Computed tomography 21 days after chemotherapy, three-dimensional estimates of metastatic volume and the need for surgery in patients with germ cell cancer

Objective To assess whether the response visible on computed tomography (CT ) 21 days after the first course of chemotherapy in patients with nonsemino matous germ cell tumour predicts the need for surgery and whether three-dim ensional (3D) reconstruction adds to the diagnostic accuracy. Patients and methods CT scans from 52 patients treated with cisplatin-based chemotherapy were assessed for tumour shrinkage by measuring the changes o f a one-dimensional (1D) measurement of the maximum transverse diameter, an d comparing CT scans before, 21 days after the first course and at the end of chemotherapy (1D method). In a subset of patients, using a special formu la, the 1D-derived 2D and 3D shrinkage (2D(der) and 3D(der)) were compared with four other computed or calculated methods (1D, 2D, 3D(calc), 3D(comp)) . Results At day 21, in 32 of 52 patients (62%) there was < 50% tumour shrink age using the 1D assessment; 21 of them (66%) needed surgery, compared with none of the 20 patients with > 50% tumour shrinkage by day 21 (chi(2) = 22 .83, P < 0.001). The 1D method showed significantly less shrinkage than all the other methods but when this was used to derive a 3D shrinkage, assumin g the mass to be spherical (3D(der)), it was not statistically different fr om that of 3D(comp). Conclusions The assessment of the response from 1D CT scan estimates 21 day s after initiating chemotherapy identifies a subgroup of patients who have a high probability of needing surgery. Although expected to be more accurat e, the 3D(comp) estimate of tumour shrinkage was no better than the 3D(der) estimate.