Predicting extracapsular extension of prostate cancer in men treated with radical prostatectomy: Results from the population based prostate cancer outcomes study

Purpose: We investigated whether clinical information routinely available i n community practice could predict extracapsular extension of clinically lo calized prostate cancer in men undergoing radical prostatectomy. Materials and Methods: We examined prostate cancer outcomes in a population based sample of 3,826 patients with primary prostate cancer in 6 regions o f the United States covered by the Surveillance, Epidemiology, and End Resu lts program. Stratified and weighted logistic regression was used to identi fy predictors of and probabilities for extracapsular extension of clinicall y localized tumors treated with radical prostatectomy. Results: Nearly 47% of men undergoing radical prostatectomy had extraprosta tic extension. The strongest predictors were elevated prostate specific ant igen (PSA) greater than 20 versus less than 4 ng./ml. (odds ratio 5.88, 95% confidence interval 2.90 to 11.15), Gleason score greater than 8 versus le ss than 6 (1.73, 1.04 to 2.87) and age greater than 70 versus less than 50 years (1.91, 0.98 to 3.70). Ethnicity and region were not associated with i ncreased risk of extraprostatic extension. A nomogram developed from our mo del predicts extracapsular extension ranging from 24% in men younger than 5 0 years with PSA less than 4 ng./ml. and a Gleason score of less than 7 to 85% in those 70 years old or older with PSA greater than 20 ng./ml. and a G leason score of 8 or more. If prostatectomy were limited to patients with l ess than 60% probability of extraprostatic extension based on the nomogram, 95% of those with organ confined cancers would undergo definitive surgery and 18% of those with extracapsular extension would be spared the morbidity of surgery. Conclusions: In a population based analysis of prostate cancer practice pat terns PSA, Gleason score and age are clinically useful predictors of extrac apsular extension. Although extracapsular extension may be an imperfect pre dictor of cancer outcomes, our nomogram provides more realistic probabiliti es for extracapsular extension than those based on institutional series.