Prostate cancer is a disease in which malignant (cancer) cells form in the tissues of the prostate.

The prostate is a gland in the male reproductive system. It lies just below the bladder (the organ that collects and empties urine) and in front of the rectum (the lower part of the intestine). It is about the size of a walnut and surrounds part of the urethra (the tube that empties urine from the bladder). The prostate gland makes fluid that is part of the semen.

Prostate cancer is most common in older men. In the U.S., about 1 out of 8 men will be diagnosed with prostate cancer.

Signs of prostate cancer include a weak flow of urine or frequent urination.

These and other signs and symptoms may be caused by prostate cancer or by other conditions. Check with your doctor if you have any of the following:

• Trouble starting the flow of urine.
• Frequent urination (especially at night).
• Trouble emptying the bladder completely.
• Weak or interrupted ("stop-and-go") flow of urine.

When prostate cancer is detected in an advanced stage, symptoms may include:

• Pain in the back, hips, or pelvis that doesn't go away.
• Shortness of breath, feeling very tired, fast heartbeat, dizziness, or pale skin caused by anemia.

Other conditions may cause the same symptoms. As men age, the prostate may get bigger and block the urethra or bladder. This may cause trouble urinating or sexual problems. The condition is called benign prostatic hyperplasia (BPH), and although it is not cancer, surgery may be needed. The symptoms of benign prostatic hyperplasia or of other problems in the prostate may be like symptoms of prostate cancer.

Tests that examine the prostate and blood are used to diagnose prostate cancer.

The following tests and procedures may be used:

• Physical exam and health history: An exam of the body to check general signs of health, including checking for signs of disease, such as lumps or anything else that seems unusual. A history of the patient’s health habits and past illnesses and treatments will also be taken.
• Digital rectal exam (DRE): An exam of the rectum. The doctor or nurse inserts a lubricated, gloved finger into the rectum and feels the prostate through the rectal wall for lumps or abnormal areas.
• Prostate-specific antigen (PSA) test: A test that measures the level of PSA in the blood. PSA is a substance made by the prostate that may be found in higher than normal amounts in the blood of men who have prostate cancer. PSA levels may also be high in men who have an infection or inflammation of the prostate or BPH (an enlarged, but noncancerous, prostate).
• PSMA PET scan: An imaging procedure that is used to help find prostate cancer cells that have spread outside of the prostate, into bone, lymph nodes, or other organs. For this procedure, a cell-targeting molecule linked to a radioactive substance is injected into the body and travels through the blood. It attaches to a protein called prostate-specific membrane antigen (PSMA) that is found on the surface of prostate cancer cells. A PET scanner detects high concentrations of the radioactive molecule and shows where the prostate cancer cells are in the body. A PSMA PET scan may be used to help diagnose prostate cancer that may have come back or spread to other parts of the body. It may also be used to help plan treatment.
• Transrectal ultrasound: A procedure in which a probe that is about the size of a finger is inserted into the rectum to check the prostate. The probe is used to bounce high-energy sound waves (ultrasound) off internal tissues or organs and make echoes. The echoes form a picture of body tissues called a sonogram. Transrectal ultrasound may be used during a biopsy procedure. This is called transrectal ultrasound guided biopsy.
• Transrectal magnetic resonance imaging (MRI): A procedure that uses a strong magnet, radio waves, and a computer to make a series of detailed pictures of areas inside the body. A probe that gives off radio waves is inserted into the rectum near the prostate. This helps the MRI machine make clearer pictures of the prostate and nearby tissue. A transrectal MRI is done to find out if the cancer has spread outside the prostate into nearby tissues. This procedure is also called nuclear magnetic resonance imaging (NMRI). Transrectal MRI may be used during a biopsy procedure. This is called transrectal MRI guided biopsy.

A biopsy is done to diagnose prostate cancer and find out the grade of the cancer (Gleason score).

A transrectal biopsy is used to diagnose prostate cancer. A transrectal biopsy is the removal of tissue from the prostate by inserting a thin needle through the rectum and into the prostate. This procedure may be done using transrectal ultrasound or transrectal MRI to help guide where samples of tissue are taken from. A pathologist views the tissue under a microscope to look for cancer cells.

Sometimes a biopsy is done using a sample of tissue that was removed during a transurethral resection of the prostate (TURP) to treat benign prostatic hyperplasia.

If cancer is found, the pathologist will give the cancer a grade. The grade of the cancer describes how abnormal the cancer cells look under a microscope and how quickly the cancer is likely to grow and spread. The grade of the cancer is called the Gleason score.

To give the cancer a grade, the pathologist checks the prostate tissue samples to see how much the tumor tissue is like the normal prostate tissue and to find the two main cell patterns. The primary pattern describes the most common tissue pattern, and the secondary pattern describes the next most common pattern. Each pattern is given a grade from 3 to 5, with grade 3 looking the most like normal prostate tissue and grade 5 looking the most abnormal. The two grades are then added to get a Gleason score.

The Gleason score can range from 6 to 10. The higher the Gleason score, the more likely the cancer will grow and spread quickly. A Gleason score of 6 is a low-grade cancer; a score of 7 is a medium-grade cancer; and a score of 8, 9, or 10 is a high-grade cancer. For example, if the most common tissue pattern is grade 3 and the secondary pattern is grade 4, it means that most of the cancer is grade 3 and less of the cancer is grade 4. The grades are added for a Gleason score of 7, and it is a medium-grade cancer. The Gleason score may be written as 3+4=7, Gleason 7/10, or combined Gleason score of 7.

Certain factors affect prognosis (chance of recovery) and treatment options.

The prognosis and treatment options depend on the following:

• The stage of the cancer (level of PSA, Gleason score, Grade Group, how much of the prostate is affected by the cancer, and whether the cancer has spread to other places in the body).
• The patient’s age.
• Whether the cancer has just been diagnosed or has recurred (come back).

Treatment options also may depend on the following:

• Whether the patient has other health problems.
• The expected side effects of treatment.
• Past treatment for prostate cancer.
• The wishes of the patient.

Most men diagnosed with prostate cancer do not die of it.