title: Is overall survival still the primary endpoint in maintenance non-small cell lung cancer studies? An analysis of phase III randomised trials.
abstract: BACKGROUND
  In advanced non-small cell lung cancer (NSCLC), the increasing number of active compounds available in second line settings makes overall survival (OS) with maintenance treatment a not frequently observed endpoint. A literature review was conducted to examine whether post-progression survival (PPS) correlates with OS in maintenance trials.
  
  
  METHODS
  PPS was defined as median OS - median PFS. The authors used the coefficient of correlation (r) to assess the correlation between them. They also evaluated the surrogacy of PFS and OS.
  
  
  RESULTS
  Ten trials with 11 arms were identified. Overall, a stronger correlation was observed between OS and PPS [Spearman rank correlation coefficient (r) =0.75] than OS and PFS time (r=0.37). The correlation of differences in median PFS (ΔPFS) and median OS (ΔOS) is 0.64 (P=0.0326). The slope of the regression line is 0.76, indicating that a maintenance therapy producing a one-month gain in PFS will yield an estimated three weeks prolongation in OS.
  
  
  CONCLUSIONS
  PPS is strongly associated with OS because of intensive post-study further lines of treatment. However, improvements in PFS are moderately associated with improvements in OS. Hence, in this setting, PFS is a possible surrogate for OS.
authors: Azienda Ospedaliera Treviglio, Oncology department, Medical oncology unit, Piazzale Ospedale 1, 24047, Treviglio (BG), Italia.
authors: Fausto
authors: F
authors: Petrelli
authors: Azienda Ospedaliera Treviglio, Oncology department, Medical oncology unit, Piazzale Ospedale 1, 24047, Treviglio (BG), Italia.
authors: Sandro
authors: S
authors: Barni
keywords: Non small cell lung cancer; maintenance therapy; overall survival; post progression survival; progression free survival; surrogate endpoint