Hormone Therapy for Prostate Cancer
The topic of hormone therapy for prostate cancer can also be a confusing topic for patients. Hormone therapy is not used to cure prostate cancer as surgery, radiation or cryotherapy attempt to do. Rather, hormone therapy is primarily used today as an effective way to control metastatic prostate cancer (cancer that has spread throughout the body, most typically to bones and lymph nodes). It is also used as an adjunctive treatment used during radiation therapy due to some evidence that it acts as a radiosensitizer and thus makes cells more susceptible to radiation therapy. Therefore, hormone therapy is not typically discussed in detail when being initially counselled regarding a new diagnosis of prostate cancer unless as a part of initial radiotherapy treatment. As such, hormone therapy is reserved for patients who either present with known metastatic disease, or for those patients who have undergone local therapy only to find later that this has failed due to metastatic disease.
In some ways, hormone therapy is a misnomer. Unlike hormone replacement therapy in men or women, where testosterone or estrogen is supplemented in a patient to reverse low levels of these hormones in the body, hormone therapy for prostate cancer is actually the act of causing the body either to not make any testosterone, or by giving a drug that will block the action of testosterone in the body. This is effective because, just as is seen with some breast cancers that rely on estrogen, prostate cancer cells need testosterone to thrive. Without the actions of testosterone, nearly all of the prostate cancer cells in a patient will die. However, not all of them will be affected by hormone therapy due to the fact that of millions of cells there will always be a small population that can live and grow without testosterone. Eventually, this small subset will eventually make up the entire population of cells. It is at this point that hormone therapy will no longer be effective and other treatments, such as new anti-androgen drugs or receptor blockers, chemotherapy and immunotherapy will be needed. It is the Urologist that generally oversees the administration of hormone therapy. Once it begins to fail, the patient is usually referred to an Oncologist for other therapies.
Therefore, the question when one is started on hormone therapy is not if it will be effective, as it nearly always is in terms of killing nearly all the cells and thus causing the PSA to drop to nearly undetectable levels. The question is how long the hormone therapy will be effective. In some, this can be many years – even 8-10 years. In others, this period is far shorter. What tends to be the determinant of this is how aggressive the initial cancer is in terms of Gleason score, how high the PSA was when the hormone therapy was started, and the extent of metastatic disease. Really the only way to get a sense of how long the therapy will be effective is to gauge the PSA response and then see if the PSA stays very low at first or not.
There are different ways to treat a patient with hormone therapy, which was alluded to above. The most common class of drugs are called 5-alpha reductase inhibitors. These drugs trick the brain into thinking there is an abundance of testosterone in the blood. The brain then sends chemical messages to the testicles to stop making any testosterone, and it is in this way that an extremely low level of testosterone is reached. The most common drugs in this class are named Lupron and Eligard, but there are others. These drugs are given as injections in the office, and most commonly last for four months at a time although this also varies. The main side effect of these drugs is hot flashes much as a woman would experience during menopause. These can be considerable at first but often diminish over time. Lack of testosterone will also lead to low libido or interest in sex, can decrease energy and lead to poor erections primarily via causing low libido. At times, testosterone receptor blocker drugs are given as a second drug either to get more effect from the first, or to put a patient on hormone therapy quickly before a shot is given. These receptor blockers are once a day pills, the most common of which today being Casodex (bicalutamide). Recently several other non-generic drugs have been introduced from this class that may hold more promise than Casodex.
Even with shots, there are different techniques and strategies employed. One option is to give hormone therapy continuously, although we often prefer to give hormone therapy intermittently. The latter approach may greatly lessen the incidence of osteoporosis, cognitive function effects, and other long term effects. The way this is done is to give hormone therapy, have the psa drop to a very low number, keep it there for a year and then stop the hormone therapy. The psa will then be allowed to rise to between 3 and 5 at which time the cycle starts again. There is also theoretical evidence that giving hormone therapy in this manner will also potentially lengthen the overall period of effectiveness. Intermittent therapy also allows libido to return when off the drug. However, not everyone is a candidate for intermittent hormone therapy. Patients with symptomatic or bulky metastasis would be an example. Also, today we most commonly will not start hormone therapy immediately upon suspecting metastatic disease. Rather, we follow the evidence that suggests that there is no benefit to starting hormone therapy early rather than waiting for the psa to rise to approximately 20 initially before starting hormone therapy. It can take years to reach this point, thus also lessening the overall time a patient is on hormone therapy.
No two cases are identical, and if diagnosed with metastatic prostate cancer the treatment approach with hormone therapy can vary based on several factors not least of which being the findings of a radiologic workup consisting of a bone scan and CT scan. There are options, and we will help you find the option that fits your case and your lifestyle best. A main concept to keep in mind is that metastatic prostate cancer is not an automatic death sentence. It is a chronic disease that can be very effectively managed and controlled for very long periods of time.