Steyerberg et al developed a model with nomogram for predicting the likelihood of a male with prostate cancer having indolent disease. This can help identify a man who may be able to have less aggressive management. The authors are from Erasmus University in Rotterdam and the Cleveland Clinic.
Parameters:
(1) local prevalence of indolent prostate cancer (over range 20 - 50%)
(2) serum PSA in ng/mL (over range of 1 to 20 ng/mL)
(3) ultrasound prostate volume in cc (over range 20 to 80 cc)
(4) biopsy Gleason score
(5) total mm of cancer tissue in biopsy cores (over range 1 to 20)
(6) total mm of non-cancer tissue in biopsy cores (over range of 40 to 80)
total length of cores in mm =
= (total length of cancer tissue in mm) + (total length of noncancer tissue)
|
Parameter
|
Finding
|
Points
|
|
local prevalence
|
20%
|
-6
|
|
|
50%
|
0
|
|
Gleason score
|
2 + 2
|
0
|
|
|
2 + 3
|
1
|
|
|
3 + 3
|
4
|
points for local prevalence =
= (20 * (local percent) / 100) - 10
|
PSA
|
Points
|
|
1 to 6
|
(0.1186 * ((PSA)^2)) - (2.843 * (PSA)) + 17.33
|
|
6 to 20
|
(-0.2818 * (PSA)) + 5.632
|
points for ultrasound volume =
= (0.1 * (volume in cc)) - 2
|
Tumor Length
|
Points
|
|
1 to 5
|
(0.1237 * ((length)^2)) - (1.945 * (length)) + 10.67
|
|
5 to 20
|
(0.01778 * ((length)^2)) - (0.7408 * (length)) + 7.701
|
points for nontumor length =
= (0.1 * (length)) - 4
total score =
= SUM(points for all 6 parameters)
|
Total Score
|
Probability of Indolent Cancer
|
|
< 9
|
< 13%
|
|
9 to 17
|
(0.2933 * ((score)^2)) - (2.742 * (score)) + 13.91
|
|
17 to 25
|
(-0.2338 * ((score)^2)) + (14.48 * (score)) - 126.9
|
|
> 25
|
> 90%
|
Alternatively:
X =
= (0.25 * (total score)) - 4.196
probability of indolent cancer =
= 1 / (1 + EXP((-1) * X))
Alternatively:
The data can be entered into the formula given in the footnote to Table 4 on page 110.
