Stephenson et al developed a nomogram for predicting the probability of being recurrence free for prostate cancer following radical prostatectomy based on postoperative parameters. For a person who has been cancer free since surgery, the probability of being cancer free at 10 years after surgery can be predicted. The authors are from the Memorial Sloan-Kettering Cancer Center and the Cleveland Clinic Foundation.
Parameters:
(1) year of radical prostatectomy
(2) surgical margins
(3) extracapsular tumor extension
(4) invasion of seminal vesicles
(5) involvement of lymph nodes
(6) primary Gleason grade
(7) secondary Gleason grade
(8) preoperative PSA
|
Parameter
|
Finding
|
Points
|
|
surgical margin
|
negative
|
0
|
|
|
positive
|
9.35
|
|
extracapsular extension
|
no
|
0
|
|
|
yes
|
20.8
|
|
invasion of seminal vesicles
|
no
|
0
|
|
|
yes
|
22.62
|
|
lymph node metastases
|
no
|
0
|
|
|
yes
|
10.25
|
|
primary Gleason grade
|
1 to 3
|
0
|
|
|
4 or 5
|
32.9
|
|
secondary Gleason grade
|
1 to 3
|
0
|
|
|
4 or 5
|
13.57
|
Scoring the year of the radical prostatectomy is a bit ambiguous, especially for anyone having a prostatectomy after 2004. There seem to be 2 possible interpretations:
(1) Survival has been improving, so the points assigned per year reflect improvements in survival. If this interpretation is used, then no points are assigned for a prostatectomy performed after 2004.
(2) The points represent the number of years since the surgery, in which case the nomogram would be modified each year with a shift in dates (for example, a radical prostatectomy in 2005 would be awarded 0 points, etc.)
points for year of prostatectomy =
= 3.3 * (number of years since the prostatectomy))
points for PSA =
= (-1.831 * ((LOG10(PSA))^2)) + (21 * (LOG10(PSA))) + 65.58
total postoperative score =
= SUM(points for all of the parameters)
Interpretation:
• minimum score: 0
• maximum score: over 240
• The higher the score the lower the probability of cancer free survival at 10 years.
Interpreting the probability of 10 year survival requires referral to the nomogram in Figure 2, which is complex. Input is the period that a patient has been cancer free since the prostatectomy and the total postoperative score.
For example, a person who is cancer free at 5 years after radical prostatectomy has a probability of being cancer free at 10 years as follows:
|
Total Score
|
Probability of 10-Year Cancer Free Survival
|
|
0 to 82
|
> 99%
|
|
82 to 137
|
(-0.000029 * ((points)^2)) + (0.004828 * (points)) + 0.7904
|
|
137 to 201
|
(-0.000087 * ((points)^2)) + (0.01827 * (points)) + 0.0453
|
|
> 201
|
< 20%
|
