Patterns of Metastatic Spread - Germ Cell Tumors of the Testis

With the exception of choriocarcinoma, which demonstrates early hematogenous spread, germ cell tumors of the testis typically spread in a stepwise lymphatic fashion. Lymph nodes of the testis extend from T1 to L4 but are concentrated at the level of the renal hilum because of their common embryologic origin with the kidney. The primary landing site for the right testis is the interaortocaval area at the level of the right renal hilum. Stepwise spread, in order, is to the precaval, preaortic, paracaval, right common iliac, and right external iliac lymph nodes. The primary landing site for the left testis is the para-aortic area at the level of the left renal hilum. Stepwise spread, in order, is to the preaortic, left common iliac, and left external iliac lymph nodes. In the absence of disease on the left side, no crossover metastases to the right side have ever been identified. However, right-to-left crossover metastases are common. These observations have resulted in modified surgical dissections to preserve ejaculation in selected patients (see section on Treatment, following).

Certain factors may alter the primary drainage of a testis neoplasm. Invasion of the epididymis or spermatic cord may allow spread to the distal external iliac and obturator lymph nodes. Scrotal violation or invasion of the tunica albuginea may result in inguinal metastases.

Although the retroperitoneum is the most commonly involved site in metastatic disease, visceral metastases may be seen in advanced disease. The sites involved in decreasing frequency include lung, liver, brain, bone, kidney, adrenal, gastrointestinal tract, and spleen.

As mentioned previously, choriocarcinoma is the exception to the rule and is characterized by early hematogenous spread, especially to the lung. Choriocarcinoma also has a predilection for unusual sites of metastasis such as the spleen.

Clinical Staging

Many clinical staging systems have been proposed for testicular cancer. Most, however, are variations of the original system proposed by Boden and Gibb (1951). In this system, a stage A lesion was confined to the testis, stage B demonstrated regional lymph node spread, and stage C was spread beyond retroperitoneal lymph nodes. Numerous clinical staging systems have also been suggested for seminoma. A stage I lesion is confined to the testis. Stage II has retroperitoneal nodal involvement (IIA is < 2 cm, IIB is > 2 cm). Stage III has supradiaphragmatic nodal involvement or visceral involvement.

The TNM classification of the American Joint Committee (1996) has attempted to standardize clinical stages as in Table 23-1.