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Original PSA 1044 at diagnosis 1/25

Casodex started 2/3

Lupron 2/17

PSA 103 on 3/28

PSA 34 on 4/19

Is there a calculation I can use to figure out the rate of decline? The first PSA was drawn after 53 days on treatment and then the 2nd PSA was drawn an additional 22 days later. I feel like the number should be lower. The rate of decline doesn't seems as fast but maybe that's because the first PSA was drawn after a longer period? How do people track their PSA? I am pretty poor at math

4 Replies

The rate of PSA decline after starting a particular treatment is not commonly over-analyzed by doctors and many patients. The fact that it is improving is often taken as a good sign. The quicker the better, perhaps, but it may be more of an art form as to the biological interpretation.

There are, however, on-line PSA Calculators that can be used with actual dates and PSA values to display and/or calculate PSA doubling time and velocity. You just select the dates and enter the PSA values, and the calculator does all the math.

Here is one at the Memorial Sloan Kettering Cancer Center website:

mskcc.org/nomograms/prostat...

Here is another one: (which may use a slightly different method, using the raw data)

doubling-time.com/compute-P...

(If you use the tools while a PSA is in decline, you will get negative numbers for doubling times, of course.}

Most people/physicians use the calculators to compare just the last few increasing PSA data points pairs, to get a "feel" for any trends. You can play around with the calculators all you want, just to get the hang of using them.

Charles

Simplest way is to take a piece of graph paper put the PSA on the vertical axis and days on the horizontal. Each time you have your PSA measured you plot a point. If the resulting curve is down to the right then you are OK, if it starts going up then you have to be concerned. I am not sure there should be concern with the two numbers you have. Sometimes you need a little patience.

The slope for the first 55 days was -17.8. For the next 22 days it was -3.14. Overall a slope of -13.47. This is the rate of change PER DAY.

I wouldn't read much into this. You have had what looks, to me as a great response. Your PSA has been dropping quickly and you will just have to wait to see what the nadir is.

Best.

Thanks! 😉