Hormone therapy for prostate cancer is a treatment that lowers levels of male sex hormones (androgens) or blocks their ability to fuel cancer growth. Prostate cancer cells rely on testosterone to survive and multiply, so cutting off that supply slows or shrinks the disease. It is one of the most common treatments for advanced prostate cancer and is also used alongside radiation or surgery in earlier stages.
How Hormone Therapy Works
Prostate cells, both healthy and cancerous, have proteins called androgen receptors on their surface. When testosterone binds to these receptors, it switches on genes that tell the cells to grow. Hormone therapy either starves cancer cells of testosterone or physically blocks testosterone from attaching to those receptors. Either way, the growth signal gets shut down.
The testicles produce roughly 90 to 95 percent of the body’s testosterone. The remaining small amount comes from the adrenal glands and, in some cases, from the tumor itself. Different types of hormone therapy target different sources, and newer treatments can block production from all three at once.
Early in the disease, prostate cancer cells are highly dependent on testosterone. This stage is called castration-sensitive prostate cancer, and hormone therapy typically works well here. Over time, however, some cancer cells adapt. They find ways to keep their androgen receptors active even when testosterone in the bloodstream drops below 20 nanograms per deciliter. When this happens, the cancer is reclassified as castration-resistant, a stage that requires additional or different treatments.
Types of Hormone Therapy
Drugs That Lower Testosterone Production
The most widely used approach involves injectable drugs that act on the brain’s signaling system to shut down testosterone production in the testicles. These come in two forms. The first type initially causes a brief surge in testosterone before overwhelming the system and forcing it to shut down, typically reaching very low testosterone levels within two to four weeks. The second type skips the surge entirely and drops testosterone rapidly, which can matter for men whose cancer could worsen from even a short spike. Both are given as injections, ranging from monthly to every six months depending on the formulation.
A separate class of drugs blocks an enzyme involved in making androgens not just in the testicles but also in the adrenal glands and within the tumor itself. This is particularly useful in castration-resistant disease, where the cancer has learned to use those alternative testosterone sources.
Drugs That Block Testosterone’s Action
Rather than lowering testosterone levels, these medications compete with testosterone for the androgen receptor. They physically prevent testosterone from docking onto the receptor, so even if some hormone is circulating, it can’t activate cancer growth. Newer versions of these blockers are significantly more potent than older ones and can also stop the receptor from entering the cell nucleus, where it would normally switch on growth genes.
Surgical Removal of the Testicles
Because the testicles are the primary testosterone factory, removing them (a procedure called orchiectomy) achieves the same hormonal result as drug therapy. Both approaches suppress testosterone effectively, with over 95 percent of patients reaching castration-level testosterone regardless of method. Side effect profiles are similar as well, with comparable rates of bone fractures, blood sugar changes, and heart-related events in large studies. The key difference is cost: surgery is a one-time expense, while drug therapy requires ongoing injections that roughly double the long-term price. Most men today choose drug therapy because it’s reversible and doesn’t involve permanent surgery, but orchiectomy remains a reasonable option, especially where ongoing access to injections is difficult.
When Hormone Therapy Is Used
Hormone therapy plays different roles depending on how advanced the cancer is. For cancer that has spread to other parts of the body (metastatic disease), it is the backbone of treatment and is typically started right away. For locally advanced cancer that hasn’t spread beyond nearby tissues, it’s often combined with radiation therapy to improve cure rates. It can also be used when PSA levels rise after surgery or radiation (called biochemical recurrence), signaling that some cancer cells remain.
Current treatment guidelines emphasize that decisions about hormone therapy should account for whether metastases appeared at the time of initial diagnosis or developed later, how widespread the disease is, and what other treatments the patient has already received. For metastatic castration-sensitive disease, intensified combination approaches are now standard. This means adding a second hormonal agent or chemotherapy on top of basic testosterone suppression, rather than using testosterone suppression alone.
Continuous vs. Intermittent Treatment
Some men receive hormone therapy continuously, while others cycle on and off in an intermittent schedule. The idea behind intermittent therapy is to give the body a break from side effects during the off periods. A large trial published in the New England Journal of Medicine followed men with metastatic hormone-sensitive prostate cancer for nearly 10 years and found that intermittent therapy provided small improvements in erectile function and mental health, particularly in the first few months off treatment. However, median survival was 5.1 years with intermittent therapy compared to 5.8 years with continuous treatment. The study couldn’t rule out up to a 20 percent greater risk of death with intermittent therapy.
For men with lower-volume disease or those using hormone therapy for a rising PSA without visible metastases, intermittent therapy may still be a reasonable option. For men with extensive metastatic disease, continuous therapy is generally preferred.
Side Effects and Long-Term Risks
Because testosterone affects far more than the prostate, lowering it produces wide-ranging side effects. Hot flashes are among the most common and most immediately noticeable. Loss of sex drive and erectile difficulties happen in the majority of men. Fatigue, reduced muscle mass, and weight gain (particularly around the midsection) develop over the first several months. Breast tissue can also enlarge and become tender.
The longer hormone therapy continues, the more serious the health risks become. A nationwide cohort study in Korea found that men on hormone therapy developed osteoporosis at a rate of 8.8 percent compared to 7.1 percent in men not on therapy, and fractures occurred in 8.1 percent versus 5.0 percent. These risks climbed steadily with longer treatment duration. Fractures are particularly concerning because they’re linked to increased mortality in prostate cancer patients. Bone density monitoring and protective measures are typically part of long-term care for men on this treatment.
Metabolic changes are another major concern. Hormone therapy increases the risk of diabetes and cardiovascular disease. Men often experience rising cholesterol, insulin resistance, and shifts in body composition that collectively raise heart risk. These effects don’t reverse immediately when treatment stops, making cardiovascular health an important area to monitor throughout and after treatment.
When the Cancer Stops Responding
Most prostate cancers initially respond well to hormone therapy, but the duration of that response varies widely between patients. Eventually, many cancers develop resistance. The formal definition of castration-resistant prostate cancer requires two things: testosterone in the bloodstream staying below 50 nanograms per deciliter (confirming the therapy is working as intended), and evidence that the cancer is progressing anyway. Progression can show up as a rising PSA (specifically, a 25 percent increase on two consecutive tests at least a week apart, with the PSA above 2.0), new spots on bone scans, or growing tumors on imaging.
At this stage, basic testosterone suppression continues because stopping it could still allow the cancer to accelerate. But additional treatments are layered on top. These include more potent androgen receptor blockers, drugs that shut down androgen production from all sources, chemotherapy, immunotherapy, radiopharmaceuticals that target bone metastases, and in some cases targeted therapies based on the tumor’s genetic profile. The sequencing of these treatments depends on what was used earlier, the location and extent of metastases, symptoms, and the patient’s overall health and preferences.