Prostate cancer is the second most common cancer diagnosed in American men.
In 2009, over 206,000 men in the United States were diagnosed with the disease.
The cancer begins in a man's prostate, a gland that creates seminal fluid and transports sperm.
Some types of the disease grow slowly and do not require treatment, but other more aggressive types spread quickly.
The medical community does not know exactly what causes prostate cancer, but the disease begins when cells in the gland become abnormal.
The abnormal cells contain mutated DNA that causes them to divide and grow faster than normal cells.
These abnormal cells outlive normal cells, forming a tumor as they accumulate.
Doctors have identified some risk factors for developing the cancer.
Older men are more likely to develop the disease, and it is most common in men over the age of 65.
African American men are also more likely to have the cancer, and it is typically more aggressive in this demographic than among men of other races.
The risk of developing the disease is also greater for men who have a family history of prostate cancer and those who are obese.
In its early stages, the cancer often does not cause signs or symptoms.
More advanced stages of the cancer may cause blood in the urine, bone pain, trouble urinating, discomfort in the pelvic area, decreased streaming of urine, swelling in the legs or blood in the semen.
Some medical organizations recommend regular prostate screenings for men in their 40s.
These screening tests may include digital rectal exams or prostate-specific antigen tests.
These tests may help identify the cancer in its earliest stages.
If the screening tests lead to abnormal results, a doctor may recommend an ultrasound or prostate biopsy to confirm the presence of cancer.
Doctors grade the cancer using tests like ultrasounds, CT, MRI or bone scans.
During stage I, the cancer is confined to a very small part of the prostate gland, and the cancer cells are not labeled aggressive.
During stage II, the cancer has grown to involve both sides of the gland, or the cancer cells are considered aggressive.
Stage III is diagnosed when the cancer has spread beyond the gland to nearby tissues.
During stage IV, the cancer has invaded other parts of the body, like the bladder, lungs or bones.
The treatment plan prescribed for this type of cancer varies depending on the patient's overall health, the cancer's stage and other factors.
Treatment may include radiation therapy, hormone therapy, cryotherapy, surgery or chemotherapy.