Gestational trophoblastic tumors in Norway, 1968-1997: patient characteristics, treatment, and prognosis

The aim of this study was to give an overview of the Norwegian population of gestational trophoblastic tumors (GTT), diagnosed during 1968-1997 and treated with chemotherapy at the Norwegian Radium Hospital (NRH), with regard to patient characteristics, treatment, and prognosis.

The cases were grouped according to a modified version of the WHO scoring system. Staging was performed retrospectively according to the systems adopted by FIGO. Survival estimates were calculated by the method described by Kaplan and Meier. Cox regression models were used to find the best classification system with regard to prognosis (disease-free survival).

A total of 141 cases, 106 invasive moles (IM) and 35 choriocarcinomas (CC), were diagnosed in Norway and treated with chemotherapy at the NRH in the period 1968-1997. Altogether, 56% of the patients were assigned to the low-risk category, 20% to the medium-risk category, and 15% to the high-risk category. Most cases were classified into the clinical stages I (69%) and III (23%). The overall 5-year survival rate was 96%. A more favorable prognosis was seen in patients diagnosed in the 1980s and 1990s compared with those diagnosed in the 1970s (P = 0.04). Five patients had progressive disease and died from the disease. Nine patients relapsed. The prognosis (disease-free survival) was more favorable for IM compared with CC (P < 0.01). The FIGO classification system seemed to be a better predictor of disease-free survival than the WHO scoring system.

This study showed that the prognosis of patients with GTT improved in the 1980s and 1990s in Norway, and that the FIGO system might be the best predictor of disease-free survival.