[Feasibility and relevance of tumor volumetry for stage classification and assessment of remission of germ cell tumors].

Although tumor load has proven to be the most relevant prognostic factor in disseminated germ cell tumors (GCT), methods to determine tumor volume for staging have not been studied so far. In a prospective study, we therefore measured the volume of metastases before and during chemotherapy in 27 patients with disseminated GCT. Abdominal tumor volume was calculated using a General Electric CT scan 8800. Total volume was determined by cumulation of 1 cm slices measured by a cursor. Pulmonary volume was calculated by taking each metastasis as a sphere using V = 0.523 x d3, where V = volume and d = diameter. We used linear regression analysis to determine the dependence of tumor markers on volume. Before chemotherapy, the median tumor volume of all patients was 237 (range 4-2690) cm3. The tumor volume was 1-100 cm3 in 30%, 101-500 cm3 in 41%, and over 500 cm3 in 29% of the patients. NED (no evidence of disease) was achieved in 8/8 patients presenting with a small (1-100 cm3) and 9/10 with a moderate (101-500 cm3) tumor volume. In contrast, only 1/8 with advanced tumor load (greater than 500 cm3) achieved NED. While there was a significant correlation between the initial and the residual tumor volume (P = 0.0024, r = 0.72), there was none between the tumor volume and alpha fetoprotein, beta human chorionic gonadotropin, and lactate dehydrogenase. These results suggest that radiological determination of tumor volume is a reproducible and accurate staging method.