Stage I: Patients have persistently elevated hCG levels and tumor confined to the uterine corpus. Stage II: Patients have metastases to the genital tract.
Stage III: Patients have pulmonary metastases with or without uterine, vaginal, or pelvic involvement. The diagnosis is based on a rising hCG level in the presence of pulmonary lesions viewed by chest radiography.
Stage IV: Patients have advanced disease and involvement of the brain, liver, kidneys, or gastrointestinal tract. These patients are in the highest risk category because they are most likely to be resistant to chemotherapy. Choriocarcinoma is usually present, and the disease commonly follows a nonmolar pregnancy.
Prognostic Scoring System In addition to anatomic staging, it is important to consider other variables to predict the likelihood of drug resistance and to assist in selecting appropriate chemotherapy (53). A prognostic scoring system proposed by the World Health Organization reliably predicts the potential for resistance to chemotherapy (Table 39.3).
Table 39.3 Scoring System Based on Prognostic Factorsa a The total score for a patient is obtained by adding the individual scores for each prognostic factor. Total score: <7, low risk; ≥7, high risk.
When the prognostic score is higher than 6, the patient is categorized as high risk and requires multimodal therapy, which includes intensive combination chemotherapy, and may also include surgery and radiation to achieve remission. Patients with stage I disease usually have a low-risk score, and those with stage IV disease have a high-risk score. The distinction between low and high risk applies mainly to patients with stage II or III disease.
Diagnostic Evaluation Optimal management of persistent GTN requires a thorough assessment of the extent of the disease before the initiation of treatment. All patients with persistent GTN should undergo a careful pretreatment evaluation, including the following: 1.
2.
Measurement of the serum hCG level 3.
Hepatic, thyroid, and renal function tests 4.
Determination of baseline peripheral white blood cell and platelet counts
The metastatic workup should include the following: 1.
2.
Ultrasonography or CT scan of the abdomen and pelvis 3.
CT or magnetic resonance imaging (MRI) scan of the head
When the pelvic examination and chest radiographic findings are negative, metastatic involvement of other sites is uncommon.
Liver ultrasonography and CT or MRI scanning will disclose most hepatic metastases in patients with abnormal liver function tests. CT or MRI scan of the head facilitates the early diagnosis of asymptomatic cerebral lesions. Chest CT scans may detect micrometastases not visible on chest radiography. Chest CT will demonstrate pulmonary micrometastases in about 40% of patients with presumed nonmetastatic disease (54).
In patients with choriocarcinoma or metastatic disease, hCG levels may be measured in the cerebrospinal ﬂuid (CSF) to exclude cerebral involvement if the results of CT scanning of the brain are normal. The ratio of plasma-to-CSF hCG tends to be lower than 60 in the presence of cerebral metastases (55). A single plasma-to-CSF hCG ratio may be misleading, because rapid changes in plasma hCG levels may not be reﬂected promptly in the CSF (56).
Table 39.4 Protocol for Treatment of GTN aLocal resection optional.
Pelvic ultrasonography appears to be useful in detecting extensive trophoblastic uterine involvement and may aid in identifying sites of resistant uterine tumor (57). Because ultrasonography can accurately and noninvasively detect extensive uterine tumor, it may help identify patients who would benefit from hysterectomy.
Hysterectomy is performed in all patients with stage I placental-site trophoblastic tumor.