Testicular Choriocarcinoma Workup

Alpha-fetoprotein (AFP) is secreted by yolk sac elements; elevated levels of AFP are consistent with NSGCT. Choriocarcinoma could be a component of such a tumor, but AFP is within the reference range in pure choriocarcinoma. AFP has a serum half-life of between 5 and 7 days.

Human chorionic gonadotropin (hCG) is a glycoprotein with the same alpha unit as thyroid-stimulating hormone (TSH), follicle-stimulating hormone (FSH), and luteinizing hormone (LH). Therefore, the beta subunit must be assayed. Beta-hCG has a 24- to 36-hour half-life and is secreted by syncytiotrophoblast cells within the tumor. Beta-hCG levels are usually markedly elevated in pure choriocarcinoma. Persistently elevation of beta-hCG levels is defined as continued elevation of the tumor marker above the predicted levels based on serum half-life of 24-36 hours.^[6] This can also be applied to AFP, in which levels above that expected for the zero order kinetics of a 5- to 7-day expected half-life represent persistent elevation. From a clinical perspective, persistent tumor marker elevation represents residual disease. As such, more advanced treatment modalities (eg, chemotherapeutic) may be required.

Liver enzyme profile to include lactic acid dehydrogenase (LDH): Elevated levels of LDH may indicate bulky or advanced disease; however, the sensitivity and specificity are limited compared with beta-hCG and AFP. Rising levels after treatment may indicate relapse. Elevation of the remaining liver function tests may correlate with metastatic liver disease.

Placental alkaline phosphatase (PLAP): PLAP is elevated in some patients with seminoma and advanced disease; however, smoking and several other tumors also cause elevations; therefore, this marker not commonly used.

Scrotal ultrasonography

Any male with a palpable testicular mass should undergo scrotal ultrasonography. Other indications for ultrasonography may include acute scrotal pain, hydrocele, or other nonspecific scrotal pain, swelling, or mass.

Choriocarcinoma is associated with hemorrhage and necrosis and may appear more cystic, inhomogeneous, and calcified than a seminoma.^[7]

Abdominal CT scanning of the abdomen and pelvis with intravenous and oral contrast

In all other forms of testis GCT, CT scanning can be used to most commonly identify metastatic disease to the retroperitoneal lymph nodes, and it understages approximately 15%-20% of patients thought to have stage I.

In patients with pure choriocarcinoma, metastatic disease via hematogenous routes may skip the retroperitoneal lymphatics.

CT scanning of the brain

Choriocarcinoma is associated with brain metastases. In a review of 242 patients with metastatic germ cell testis cancer undergoing treatment with a multi-agent chemotherapy protocol, Vugrin et al (1979) found 38 cases of brain metastases.^[8] Among patients with pure embryonal carcinomas, 13% had brain metastases, compared to 83% of patients with pure choriocarcinomas. Furthermore, choriocarcinomas tended to have multiple brain metastatic sites with cerebellar involvement.

In almost all cases, pulmonary metastases preceded or coincided with brain metastases.

Chest radiography/chest CT scanning

Chest CT scan is indicated only for an abnormal finding on chest radiography; however, choriocarcinoma has a high metastatic rate, and CT scanning of the chest is usually indicated.

Bone scan

In an autopsy study by Bredael et al (1982), GCTs had bony metastases at autopsy, including seminoma (56%), mixed choriocarcinoma (35%), teratocarcinoma (30%), and embryonal carcinoma (24%); however, 0 of 6 cases of pure choriocarcinoma metastasized to the bone.^[9]

In pure choriocarcinoma, a bone scan can probably be omitted in the absence of bone pain.

Gross findings include a small hemorrhagic nodule with some grayish-white viable tumor at the periphery. Histology shows that choriocarcinoma contains both syncytiotrophoblastic cells and cytotrophoblastic cells in intimate association (see image below).

Syncytiotrophoblastic cells are responsible for beta-HCG production.

American Joint Committee on Cancer and the International Union Against Cancer staging systems are described below.

Testicular cancer staging system ^[10]

• Primary tumor (T)

  • pTx - Primary tumor cannot be assessed.
  • p0 - No evidence of primary tumor
  • pTis - Intratubular germ cell neoplasia
  • pT1 - Tumor limited to the testis and epididymis, no vascular/lymphatic invasion, may invade the tunica albuginea, no invasion of the tunica vaginalis
  • pT2 - Tumor limited to the testis and epididymis, vascular/lymphatic invasion or tumor extending through the tunica albuginea with involvement of the tunica vaginalis, invades beyond the tunica albuginea or into the epididymis
  • pT3 - Tumor invades the spermatic cord with or without vascular/lymphatic invasion.
  • pT4 - Tumor invades the scrotum with or without vascular/lymphatic invasion, invades the scrotum
• Regional lymph nodes (N)

  • Clinical
    • Nx - Nodes not assessed
    • N0 - No regional lymph node metastasis
    • N1 - Lymph node mass or multiple lymph node masses less than or equal to 2 cm in greatest dimension
    • N2 - Lymph node mass or multiple lymph node masses greater than 2 cm but less than or equal to 5 cm in greatest dimension
    • N3 - Lymph node mass greater than 5 cm in greatest dimension
  • Pathologic
    • pN0 - No evidence of tumor in lymph nodes
    • pN1 - Lymph node mass less than or equal to 2 cm in greatest dimension, 5 or fewer nodes positive
    • pN2 - Lymph node mass greater than 2 cm but less than 5 cm in greatest dimension, more than 5 nodes positive, evidence of extranodal extension of tumor
    • pN3 - Lymph node mass greater than 5 cm in greatest dimension
• Distant metastases (M)

  • M0 - No evidence of distant metastases
  • M1a - Nonregional nodal or pulmonary metastases
  • M2b - Nonpulmonary visceral metastases
• Additional staging systems are well discussed by Prow (1998).^[11]

Table 1. Serum Tumor Markers (S) (Open Table in a new window)

Table 2. Stage Grouping (Open Table in a new window)