Prostatic carcinoma: incidence and location of unsuspected lymphatic metastases.

Prospective pathologic staging by pelvic lymphadenectomy in 60 patients with clinically localized carcinoma of the prostate disclosed a high incidence (35 per cent) of clinically silent and unsuspected lymph node metastases. When present, metastatic disease was frequently bilateral (57 per cent) and most commonly involved the obturator-hypogastric lymph nodes (87 per cent). Micrometastases alone were found in 5 patients and the potential significance of this finding on survival is discussed. Although the presence or absence of metastases could not be accurately predicted by histologic analysis of biopsy or prostatectomy specimens, the finding of undifferentiated tumor, marked anaplasia and penetration through the capsule correlated positively with nodal metastases. Pelvic lymphadenectomy is a safe and important diagnostic tool in the accurate staging of these patients. Its widespread use is advocated in patients with clinical stage B1, B2 and C tumors prior to definitive therapy. Based on the prospective data generated in this study lymphatic metastasis appears to be an early event in the spread of prostatic cancer.