Martini et al reported a nomogram for predicting seminal vesicle invasion (SVI) in a patient with prostate cancer. This risk can influence patient management. The authors are from Icahn School of Medicine at Mount Sinai in New York City, Vita-Salute San Rafaele University in Milan.
Patient selection: male with prostate cancer
Parameters:
(1) serum PSA in ng/mL over range from 0 to 20
(2) Gleason grade
(3) maximum percent of a core involved with cancer
(4) seminal vesicle invasion on MRI
points for PSA =
= 0.5 * (PSA)
Parameter
Finding
Points
Gleason grade
1
0
2 or 3
3.9
4 or 5
6.1
maximum percent
<= 50%
0
> 50%
2.9
seminal vesicle invasion
no
0
yes
5.0
score =
= SUM(points for all 4 parameters)
Interpretation:
• minimum score: 0
• maximum score: 24
• The higher the score the greater the risk of seminal vesicle invasion.
Score
Probability of Seminal Vesicle Invasion
< 3.3
< 1%
3.3 to 23.8
X = (0.33068 * (score)) - 5.6878
probability of SVI = 1/(1+ EXP((-1) * X))
> 23.8
> 90%
Performance:
• The area under the ROC curve is 0.865.
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