Monitoring the cancer following radiation with PSA
The best way to follow the cancer after treatment is completed is to do regular PSA blood tests. These are done every 3 – 6 months. It is usually not helpful to check it more frequently than every 3 months.
The first time we check the PSA is 3 months after the radiation is completed. It takes that long for the inflammation to settle down and to get a more true PSA reading. If you take a PSA during radiation or right afterwards it may be higher than it originally was! By the 3 month mark, the PSA is typically down to somewhere between 0.5 and 3.0. It will continue dropping for about five years.
If you have been on hormone therapy injections along with the radiation, then the 3 month PSA will be much lower, generally between 0.0 and 0.5.
The PSA Bounce
The PSA can sometimes bounce upward following radiation. Sometimes it may climb up, but the next time it will be down. It can be a little like a roller coaster, up and down, but it should generally trend downwards. So, if the PSA climbs on one or two of your tests do not panic. Just keep getting it checked every 3 months and wait for it to start dropping back down. However, If the PSA climbs up on 3 consecutive measurements and/or it has climbed 2.0 points higher than the minimum value achieved post-radiation, then the cancer may be returning. In that case, your doctor may want to do some more scans or a biopsy, or may offer additional treatment. Sometimes just waiting a little longer might be the best policy, to give the PSA a chance to declare itself — to keep climbing, or to turn around and start dropping. I’ve seen a case where the PSA shot up to 6, I was almost sure the cancer was recurring, but then it spontaneously started dropping back down to zero.
PSA is like a barometer
If the prostate cancer has returned anywhere in the body then the PSA will start to climb. This is very useful. Sometimes the radiation has cured the cancer in the prostate gland, but some cancer cells had already escaped and went into bones or lymph nodes. If prostate cancer starts to grow in the lymph nodes or bones, then the PSA will start to climb.
Think of the PSA as a barometer. Just like a dropping barometric pressure can show signs of an approaching storm long before it shows up, a rising PSA will be the first sign that there is trouble and that the cancer is recurring, long before scans could show cancer in the bones or lymph nodes. This is the reason why we don’t routinely do scans following prostate radiation — the PSA will show the problem first.
Is the PSA accurate?
You have probably heard that PSA is not a very accurate test. That is true when you are using it for screening in men who have never been diagnosed. However, when you use it to monitor the cancer after treatment is completed it is extremely useful. These are two completely different scenarios.
Q) When do I get my first test done after radiation?
A) Three months after the radiation is finished we’ll check the PSA and it is usually dropping by that point, typically (but not always) down to 0.5 – 3.0.
Q) What happens if my PSA is even higher on the first test after radiation?
A) There could still be a lot of inflammation in the prostate, making the PSA high. Be patient and continue checking the PSA every 3 months and give it a chance to drop.
Q) Does the PSA eventually go down to 0 after radiation?
A) Usually not. PSA is produced by health prostate cells and also by prostate cancer cells. So, even if the cancer is completely dead there still can be some PSA being produced by leftover normal prostate cells. Typically (but not always!) the PSA should go down to 0.5 or less by the 5 year mark.
Q) If the PSA goes down to 0 does that mean that the cancer is cured?
A) No. Even if the PSA is at 0.0 the cancer may just be in “remission”, i.e. no signs of the cancer, but it may still come back. If it’s been 3 years or more since you had treatment, and you are not on hormone therapy, then a PSA of 0.0 – 0.3 means you are probably cured.
Q) Will the PSA also go up if the the cancer is in my bones?
A) Yes, If prostate cancer is recurring anywhere in the body the PSA will start to rise. The PSA can actually shoot up very quickly and to very high levels if the cancer is in the bones. I have seen PSA’s as high as 15,000 – 30,000 when it’s been in the bones.
Q) I had my PSA checked during treatment and it was higher!!
A) Radiation can cause inflammation during treamemt and make the PSA spike up. Also, we probably don’t know what your PSA was the day before you started radiation… how long before radiation started was it last checked?