Lymphatic Metastases from Pelvic Tumors: Anatomic Classification, Characterization, and Staging

The spread of pelvic tumors to lymph nodes is an important means of tumor dissemination. Nodal metastases have important management and prognostic impact. Pelvic tumors usually metastasize first to regional lymph nodes, which are specific groups of nodes for each tumor, and are classified according to the TNM system as N-stage disease. If a pelvic tumor spreads to a lymph node outside of the defined regional nodes, this is considered M-stage disease, which usually results in upstaging of the disease to overall stage IV cancer and may potentially affect the patient's treatment options. Knowledge of the regional nodal spread of each tumor is essential in formulating effective search strategies for cross-sectional imaging studies performed for staging. Also important is correct description of the nomenclature of nodal metastases to facilitate proper staging. In this review, the patterns of regional nodal spread and N-stage classification are presented for carcinomas of the anus, bladder, cervix, endometrium, ovary, penis, prostate, rectum, testis, vagina, and vulva. Pelvic lymph node anatomy and nomenclature are reviewed with schematic illustrations and clinical examples from patients with pelvic tumors.