Definition of Cure:
Most patients look to the word ‘cure’ as a promise. There are no guarantees in life, but there are ways to measure success and outcomes.
Learn various approaches on those measurement tools within the medical community, so that you can compare “apples to apples” in the decision making process.
If you are newly diagnosed with prostate cancer and want to speak with a member of the Radiotherapy Clinics of Georgia team, visit our patient contact center.
Question 105:
How do you determine if a man is cured of prostate cancer? (See Figure 20.)
Answer:
Cure is determined by the PSA test after any treatment. However, instead of one definition of cure for all treatment methods so that you can compare methods, there are three different PSA definitions of disease freedom that doctors use:
- PSA cutpoint 0.2 ng/ml. This definition is the only one that defines cure. Cure refers to the fact that a man’s PSA after treatment must fall to 0.2 ng/ml or lower and remain at this level forever. Recurrence, or regrowth, of prostate cancer after treatment is defined by a rise above PSA 0.2 ng/ml, which is For example, a PSA rise to 0.21ng/ml or confirmed by a second rise above 0.2 ng/ml.1 more that is confirmed by a second PSA of 0.21 ng/ml or more. ProstRcision and radical prostatectomy are calculated with PSA cutpoint 0.2 ng/ml.
- The ASTRO definition. This definition does not define cure. In this definition, the PSA does not have to fall to 0.2 ng/ml. Recurrence is defined by three consecutive (the key word is consecutive) PSA rises above the lowest PSA level. For example, consider a man’s PSA that falls to 0.2 ng/ml after treatment, then rises to 0.7 ng/ml, then 1.8 ng/ml, is held at 1.8 ng/ml, then goes to 2.9 ng/ml and finally reaches 4.4 ng/ml. Since there were not three consecutive PSA rises, this patient would still be considered free of prostate cancer according to the ASTRO definition, even though his PSA went from 0.2 to 4.4 ng/ml. If his PSA were to go to 7.3 ng/ml, he would experience three consecutive rises and would be considered as having recurrent prostate cancer.
- Nadir+2 (or Phoenix) definition. Like the ASTRO definition, the nadir+2 definition does not define cure. Also, like the ASTRO definition, PSA does not have to fall to PSA 0.2 ng/ml. Recurrence of prostate cancer is defined by a rise of 2.0 ng/ml above the lowest level achieved. If a man’s PSA fell to 0.2 ng/ml, then to 0.7 ng/ml, followed by 1.1 ng/ml, then 1.4 ng/ml, then 1.6 ng/ml, and finally 1.9 ng/ml, this man would still be classified as prostate cancer free even though his PSA is rising. To be classified as having recurrent cancer, the PSA would have to rise to 2.2 ng/ml.
As you can see, there is a marked difference in the PSA cutpoint 0.2 ng/ml definition of cure compared to the ASTRO and nadir+2 definition, neither of which defines cure from prostate cancer. Instead, the latter two definitions only define “control” or “remission” of prostate cancer.48,49 To document this, a small study of men who received beam radiation for prostate cancer followed years later by prostatectomy revealed that 50% of the men classified as in remission by the nadir+2 definition still had cancer in their prostate when the specimen was examined under the microscope.50 All of this is important for you to know because, with two exceptions, all peer-reviewed medical reports on treatment methods for prostate cancer other than ProstRcision and radical prostatectomy have outcomes calculated using either the ASTRO or nadir+2 definition. Doctors using the eight other treatment methods listed in Table 1 refuse to calculate cure rates with PSA cutpoint 0.2 ng/ml because they consider this definition too strict.49 See Figure 20.
Question 106:
This does not make sense. Why don’t all doctors use PSA cutpoint 0.2 ng /ml, which is the only definition that shows cure from prostate cancer? (See Table 6.)
Answer:
The reason doctors calculate with the ASTRO or the nadir+2 definition is because these two definitions produce a lot better outcomes than calculations with PSA 0.2 ng/ml. This is extremely important for a man with prostate cancer to know, because the purpose of treatment is to be cured and not just to have the cancer controlled or put in remission. If all doctors calculated cure rates with PSA 0.2 ng/ml after all treatment methods for prostate cancer, you would find that many treatment methods have very poor cure rates (see Table 1).
Question 107:
Is there a difference in outcomes if you calculate cure rates with PSA 0.2 ng /ml in a group of men with prostate cancer and then calculate outcomes in the same group of men but use the ASTRO or nadir+2 definition?
Answer:
There is a huge difference. One medical report made this comparison in men treated with external beam radiation with the conformal technique, where 6,500–7,000 cGy was given to the prostate. The study consisted of 4,839 men treated at several major medical centers including M.D. Anderson Hospital, Fox Chase, Cleveland Clinic, Mayo Clinic, University of Michigan and Memorial Sloan Kettering Hospital.8 Cure rates were calculated with PSA 0.2 ng/ml in these men, and outcomes were calculated using the ASTRO definition. Table 6 shows the difference in outcomes if the definition is changed. As you can see, there is a big difference in results, and this depends solely on which definition a doctor decides to use. In this report, the doctors claim that 49% of men were free of cancer using the ASTRO definition, when in fact only 3% of these men were actually cured. Had the nadir+2 definition been used, it would have given the same misleading results as the ASTRO definition. Calculations of outcomes after treatment of prostate cancer using either the ASTRO or nadir+2 definition are inflated.50 Further, they do not measure cure of prostate cancer. Consequently, 10-year outcomes between treatment methods cannot be compared unless the SAME PSA definition is used.
Question 108:
Since the ASTRO and nadir+2 definition do not measure cure and produce
inflated results, what can a man do to get accurate cure rates from any doctor using any treatment method?
Answer:
Be precise and ask the doctor for the number of men he has treated; ask how many of those same men had PSA 0.2 ng/ml 10 years after treatment (see the four questions for doctors in Question 2). To give men with prostate cancer an apples-to-apples comparison, we estimated the cure rates for the 10 treatment methods listed in Table 1 as if calculations were made with PSA cutpoint 0.2 ng/ml.
Question 109:
Is it fair to estimate cure rates using PSA 0.2 ng / ml for the doctors who use other treatment methods?
Answer:
Doctors who write medical research papers or talk to men about the outcomes of treatment methods for prostate cancer choose whichever definition they want to use for their calculations. Doctors who calculate with the ASTRO or nadir+2 definition chose to calculate with these methods instead of using the standard definition of cure, which is defined as PSA cutpoint 0.2 ng/ml. We suspect that when doctors calculate using PSA 0.2 ng/ml, they find the results to be very low and decide to “improve” them by calculating with the ASTRO or nadir+2 definition, as in Question 104. At Radiotherapy Clinics of Georgia, we could “improve” our outcomes by calculating with the ASTRO or nadir+2 definition rather than using PSA cutpoint 0.2 ng/ml. In fact, we could change approximately one-third of the men in our database who have recurrent prostate cancer to being “free of cancer” which would significantly (but artificially) inflate our results. However, we calculate with PSA 0.2 ng/ml because we want to give men accurate cure rates, which is the same reason urologists calculate with PSA 0.2 ng/ml after radical prostatectomy. The only purpose for estimating cure rates with PSA 0.2 ng/ml for all treatment methods for prostate cancer (Table 1) is to be able to compare cure rates using a standard definition of cure for prostate cancer (apples-to-apples) so that men can make reasonable comparisons between treatment methods and be able to decide for themselves which method to choose.