CT detection of retroperitoneal lymph node metastases in patients with clinical stage 1 testicular nonseminomatous germ cell cancer: Assessment of size and distribution criteria

OBJECTIVE. Patients with nonseminomatous germ cell cancer of the testis with no evidence of metastatic disease after orchiectomy may be managed with either retroperitoneal lymph node dissection or surveillance. The present retrospective study was undertaken to determine the accuracy of CT for revealing retroperitoneal lymph node metastases in patients with newly diagnosed clinical stage 1 testicular nonseminomatous germ cell cancer of the testis when smaller size criteria (smaller than 10 mm) are applied and to test the hypothesis that CT-revealed anterior retroperitoneal lymph nodes are more likely to correlate with metastases than are posterior lymph nodes. MATERIALS AND METHODS. Abdominal CT scans obtained before surgery in 70 patients were reviewed by three observers who were unaware of the results of retroperitoneal lymphadenectomy. The sizes and sites of all lymph nodes measuring larger than or equal to 4 mm were recorded. Each CT scan was judged as positive or negative for retroperitoneal metastasis on the basis of the size of the largest measured lymph node at the expected metastatic site. Diameters of 4, 6, 8, and 10 mm were successively applied to each case as the criteria for a positive scan. RESULTS. Using a criterion of 10 mm or larger for metastases, we calculated a sensitivity of 37% and a specificity of 100%; with a 4-mm criterion, the sensitivity was 93% and the specificity was 58%, Receiver operating characteristic curves comparing the accuracy of CT for revealing similar-sized lymph nodes located anterior or posterior to a line bisecting the aorta differed significantly (p = .04) when the same criteria were applied to lymph nodes in both regions. CONCLUSION. False-negative rates were decreased from 63% using a size criterion of 10 mm to as low as 7% using a size criterion of 4 mm, with a corresponding decrease in specificity. Lymph nodes measuring larger than or equal to 4 mm, especially those located anterior to the mid portion of the aorta, should raise a suspicion of metastases.