Ask The Doctors: Treatment Options
Industry News Leading experts answer your questions about prostate cancer, treatment options and clinical outcomes.
Mediaplanet: What are the different stages of prostate cancer?
Dr. Laurence Klotz: Small areas of low-grade prostate cancer develop normally with age in most men; this is known as ‘latent’ or ‘clinically insignificant’ cancer. In some men, the cancer progresses to become larger, or higher grade; this is ‘localized prostate cancer’ and is diagnosed in about 10 percent of men. The next stage is progression or spread of the disease outside the prostate to lymph nodes and bone; this is ‘metastatic prostate cancer’. When the disease progresses despite the use of hormonal therapy, it is termed ‘castrate resistant prostate cancer’. This stage can be fatal, and affects 3 percent of men.
Dr. Rob Bristow: In order to help clinicians and patients choose treatment options, localized prostate cancer (without spread of disease to lymph nodes or bone) is classified as low-risk, intermediate risk or high risk/locally advanced based on the relative level of pathologic Gleason score, Prostate Specific Antigen (PSA) test and local involvement (i.e. T-category) of the cancer (e.g. called T1 if found only on needle biopsy, T2 if the lesion can be felt during rectal exam, and T3/T4 are lesions growing outside the prostate gland).
MP: What treatment options are available for metastatic prostate cancer?
LK: Prostate cancer that has spread to other organs (usually bone) is treated with hormonal therapy, the purpose of which is to lower the level of testosterone to close to zero. This results in death of cancer cells. This can be achieved either by surgical removal of the testicles (castration), female hormones or LHRH agonists or antagonists. The LHRH antagonists act by stopping the secretion of LH, the pituitary hormone that controls testosterone secretion from the testicles. FSH, which controls spermatogenesis, is also lowered.
RB: In high-risk/locally advanced cancer, there is concern about microscopic disease outside the prostate and throughout the body (the latter needing systemic therapy in the form of hormone therapy using LHRH agonists). As such, these more aggressive cancers are treated with surgery, followed by local radiotherapy or external beam radiotherapy plus six months to three years of LHRH agonists.
MP: What is the benefit of using these treatment options?
LK: The LHRH antagonists, unlike the agonists, do not induce an initial ‘surge’ of LH and testosterone, which may be harmful by stimulating prostate cancer cell growth. In addition, the levels of FSH are lowered more by the antagonists. The antagonists appear to provide a longer duration of response and a decreased risk of cardiovascular problems — like heart attack and stroke — compared to the agonists. A disadvantage of the antagonists is that they require monthly injection, compared to every three to four months with the agonists.
RB: The combined use of hormone therapy (LHRH agonists: six to 36 months duration) with radiotherapy has revolutionized prostate cancer treatment for patients with high-risk/locally advanced prostate cancer with improvements in overall survival by 20 to 30 percent. The use of hormone therapy with surgery in these patients is also actively being explored. Due to the potential side-effects of LHRH agonists in some patients, all patients should discuss with their specialists ways to maintain bone and muscle strength, watch for changes in blood sugar and ways to combat hot flashes and fatigue.