Lymphography in clinically localized prostate cancer.

Lymphography demonstrates the size, position, and internal architecture of the external iliac, common iliac, para-aortic, and paracaval lymph nodes. Importantly, the "surgical obturator" nodes are also routinely opacified because they are part of the external iliac chain. Analysis of the internal architecture permits detection of metastases in nodes of normal size, an advantage over cross-sectional imaging techniques. In a prospective study of 89 unselected, previously untreated patients with carcinoma limited to the prostate or periprostatic bed, lymphography was compared with histology of lymph nodes removed at surgical staging. The sensitivity was 53% (17 of 32), specificity 93% (53 of 57), accuracy 79% (70 of 89), and positive and negative predictive values were 81% (17 of 21) and 78% (53 of 68), respectively.