Correlation of pretherapy prostate cancer characteristics with histologic findings from pelvic lymphadenectomy specimens

Purpose: The purpose of this study was to identify pretherapy factors associated with pelvic lymph node involvement (LNI) in patients with localized prostatic carcinoma (CAP), and to develop a model that would allow for estimation of this risk at the time of initial diagnosis. Methods and Materials: Between January 1988 and December 1992, 2439 patients with clinical Stage T1a-3cN0-XM0 CaP underwent radical retropubic prostatectomy and bilateral pelvic lymph node dissection as sole initial therapy at a single medical institution. Preoperative factors were evaluated for their association with pelvic LNI in univariate and multivariate logistic regression analysis. A model was developed that incorporated independent predictive variables, and probability plots were generated to estimate the likelihood of pelvic LNI in the patient with a new diagnosis of localized CaP. Results: Within clinical tumor stage, three groups (T1a-2a, T2b-c, and T3) were identified in which the observed rate of pelvic LNI was distinctly different. Gleason primary grades were also combined (1-2, 3, and 4-5) because of a similar observation. Univariate analysis identified clinical tumor stage (p < 0.0001), Gleason primary grade (p < 0.0001), and serum prostate-specific antigen (p < 0.0001) as factors associated with pelvic LNI. Each of these variables retained independent significance (p ≤ 0.0002) in the multivariate model. Patient age (p = 0.12) and history of prior transurethral resection of the prostate (p = 0.36) were not found to correlate with this endpoint. Probability plots provided an estimate of the likelihood for pelvic LNI according to the combination of pretherapy clinical tumor stage, Gleason primary grade, and serum prostate-specific antigen level. Conclusion: Clinical tumor stage as determined by digital rectal examination, Gleason primary grade of the diagnostic biopsy specimen, and pretherapy serum prostate-specific antigen value can be combined to estimate the probability of pelvic LNI for the patient with a new diagnosis of localized CaP. This information may be of value in directing the pretherapy diagnostic evaluation, as an aid in radiation therapy treatment planning, and in the conduct of clinical research efforts.