Mw. Kattan et al., Pretreatment nomogram for predicting the outcome of three-dimensional conformal radiotherapy in prostate cancer, J CL ONCOL, 18(19), 2000, pp. 3352-3359
Purpose: Several studies have defined risk groups for predicting the outcom
e after external-beam radiotherapy of localized prostate cancer. However, m
ost models formed patient risk groups, and none of these models considers r
adiation dose as a predictor variable. The purpose of this study was to dev
elop a nomogram to improve the accuracy of predicting outcome after three-d
imensional conformal radiotherapy.
Materials and Methods:This study was a retrospective, nonrandomized analysi
s of patients treated at the Memorial Sloan-Kettering Cancer Center between
1988 and 1998, Clinical parameters of the 1,042 patients included stage, b
iopsy Gleason score, pretreatment serum prostate-specific antigen (PSA) lev
el, whether neoadjuvant androgen deprivation therapy was administered, and
the radiation dose delivered. Biochemical (PSA) treatment failure was score
d when three consecutive rises of serum PSA occurred. A nomogram, which pre
dicts the probability of remaining free from biochemical recurrence for 5 y
ears, was validated internally on this data set using ct bootstrapping meth
od and externally using a cohort of patients treated at the Cleveland Clini
c, Cleveland, OH.
Results: When predicting outcomes for patients in the validation data set f
rom the Cleveland Clinic, the nomogram had ct Somers' D rank correlation be
tween predicted and observed failure times of 0.52. Predictions from this n
omogram were more accurate (P <.0001) than the best of seven published risk
stratification systems, which achieved a Somers' D coefficient of 0.47,
Conclusion: The development process illustrated here produced a nomogram th
at seems to predict more accurately than other available systems and may be
useful for treatment selection by both physicians and patients. J Clin Onc
ol 18:3352-3359. (C) 2000 by American Society of Clinical Oncology.