There is a column called stage_event_gleason_grading which I expect to see the Gleason Score, and what you get are as follows:

> unique(df.tcga$stage_event_gleason_grading)
 [1] 6334  945  844  743  734  633 7435 1055 9453 9543 6243  954
[13] 7434 8534 7344 7343 7433 9454 6332 8443 7432 7345 8444 8354
[25] 8445  835 7340 9545  853

I'm wondering how to interpret them. For example, when it says 945, I guess it means 4+5=9, and 1055 means 5+5=10. But what do the (other) four-digit codes mean? Say 6334, 7434