How Does a Doctor Diagnose Prostate Cancer?

The prostate gland or prostate is a part of the male reproductive system.

The prostate gland or prostate is a part of the male reproductive system. It is a small (almost walnut-sized) gland located just below the bladder and in front of the rectum (the last part of the large bowel), surrounding the urethra (the tube carrying urine out of the bladder). The prostate has two main functions: producing and storing fluid that helps make semen and regulating bladder control.

Prostate cancer is an uncontrolled growth of cells in the prostate gland. It is the second most common cancer in males in the United States (the first being skin cancer). Around 13 out of 100 men get prostate cancer during their lifetime in America.

The most definite way to diagnose prostate cancer is by taking a tissue sample from the gland and examining it under a microscope. This is called a prostate biopsy. The doctors, however, do not directly conduct a biopsy without doing the simpler and less invasive clinical assessments and diagnostic tests. The diagnosis of prostate cancer is based on the following:

• Detailed medical history. This includes asking the person about their symptoms, any underlying health conditions (such as diabetes, high blood pressure), and whether they consume alcohol or tobacco in any form. They may also be asked whether they have a close family member (father, uncle, or brother) diagnosed with prostate cancer at an early age (younger than 65 years). Other questions, such as any change in sex drive or loss of body weight, may also be asked.
• Thorough physical examination. The doctor may assess the person’s general health status by looking at any signs of diseases through their physical examination. They may also perform a digital rectal examination or DRE. During a DRE, the doctor will insert a gloved, lubricated finger into the person’s rectum and try to feel any lumps, irregularities, or hard areas on the prostate that might suggest cancer. This examination will also give clues whether cancer has involved one or both sides of the prostate and whether it has spread to nearby structures.
• Blood tests. Certain blood tests may be done to examine blood counts, inflammatory markers (substances raised in the blood in response to infection or inflammation), or any other relevant parameters. The blood test may also include measuring the levels of a type of protein called prostate-specific antigen or PSA. This protein is made by both normal and cancerous cells in the prostate. PSA levels cannot accurately diagnose whether a person has or doesn’t have prostate cancer. Thus, it is generally done for screening high-risk groups or as a preliminary test. Most people without prostate cancer have PSA blood levels lesser than 4 ng/mL (nanograms per milliliter). There is almost a 50 percent chance that a person has prostate cancer if their blood PSA levels are above 10 ng/mL. It is, however, seen that men with prostate cancer may have PSA lesser than 4 ng/mL. Also, higher PSA levels may be seen in noncancerous conditions, such as benign prostatic hyperplasia (BPH).
• Magnetic resonance imaging (MRI) scan. Suspicious PSA and DRE may prompt the doctor to conduct an MRI of the prostate. An MRI will give a better idea about the mass (if any) felt on DRE.
• Prostate biopsy. This is the only way for knowing with certainty whether a person has prostate cancer or not. It involves taking a tissue sample from the gland and examining it under a microscope. During the procedure, the doctor inserts a thin needle into the prostate under image guidance (using an MRI and/or a transrectal ultrasound or TRUS) to collect a tissue sample. The tissue is then examined in a lab to identify cancer cells. The biopsy needle may be inserted through the rectum (a transrectal biopsy) or the skin between the scrotum and anus (a transperineal biopsy).

Other tests, such as ultrasound, computed tomography (CT) scan, and positron emission tomography (PET) scan, may also be done to look for the presence of cancer and whether it has spread to other sites in the body.