests that about 60% of people with nonmetastatic CRPC develop metastatic CRPC within 5 years.

Symptoms of metastatic CRPC may include:

According to the Canadian Urological Association, CRPC metastasizes to the bones in 90% of people with the condition. This can cause symptoms such as bone fractures, bone pain, and spinal cord or nerve compression.

Doctors typically diagnose CRPC after a person already has a diagnosis of prostate cancer. Doctors will use various tests to monitor a person’s condition and track the effectiveness of treatment.

They may also use testing results to stage the cancer and determine whether it has metastasized. Tests may include:

  • Prostate exam: A doctor may perform a physical prostate exam, which involves inserting a lubricated finger into the rectum to feel for changes in the prostate.
  • Blood tests: Doctors may check a person’s levels of testosterone and the protein prostate-specific antigen (PSA).
  • Imaging scans: A doctor may order imaging scans such as a CT scan, MRI, PET scan, and bone scan to determine whether the prostate cancer is metastatic and where it has spread to.
  • Biopsy: A doctor may take a small tissue sample from the prostate or a suspected metastatic site in the body. A pathologist will analyze the sample to determine how quickly the cancer cells can grow and spread to other tissue.

Staging and grading

Doctors will use scans to stage CRPC if the cancer has spread throughout the body. They will stage prostate cancer according to the size of the primary tumor, whether cancer has spread to nearby lymph nodes, and whether it has spread to distant areas of the body.

If cancer is nonmetastatic, meaning it has not spread throughout the body, doctors will determine how aggressive the cancer is.

To do this, doctors will look at the doubling time of a person’s PSA level. This can help them determine how quickly cancer may spread and what the best course of treatment may be.

CRPC treatment can vary depending on whether the cancer is metastatic. Treatment for metastatic CRPC may also depend on the size of the primary tumor, how far the cancer has spread, and which areas it has spread to.

Nonmetastatic CRPC

A person has nonmetastatic CRPC if they have rising PSA levels despite having castrate levels of testosterone and if scans show no cancer elsewhere in their body.

Treatment may involve an injection to block testosterone production and a pill to block the androgen receptors.

A doctor may add another form of hormone therapy to the current treatment. This may be an anti-androgen such as enzalutamide or apalutamide.

Alternatively, a doctor may stop treatment with an anti-androgen for some time and monitor a person’s condition for changes.

Metastatic CRPC

Treatment for metastatic CRPC includes:

  • Hormone therapy: Doctors may continue with some form of hormone therapy and may add others, such as an anti-androgen or an androgen synthesis inhibitor like abiraterone.
  • Radiation therapy: Doctors may use radiation therapy on areas the CRPC has spread to that are causing symptoms. This therapy may relieve bone pain, destroy cancer cells, and help with urinary difficulties.
  • Chemotherapy: Doctors may treat symptomatic CRPC with chemotherapy.
  • Targeted therapy: Targeted therapy drugs target specific cells or molecules to stop cancer from growing and spreading. Doctors may use targeted therapy to treat metastatic CRPC in people with certain genetic changes.

Metastatic CRPC usually spreads to the bones. Treatments for metastatic bone cancer include:

  • Corticosteroids: Corticosteroids are a type of drug that reduces inflammation.
  • Pain medication: Pain medications such as opioids, nonsteroidal anti-inflammatory drugs (NSAIDs), and acetaminophen may help relieve bone pain.
  • Bone modifying agents: Bone modifying agents such as bisphosphonates and RANK ligand inhibitors prevent the weakening of the bones.
  • Kyphoplasty: Kyphoplasty is a procedure to stabilize collapsed bones.
  • Radiation therapy: This is a treatment to shrink or destroy cancer cells.

In most people, nonmetastatic CRPC progresses to metastatic CRPC within 3–5 years.

The 5-year survival rate for metastatic CRPC is around 30%. This means about 30% of people with metastatic CRPC survive for at least 5 years after diagnosis.

The 5-year survival rate for people with nonmetastatic prostate cancer in the early stages is much higher, at around 99%.

A person with prostate cancer or a history of prostate cancer should attend regular urologist appointments to monitor for changes that may indicate CRPC.

Anyone who has nonmetastatic prostate cancer and is receiving treatment should urgently contact their doctor if they experience symptoms of metastatic CRPC, such as those listed above.

A person may wish to speak with their doctor about screening for prostate cancer, which can help doctors identify the condition in the early stages.

Castration-resistant prostate cancer (CRPC) is prostate cancer that no longer responds to castrate levels of testosterone alone.

A reduction of testosterone typically slows the progression of prostate cancer. However, in CRPC, the cancer continues to grow even when testosterone levels are extremely low.

A different treatment, such as medication to block androgen receptors, may be necessary to shrink the cancer.

CRPC progresses to metastatic CRPC in most people. It typically spreads to the bones and can cause symptoms such as bone pain and fractures.

Treatment may include hormone therapy, radiation therapy, chemotherapy, and targeted therapy.