Using Hormone Therapy Together with Radiation Therapy
Hormone therapy is injection therapy that turns off the male hormone. It causes the testicles to stop producing testosterone (T). It does the same thing as castration (testicle removal) but is reversible. Most prostate cancer cells need testosterone in order to live and divide into new cancer cells. If you take away the testosterone, the prostate cancer starts to shrivel up as cancer cells die, and the PSA drops down towards 0. Hormone therapy also makes the prostate gland shrink.
It is important to know that just taking hormone therapy by itself can put prostate cancer into remission, but it cannot cure the cancer. There are always some prostate cancer cells that can survive without testosterone, and if you wait long enough (many months – years) these resistant cells will start to divide and form new tumors that don’t need testosterone to grow. What we need to do is add some other treatment to the hormone therapy, like IMRT radiation, to kill “the stragglers”, those cancer cells that can survive testosterone removal.
There are two main uses for hormonal therapy in prostate cancer:
- HT used temporarily along with radiation therapy, to help improve the cure rate.
- HT used indefinitely without other treatment, often for the rest of the patient’s life, to slow down the cancer. It’s especially used this way when a prostate cancer has spread to bones or lymph nodes and is incurable. It will work for several months to several years.
We’ll only be talking about use #1. When a prostate cancer is aggressive, the cure rate from external beam radiation may be improved by adding HT. Aggressive prostate cancers have features like a high Gleason score of 7 and especially 8 – 10, or many of the biopsy cores contain cancer. In one study, the chances of being cancer free at 5 years went from 40% to 74% by adding HT. HT is not used for “low risk” early prostate cancers, unless we need to shrink the size of the prostate gland to be able to safely do radiation.
HT has names like Lupron, Zoladex, Elligard, and Degarelix. They are time-released injections that come in different strengths like 1 month, 3 month, 4 month, and 6 month versions. Typically hormone therapy is prescribed for anywhere between 6 months and 24 months in conjunction with the radiation.
Let’s say your doctors recommends 12 months of hormone therapy. This can be given as a 1-month time released injection given every month for 12 injections total. Or it can be given as a 3-month injection every three months for 4 injections total. Or even as three 1-month injections, followed by one 3-month injection, then a single 6 -month injection. It doesn’t matter. The side effects are the identical for the different strengths. The higher strengths just have to be given less frequently and are therefore more convenient.
HT will cause reversible side effects. These will be covered more in the side effect pages. HT usually causes hot flashes, fatigue or reduced stamina, reduced sex drive, and difficulty getting erections. It can also cause weight gain, muscle reduction, increased hair on your scalp (!), less hair on the body. Your very first injection can take a couple weeks to lower your testosterone so you may not experience any side effects for the first couple weeks. Degarelix starts working much faster.
There is concern that hormone therapy may worsen heart disease, but this is still uncertain. If you have significant heart disease and/or other medical conditions then your doctor may feel that the benefit of adding HT is not worth the risk.
When the HT injections are stopped, the testicles will slowly recover and start to produce testosterone again. It can take 6 months or longer for your testosterone level to climb back up to normal. When this happens, your hot flashes and other symptoms will fade away. During this gradual testosterone recovery period, there can also strangely be some minor breast growth and tenderness.
Once you start on the hormone therapy, we like to wait 2 – 3 months before starting the radiation! This seems very counter-intuitive to most people. But, waiting some time gives the HT a chance to shrink the cancer, drop the PSA, shrink the gland size, and get everything primed for the radiation. The chance of cure is better if we wait. It is important to remember that once you start the hormone therapy you are on cancer treatment.
We will place patients on hormone therapy for different lengths of time depending on how bad the prostate cancer is. Typical durations are:
Low Risk Cancer = None, or 3 months if needed to shrink the prostate gland before radiation.
Gleason score of 6, PSA less than 10
Intermediate Risk Cancer = 6 – 12 months
Gleason score of 7, especially if PSA over 10 or a lot of cancer found on biopsy
High Risk Cancer = 12 – 24 months
Gleason score of 8 – 10, especially if PSA is over 10 or a lot of cancer found on the biopsy. If cancer is in lymph nodes we may use 36 months of HT or longer.
Hormone therapy (HT) is quite complicated! In summary:
- HT lowers the testosterone level in the body.
- HT is given by a series of injections over 6 – 24 months usually.
- HT causes side effects of hot flashes, fatigue, low sex drive.
- The side effects of HT are reversible.
- Most but not all prostate cancer cells need testosterone to survive and thrive.
- HT kills many or most prostate cancer cells, shrinks the tumor, and lowers the PSA.
- We add HT to radiation for aggressive prostate cancers, not for early “low risk” cancers.
- The length of time we use HT, 6 – 24 months, depends on how bad the cancer is.
- We wait 2 – 3 months after starting HT before we start the radiation.
Q) Will I grow breasts if I am on hormone therapy?
A) No. We don’t give female hormones. We give a medication that reduces your male hormones. It’s more like an anti-hormone.
Q) I heard that hormone therapy just slows down the cancer…
A) That is true if hormone therapy is being used on its own. In this case we are using it along with radiation to help increase the chance of curing the cancer.
Q) Is it OK to skip the hormonal therapy?
A) Discuss this with your doctor. In some cases adding hormone therapy will only add a slight benefit, and the added side effects like fatigue and temporary loss of sexual function may not be worth it to you.