Figure 1.

(a) The plotted two-phased mathematical equation $\mathrm{f}\left(\mathrm{t}\right)=\exp \left(-\mathrm{d}\times \mathrm{t}\right)+\exp \left(\mathrm{g}\times \mathrm{t}\right)-1$ was proposed by Stein et al. to reflect the sum of decay and subsequent growth of a recurrent solid tumor under therapy. An initial logarithmic decay may shrink the relative tumor size to subclinical dimensions. As soon as cell growth outnumbers decay, the tumor may re-grow to a clinical recurrence. The assumed tumor growth rate (g) constitutes the primary objective variable of the present study. (b) Plotted CA125-course of patient no. 164 throughout primary and recurrence therapy of a high-grade serous ovarian cancer high-grade serous epithelial ovarian cancer (HGSOC) patient undergoing platinum-based chemotherapy. The black lines demonstrate the respective growth rate estimates (g1 and g2) calculated applying the two-phased mathematical model, which were further evaluated for their predictive and prognostic values.