Objective: To investigate the reliability of preoperative diagnostics in predicting the true histopathological stage and grade of prostate cancer, and to examine whether lymph node (LN) metastases in unilateral prostate cancer are located unilaterally and therefore whether it is justified to dissect only the ipsilateral LNs in presumed unilateral disease.
Patients and methods: LN metastases in clinically localized prostate cancer are often located near the internal iliac vessels. They will be detected by extended or sentinel pelvic LN dissection (PLND). Both techniques might be time-consuming and require extensive surgical experience. In all, 564 men with impalpable or unilateral palpable prostate cancer and positive biopsy cores only in one prostate lobe had a radical prostatectomy (RP) combined with radio-guided PLND and in some cases an extended PLND.
Results: A median of six sentinel LNs (mean, seven) and six non-sentinel LNs (mean, seven) were dissected per patient; 52 of 564 men (9.2%) had positive LNs. Most men with unilateral disease had LN metastases on the same side of the pelvis. Comparing the clinical stage and grade with the tumour stage and grade of the RP specimen, there was a high percentage of upstaging and upgrading even in men with only one positive biopsy core.
Conclusion: Unilateral prostate cancer preferentially metastasizes to the ipsilateral pelvic LNs. Because there are a few cases of bilateral LN metastases even in unilateral disease, and as it is not possible to reliably predict unilateral disease on the basis of biopsy features, PLND only on the tumour-bearing side has a high risk of understaging, and would possibly leave LN metastases behind.