Variation in Treatment Effects

Figure 1

The figures on the left present the Kaplan-Meier survival plots for various adjuvant treatments for colon cancer from a trial conducted in the late 1980s.

Figure 1: Survival probabilities at each point in time for patients that were 61 years old and over.  It shows that patients who were in the 5-FU trial arm had an average survival probability that was twenty percentage points higher than patients in the other two trial arms at the 3,000 day point.

Figure 2

Figure 2: Survival probabilities at each point in time for patients that were 60 years or younger.  It shows that patients in each of the three trial arms had similar survival probabilities.

These graphs were produced using R and the "colon" data in the "survival package".  The patients were split into two equal groups by age.

The data is from the Moertel et al (1990) paper.  While the authors discussed some subset analysis.  The authors do not produce these graphs nor note the variation in survival by age.  

The main results presented in the original study are discussed in this post.