Correlation between side of palpable tumor and side of pelvic lymph node metastasis in clinically localized prostate cancer.

Of 411 patients with palpable but clinically localized (Stages B or C) adenocarcinoma of the prostate, 100 (24.3%) were found at complete bilateral pelvic lymphadenectomy to have one or more lymph nodes positive for metastasis. These patients were divided into five subgroups on the basis of the location of the palpable tumor at digital rectal examination: left side only, left predominantly, both sides, right side predominantly, or right side only. Among 35 patients with positive nodes and a palpable tumor limited to one side of the prostate (clinically unilobar), metastases were found in the ipsilateral pelvic lymph nodes in 29 (83%). Only 6 (17%) of the patients had contralateral metastasis alone. A unilateral pelvic lymphadenectomy (ipsilateral to the side of the largest palpable tumor, or on either side if the tumor were bilateral) would have detected 80% of the patients with positive lymph nodes, with a positive predictive value of 100% and a negative predictive value of 94%. Lymph node metastases in patients with clinically localized palpable prostate cancer are most likely to be found on the same side as the palpable tumor and are considerably less likely to be found on the contralateral side alone. If frozen section examination of lymph nodes or laparoscopic lymph node dissection is planned before definitive therapy for prostate cancer, the pelvic lymph nodes ipsilateral to the side of the palpable tumor should be removed first.