Prostate cancer

ALSO KNOWN AS: Adenocarcinoma of the prostate

RELATED CONDITIONS: Benign prostatic hyperplasia (BPH), prostatitis

DEFINITION: Prostate cancer is the growth of cancer cells in the prostate. A majority of prostate cancers start in the prostate gland. This type of cancer is referred to as an adenocarcinoma. There are other types of cancer cells that start in the prostate, but adenocarcinoma is the most common.

The prostate is a male reproductive gland located in front of the rectum and below the bladder that produces semen, the fluid that nourishes and transports sperm. The gland surrounds the urethra, the tube that carries urine outside the body. It is normally about the size and shape of a walnut.

Risk factors: The risk of getting prostate cancer increases with age. About 60 percent of all diagnosed prostate cancer is found in men over sixty-five. Prostate cancer is rare before the age of forty. Prostate cancer is the most common form of cancer among men, after skin cancer. Men with a family history of prostate cancer in an immediate relative, such as a father or brother, are two to three times more likely to develop the disease. The disease is also more common among Black American men, with more men in this racial group dying from the disease than in any other ethnic group. It is less common in men who are Hispanic, Asian, American Indian, or from the Pacific Islands.

Etiology and the disease process: Prostate cancer is typically a slow-growing, silent disease that strikes older men. More men with prostate cancer are never diagnosed and never have symptoms than there are men diagnosed with the disease. However, some men develop an aggressive illness that can be life-threatening. There is not a clear understanding as to why some men develop an aggressive form of the disease while others may never know they have it.

Incidence: Prostate cancer is the second most common form of cancer among men in the United States (the most common is skin cancer) and the third leading cause of death, behind lung cancer and colorectal cancer. The American Cancer Society estimates about 300,000 new cases of prostate cancer are diagnosed in the United States each year, and approximately 35,000 men die from it.

Symptoms: Often, there are no symptoms until the disease has spread beyond the prostate, a condition called metastasis. Common symptoms may include frequent urination, a sudden urge to urinate, a weak urine stream, dribbling after urinating, straining to urinate, the inability to prevent urine leakage, or the sensation that the bladder is not empty even after urinating. Blood in the urine or semen, painful ejaculation, and pain in the lower back, hips, or thighs are also common complaints. The symptoms of prostate cancer are similar to those of the noncancerous conditions of benign prostatic hyperplasia (BPH), prostatitis, or a urinary tract infection. If these symptoms occur, it is important to be checked by a doctor to determine the cause.

Screening and diagnosis: There are two tests commonly used to screen for prostate cancer: the prostate-specific antigen (PSA) blood test and the digital rectal exam (DRE). PSA is a protein produced by normal and cancerous prostate cells that is released into the blood. This test measures the levels of PSA in the blood. High levels of PSA may be indicative of prostate cancer or noncancerous conditions.

For a digital rectal exam (DRE), the physician inserts a gloved, lubricated finger into the rectum to check the prostate for any unusual characteristics, such as an increase in size, nodules, or lumps. The benefit of the DRE as a screening tool for prostate cancer is that it can reach a part of the prostate gland where most cancers generally begin.

Men at high risk for the disease should begin testing with a DRE and a PSA test at age forty-five. The recommended guidelines suggest testing for all other men starting at age fifty.

Additional testing is recommended if the PSA is high or there are suspicious findings during the DRE. These tests may include a transrectal ultrasound or a biopsy. With a transrectal ultrasound, a small probe is inserted into the rectum to take ultrasound images of the prostate. A biopsy is taken if a suspicious area is found during the exam. A biopsy is usually done with local anesthesia in a doctor’s office. A small needle is inserted into the prostate to remove tissue samples. These samples are then examined under a microscope by a pathologist, a doctor who specializes in identifying diseases by examining tissues and cells to determine if cancer cells are present and, if they are, how aggressive the disease may be.

When prostate cancer is diagnosed, it is given a Gleason score. The Gleason grade is between two and ten, reflecting how closely the cancer cells resemble normal prostate tissue. Generally, a low Gleason score suggests less aggressive tumors, and a higher Gleason score suggests more aggressive tumors.

The stage of the cancer refers to the extent of the disease based on tumor location, size, number of tumors, and whether the cancer has spread outside the prostate gland to surrounding organs. Stages I and II refer to early-stage disease that is confined to the prostate. Stage III refers to a locally advanced disease that has spread outside the prostate gland. Stage IV refers to cancer that has metastasized and possibly spread to the lymph nodes and other organs in the body.

Treatment and therapy: There are several treatment options, depending on age, overall health of the patient, and stage and grade of cancer. For men with local or locally advanced prostate cancer, treatment options generally include radical prostatectomy, radiation therapy, hormone therapy, cryotherapy, and watchful waiting. Radical prostatectomy is the surgical removal of the prostate gland and surrounding tissues. Radiation therapy is the administration of radiation energy to the prostate to destroy the cancer cells. Hormone therapy involves treatment to lower testosterone levels in the body, thereby reducing prostate cancer cell growth. Cryotherapy involves inserting a probe into the prostate to destroy cells by freezing the prostate gland. Watchful waiting, sometimes called active surveillance, is monitoring the progression of the disease with regular examinations and testing. This option is usually recommended for men with other medical conditions or for those who would not tolerate surgery well.

For men with metastatic prostate cancer or men with returning cancer after surgery or radiation treatment, hormone therapy and chemotherapy are treatment options. Hormone therapy reduces prostate cancer cell growth, and chemotherapy destroys the cancer cells circulating throughout the body. Another option may be enrollment in ongoing clinical trials. Patients should discuss these options with their doctors and families to decide the best option.

Prognosis, prevention, and outcomes: Approximately 80 to 85 percent of prostate cancer is discovered in the early stages of the disease. When found at the local stage, in which there is no sign that cancer has spread beyond the prostate, the five-year survival rate is almost 100 percent, and the fifteen-year survival rate is around 91 percent. When the cancer has spread to surrounding tissues or organs, the survival and cure rates vary, depending on the type and extent of the disease. When diagnosed at the distant stage, in which the cancer has metastasized to distant lymph nodes, bones, or other organs, the five-year survival rate drops to 34 percent.

As with other types of cancer, there is no definitive way to prevent prostate cancer. Good overall health, a diet low in fat and high in fruits, vegetables, and whole fibers, and plenty of exercise can strengthen the immune system and potentially slow the onset of cancer.

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