Table of Contents

Chapter 6: Using Hormone Therapy

a. Why Hormone Therapies Work

As we mentioned earlier, the goal of all hormone therapies is to somehow interfere with the way that testosterone acts on the prostate cancer cells and allows them to grow. Although this is true in the broad sense of prostate cancer, in reality, not all cells are sensitive to increases or decreases in testosterone levels, making hormone therapy a somewhat imperfect weapon in the fight against prostate cancer. It is therefore important to understand that hormone therapy is a treatment for prostate cancer but does not cure the disease.

Think about the last time you had an infection that required antibiotics. The doctor gave you a prescription for a few days’ worth of antibiotics, and you took all of the pills as prescribed. By the end of the course of therapy, the pills had killed off the infection and you were all healed, right? Well, not exactly.

Each type of antibiotic is very effective against a particular group of bacteria. But it’s not uncommon to have a few different groups of bacteria in your system at any one given time. The antibiotic that you took killed off the majority of the bacteria, and likely left a small amount that it was unable to affect. And that’s ok, because your body at that point was strong enough to fight off the remaining bits of infection on its own, without any help from the pills.

When it comes to prostate cancer, the process is the same, but with two very important differences. First, although the body is usually strong enough to fight off a low-level infection, it’s rarely strong enough to fight off cancer on its own. Because the majority of the cells in prostate cancer tumors respond to the removal of testosterone, hormone therapies can keep the cancer under control. But the cells that grow independent of testosterone remain unaffected and grow unchecked. Which means that after some period of time—maybe a few months, more likely a few years, maybe even a decade or more—those hormone-independent prostate cancer cells will become strong enough that hormone therapies will have less and less of an effect on the growth of the tumor.

Second, antibiotics actually kill the bacteria; hormone therapies can kill cancer cells, or in many instances, merely slow down the growth of prostate cancer cells. Which is why the therapies are continued even after the hormone-independent cells have grown enough to start causing trouble. It’s true that the therapies can’t affect the growth of the independent cells, but the hormone-sensitive ones are still there, and still need to be kept under control.

How do we know when the balance has begun to shift in favor of the hormone-independent cells? Your PSA levels will let us know. Just as a rising PSA following prostatectomy or radiation therapy is an early warning sign that the cancer has started to grow again, a rising PSA despite hormone therapy is an early warning sign that the tumor is becoming less and less sensitive to the changes in testosterone. A rising PSA doesn’t mean that the hormone therapy isn’t working, it simply means that it’s not working enough, and that it might be time to start investigating other options.

Hormone therapy is not a perfect strategy in the fight against prostate cancer, and, on average, is effective for only a few years. But it remains an important step in the process of managing advancing disease, and will likely be a part of every man’s therapeutic regimen at some point during his fight against recurrent or advanced prostate cancer.