Long-term survival with non-proportional hazards: results from the Dutch Gastric Cancer Trial

Stat Med. 2005 Sep 30;24(18):2807-21. doi: 10.1002/sim.2143.


Randomized clinical trials with long-term survival data comparing two treatments often show Kaplan-Meier plots with crossing survival curves. Such behaviour implies a violation of the proportional hazards assumption for treatment. The Cox proportional hazards regression model with treatment as a fixed effect can therefore not be used to assess the influence of treatment of survival. In this paper we analyse long-term follow-up data from the Dutch Gastric Cancer Trial, a randomized study comparing limited (D1) lymph node dissection with extended (D2) lymph node dissection. We illustrate a number of ways of dealing with survival data that do not obey the proportional hazards assumption, each of which can be easily implemented in standard statistical packages.

MeSH terms

  • Aged
  • Biometry
  • Female
  • Humans
  • Lymph Node Excision / methods
  • Male
  • Middle Aged
  • Netherlands / epidemiology
  • Proportional Hazards Models
  • Prospective Studies
  • Randomized Controlled Trials as Topic / statistics & numerical data*
  • Stomach Neoplasms / mortality*
  • Stomach Neoplasms / surgery*
  • Survival Rate