Prostate cancer: when prostate's cells grow out of control

Prostate cancer originates when cells in the prostate gland (found only in men, and whose primary function is to produce part of the fluid that forms semen) begin to grow uncontrollably.

The prostate is an organ located below the bladder and in front of the rectum. Its size typically changes with age: in younger men, it is about the size of a walnut, but it may enlarge as men grow older.

Some prostate cancers can grow and spread quickly, but most grow slowly. Autopsy studies show that many elderly men (and even younger men) who died from other causes also had silent prostate cancer, which did not produce any symptoms or signs. In most cases, neither the men nor their doctors were aware of its presence.

Prostate cancer is the most common cancer among men in the United States, after skin cancer. It is the second leading cause of cancer death in men and occurs more frequently in African American men than in white men. Furthermore, African American men with prostate cancerare more likely to die from the disease than white men with prostate cancer.

There are several types of prostate cancer, but nearly all fall into the main category:

• Adenocarcinoma: this type of prostate cancer develops from glandular cells (the cells that produce the prostate fluid added to semen)

Other, less common types of prostate cancer include:

• Sarcomas
• Small cell carcinomas
• Neuroendocrine tumors (other than small cell carcinomas)
• Transitional cell carcinomas

Although the exact causes of prostate cancer are not fully understood, several factors are known to increase a man's risk of developing the disease.

Widely recognized risk factors for prostate cancer include:

• Age
• Race
• Geography
• Family history
• Genetic changes

Other factors with less clear effects include:

• Diet
• Obesity
• Smoking
• Occupational exposure
• Prostate inflammation
• Sexually transmitted diseases
• Vasectomy

Early-stage prostate cancer typically does not produce symptoms. However, more advanced prostate cancers can cause:

• Difficulty urinating (slow or weak urine flow, or frequent urination, especially at night)
• Blood in the urine
• Trouble achieving an erection (erectile dysfunction)
• Pain in the hips, back (spine), chest (ribs), or other areas
• Weakness or numbness in the legs or feet
• Loss of bladder control

In the early stages (stages I and II), when there is no sign of the cancer spreading beyond the prostate, the 5-year relative survival rate is nearly 100%. Fortunately, approximately 4 out of 5 prostate cancers are detected at this early stage.

When the cancer has spread to nearby areas (stages III and IV), the 5-year relative survival rate remains almost 100%. However, in more advanced stages (stage IV), where the cancer has metastasized to distant lymph nodes, bones, or other organs, the 5-year survival rate drops to approximately 28%.

IMPORTANT: EARLY DIAGNOSIS OF CANCER IS CRITICAL. CANCER DETECTED IN ITS EARLY STAGES—BEFORE IT HAS GROWN TOO LARGE OR SPREAD TO OTHER AREAS OF THE BODY—HAS A MUCH HIGHER CHANCE OF BEING TREATED SUCCESSFULLY. CONVERSELY, IF CANCER HAS SPREAD TO OTHER ORGANS, TREATMENT BECOMES MORE DIFFICULT, AND SURVIVAL RATES ARE GENERALLY MUCH LOWER.

Prostate cancer diagnosis is currently conducted via a prostate biopsy (a procedure to extract small tissue samples from the prostate for microscopic examination).

For this procedure, a thin needle is inserted through the rectum (transrectal biopsy), the urethra, or the area between the anus and the scrotum (perineum), with the transrectal method being the most common. Tissue samples taken during the biopsy are examined for cancerous cells.

A prostate biopsy is typically performed following a PSA test showing elevated prostate-specific antigen levels in the blood or an abnormal prostate or lump detected during a digital rectal exam.

Unfortunately, PSA levels can also rise due to benign prostatic hyperplasia, prostate infarction, prostatitis, or urinary tract infections.

Other factors influencing PSA levels include:

• Rectal exams
• Prostate massage
• Transurethral resection (PSA tests should be done at least six weeks afterward)
• Prostate biopsy (PSA tests should be done at least six weeks afterward)
• Prostate ultrasound
• Cystoscopy

After hormone therapy, PSA levels may not always reflect tumor behavior because anti-androgen medications can lower PSA levels even when residual disease is present.

Potential drawbacks of prostate biopsy include:

• Infections: common in men with undiagnosed prostatitis, although antibiotics before the biopsy usually prevent infection
• Bleeding in the urethra or bladder: this can cause a blood blister (hematoma), difficulty urinating, or frequent urination
• Rectal bleeding: after a transrectal biopsy, minor rectal bleeding may occur for 2 to 3 days
• Allergic reactions: to anesthetic medications used during the biopsy