title: Progression-free survival, post-progression survival, and tumor response as surrogate markers for overall survival in patients with extensive small cell lung cancer.
abstract: OBJECTIVE
  The effects of first-line chemotherapy on overall survival (OS) might be confounded by subsequent therapies in patients with small cell lung cancer (SCLC). We examined whether progression-free survival (PFS), post-progression survival (PPS), and tumor response could be valid surrogate endpoints for OS after first-line chemotherapies for patients with extensive SCLC using individual-level data.
  
  
  METHODS
  Between September 2002 and November 2012, we analyzed 49 cases of patients with extensive SCLC who were treated with cisplatin and irinotecan as first-line chemotherapy. The relationships of PFS, PPS, and tumor response with OS were analyzed at the individual level.
  
  
  RESULTS
  Spearman rank correlation analysis and linear regression analysis showed that PPS was strongly correlated with OS (r = 0.97, p < 0.05, R(2)= 0.94), PFS was moderately correlated with OS (r = 0.58, p < 0.05, R(2)= 0.24), and tumor shrinkage was weakly correlated with OS (r = 0.37, p < 0.05, R(2)= 0.13). The best response to second-line treatment, and the number of regimens employed after progression beyond first-line chemotherapy were both significantly associated with PPS ( p ≤ 0.05).
  
  
  CONCLUSIONS
  PPS is a potential surrogate for OS in patients with extensive SCLC. Our findings also suggest that subsequent treatment after disease progression following first-line chemotherapy may greatly influence OS.
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Hisao
authors.initials: H
authors.lastname: Imai
authors.affiliation: Clinical Trial Coordination Office, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Keita
authors.initials: K
authors.lastname: Mori
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Kazushige
authors.initials: K
authors.lastname: Wakuda
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Akira
authors.initials: A
authors.lastname: Ono
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Hiroaki
authors.initials: H
authors.lastname: Akamatsu
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Takehito
authors.initials: T
authors.lastname: Shukuya
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Tetsuhiko
authors.initials: T
authors.lastname: Taira
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Hirotsugu
authors.initials: H
authors.lastname: Kenmotsu
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Tateaki
authors.initials: T
authors.lastname: Naito
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Kyoichi
authors.initials: K
authors.lastname: Kaira
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Haruyasu
authors.initials: H
authors.lastname: Murakami
authors.affiliation: Division of Diagnostic Radiology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Endo
authors.affiliation: Division of Diagnostic Pathology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Takashi
authors.initials: T
authors.lastname: Nakajima
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan ; Third Department of Internal Medicine, Wakayama Medical University, Wakayama, Japan.
authors.forename: Nobuyuki
authors.initials: N
authors.lastname: Yamamoto
authors.affiliation: Division of Thoracic Oncology, Shizuoka Cancer Center, Shizuoka, Japan.
authors.forename: Toshiaki
authors.initials: T
authors.lastname: Takahashi
keywords: Extensive small cell lung cancer; overall survival; post-progression survival; progression-free survival; tumor response