Assessing prognostic value of early tumor shrinkage and depth of response in first-line therapy for patients with advanced unresectable pancreatic cancer

BACKGROUND The prognostic potential of early tumor shrinkage (ETS) and depth of response (DpR) in pancreatic cancer (PC) is unclear. Here, we recruited 90 patients with recurrent and metastatic PC (RMPC) who had received chemotherapy as first-line therapy to assess the prognostic potential of these markers. METHODS ETS is characterized as a ≥ 20% depletion in the sum-of-the-longest-diameters (SLD) of measurable tumor lesions at 6-12 weeks than the baseline. DpR is the maximum shrinkage (%) from the baseline to nadir. We evaluated corrections in ETS and DpR with survival. RESULTS Of the 63 patients in which ETS assessment was possible, 21 (33.3%) achieved ETS. We found a significant association between the incidence of ETS and an improved rate of progression-free survival (PFS; 6.5 vs. 2.2 months; p < 0.001) and overall survival (OS; 12.1 vs. 6.0 months; p = 0.014). The median value of DpR was - 23.66%. DpR was also related to improved PFS (9.3 vs. 3.1 months; p < 0.001) and OS (18.2 vs. 7.3 months; p < 0.001). Patients who had distant metastasis, not local recurrence, with ETS showed markedly better outcomes. In a multivariate model, both ETS and DpR were independent predictors of OS in the whole population. CONCLUSIONS ETS and DpR may predict favorable outcomes for RMPC patients who had received chemotherapy as first-line therapy, independent of the agents used. Further studies on the exploratory analyses of the optimum ETS cut-off value in recurrent PC patients to predict favorable clinical outcomes are required.