Prostate Cancer – What it is and Risk Factors

Prostate cancer is the most common form of cancer in men and the second leading cause of male death in North America. Increasing in incidence with age, it is primarily a disease of older men with most of the cases diagnosed in men older than 65 years of age. Each year it is estimated that approximately 189,000 men will receive a prostate cancer diagnosis and 30,000 men will die from its effects. Although prostate cancer is a major health problem for older men the rate of death from it is decreasing because of advances in diagnosis and treatment.

Prostate cancer is curable when diagnosed early. When the cancer is confined to the prostate at diagnosis the five year survival rate is 100%. This percentage drops to 95% if the cancer has spread regionally. Over 75% of all cancer diagnosis are made when the cancer is at one of these stages. In fact, even though they showed no symptoms or complications in life, many men are found to have prostate cancer during autopsy.

The prostate gland consists primarily of glandular epithelial cells. The exact cause of prostate cancer is not known, but it is believed that androgens have a role in its development. Almost all primary prostate cancers are adenocarcinomas, and develop in the peripheral zones of the prostate gland. This location increases the risk of local spread to the prostatic capsule. Despite its proximity to the rectum, metastasis to the bowel is uncommon because a tough sheet of tissue, the Denonvilliers' fascia, acts as an effective physical barrier.

As the tumor enlarges, it may compress the urethra and thereby obstructs urinary flow. The tumor may metastasize and involve the seminal vesicles or bladder by direct extension. Metastasis by lymph and venous channels is also common.

Men with early-state prostate cancer are often asymptomatic, meaning they have no symptoms. Pain from metastasis to the bones is often the first symptom noticed. Urinary symptoms depend on the size and location of the tumor and of the malignancy. The symptoms are often much like those associated with benign prostatic hyperplasia: urgency, frequency, hesitancy, dysuria, and nocturia. There may also be noticeable hematuria or blood in the ejaculate.

Death from prostate cancer usually occurs because of secondary metastasis to the skeletal system and in particular the vertebrae. Compression fractures of the spine are common, resulting in the possible loss of mobility and bowel and bladder function. Tumors may eventually involve bone marrow, resulting in severe anemias and impaired immune function.

In addition to age, race is a significant risk factor for prostate cancer. African American males have the highest incidence of prostate cancer in the United States and the world, with rates more than twice as high as white males. They are also more likely to be diagnosed later and to die of prostate cancer, with a mortality rate more than double that of other racial and ethnic groups. Asians and Native Americans have the lowest incidence of prostate cancer.

Other risk factors for prostate cancer include:

• Genetic and hereditary factors, with risk increased in men who have a family history of the disease.
• Having a vasectomy which is believed to increase the levels of circulating free testosterone.
• Dietary factors including a diet high in fat and red meats, low in vitamin A, vitamin D, lycopene, and selenium
• Low exposure to sunlight.