What is prostate cancer?
Prostate cancer is the most common non-skin cancer in the United States with around 186,000 new cases in 2008 and it is the second leading cause of cancer death in men behind lung cancer. However, if detected early, prostate cancer can be cured with appropriate treatment. The cause of prostate cancer is unknown but there is a hereditary component.
How is prostate cancer diagnosed?
There are two components to prostate cancer screening. One is a digital rectal examination where the physician places a finger into the rectum to feel the prostate for any suspicious areas of firmness, irregularity, or nodules. The second part of screening is a blood test called the prostate specific antigen or PSA. PSA is protein made in the prostate that typically increases when cancer is present. PSA can be elevated for other reasons such as prostate enlargement or infection, but an elevated PSA often will prompt the urologist to recommend a biopsy.
A prostate biopsy is the only way to definitively diagnose prostate cancer. During a biopsy, a small ultrasound probe is placed into the rectum and the prostate is measured and evaluated for any suspicious areas. Next, a local anesthetic is administered and then 12 needle biopsies are taken and sent to the pathologist to evaluate for cancer. While a biopsy is a very accurate test, it only takes a sampling of the prostate so sometimes may miss an area of cancer so occasional repeat biopsies are necessary.
Once a diagnosis of prostate cancer is made on biopsy, several additional tests may be necessary based on the pathology and the PSA level. Abdominal imaging with a CT scan or MRI is often utilized to look for any enlarged lymph nodes or any evidence that the cancer has spread outside the prostate. A bone scan to look for spread of cancer into the bones is also frequently obtained.
What is the Gleason score?
The Gleason score is how prostate cancer is graded. When the pathologist looks at the biopsy and finds cancer, a score is assigned on a 1 to 5 scale with a 1 being the least aggressive and 5 the most aggressive. The two most common cell patterns are then added together to get the Gleason score. While the score can theoretically range from 2-10, pathologists do not really call prostate tissue cancerous unless the score is at least a 6. Therefore, for all practical purposes, a Gleason 6 is low-risk, Gleason 7 is moderate, and Gleason score 8-10 are aggressive and high risk cancers.
How is prostate cancer treated?
For localized prostate cancer, meaning that the cancer is confined to the prostate based on all available information, there are multiple treatment options. One is referred to as active surveillance means that the PSA level is followed and occasional repeat biopsies are performed and if there is evidence that the cancer is progressing then more definitive treatment is performed.
Another option for localized cancer is radical prostatectomy which can be performed with the aid of the daVinci Surgical System (www.intuitivesurgical.com). During a prostatectomy, the prostate is completely removed and the bladder and urethra are then sutured back together. This allows the pathologist to examine the entire prostate to make sure that all the cancer has been removed and also allows a verification of the Gleason score.
Another option for the treatment of localized prostate cancer is radiation. Radiation can either be administered with small implanted radioactive seeds (brachytherapy) or external beam radiation therapy. Modern radiation therapy utilizes ultrasound and CT imaging to make very detailed treatment plans to treat the prostate with minimal radiation exposure to the surrounding structures.
Another treatment for prostate cancer is cryosurgery during which a special probe is placed into the prostate to freeze the tumor cells, but this treatment is not as well proven for primary treatment and is currently used mostly for recurrence of cancer after radiation therapy.
Due to screening with the PSA blood test, most prostate cancer cases discovered today are localized to the prostate and have not spread to other parts of the body. If prostate cancer does extend outside the prostate, hormonal therapy is often initiated. This includes injections and/or oral medications that help to reduce testosterone levels or block the effects of testosterone in the body. The growth and proliferation of prostate cancer cells are usually testosterone dependent so decreasing or blocking testosterone, the prostate cancer can be controlled, often for many years. Hormonal ablation does cause several side effects such as decreased libido, hot flushes, and osteoporosis which is why hormonal therapy is not typically utilized as primary treatment. In very advanced cases of metastatic prostate cancer, chemotherapy may be used to help control the progression of the disease.