Hello,
In several datasets (e.g. Breast METABRIC data, see attached screenshot) the disease-free survival is longer than the overall survival. Biologically thinking about it, disease progression happens before (or at the time of) death, not after death. So disease-free survival for each patient should be shorter than (or equal to) overall survival, not longer. Practically speaking, the DFS curve is generally shifted to the left of the OS curve. Or am I missing something obvious?
Could it be that the column headings are switched for some datasets? Another example is the Lung Squamous Cell Carcinoma (TCGA, Provisional) data.
The only other thing that I can think of is whether the disease progression data is (rather disproportionately) missing for those who had a shorter survival, and the analysis disregards the missing data, causing the DFS curve to shift to the right.
Any explanation would be helpful.
Thanks!