Additional information

The SEER database was investigated for patients treated in 2004 through 2006. The SEER database is a large national cancer database that encompasses more than 26% of the United States population. Since 2004 it has included pretreatment PSA and pretreatment clinical stage, along with detailed pathologic information, as part of
its standardized data collection (13). We identified 150,012 prostate cancer patients diagnosed from 2004 to 2006 within the SEER database. We excluded patients if they did not receive a radical prostatectomy, if prostate cancer was not their first and only malignancy, if their histology was other than adenocarcinoma, if they received preoperative radiation, if theirclinical stage was recorded as cT2 without further specification, or if they had missing
or incomplete or discordant clinical or pathologic data. Patients for whom prostate cancer was not their first and only malignancy were excluded to prevent the erroneous attribution of non–prostate cancer positive LNs to the original prostate cancer diagnosis. We also excluded patients if they had clinical stage cT1a or cT1b, or had cT3 or cT4 or clinically metastatic disease, to reflect the most common clinical situations of cT1c, cT2a, cT2b, and cT2c disease
and to improve the accuracy of our potential formula.
Formula was made using 1460 patients to build it and 1470 patients to validate it. 

Study Population

Total population size: 2930