When samples in clusters 2, 3, and 4 were combined and compared to samples in cluster 1, the P-value was marginally significant (P-value = 0.116, Kaplan-Meier curve not shown) with the median OS of 733 vs. 3147 days.
The difference in OS between the four clusters was not significant (P-value 0.25) for the validation samples, but the Kaplan-Meier curve showed a trend for lower OS for samples in cluster 1 relative to the other clusters (Fig. 5b ) with the median OS of 733, not reached, not reached and 3147 days for the 4 clusters.