I am working on correlating clinical information with mutation data. I have downloaded clinical data related to Prostate Adenocarcinoma (PRAD) from TCGA firehose. But, survival times seem to be different from that of cBioPortal. For example, for TCGA-G9-6336, days_to_last_followup in TCGA is 1669, which comes to 54.87 months. But in cBioPortal, Overall Survival Time is given as 67.9 months. Any ideas which one is correct?