question about TCGA survival time values

[Sheltzer, Jason]

Hi,

I have a question about how to determine the days to death / days to last follow-up for TCGA patients. The GDAC analysis says “Survival time data is a combined value of days_to_death and days_to_last_followup.” As I understand it, this reports the number of days since the initial diagnosis. However, shouldn’t you take into account the day when the sample was collected, which is included as “days_to_sample_procurement” or similar? If the diagnosis happened years before the sample was collected, then the tumor at the time of sample collection could be very different from how it was at the time of diagnosis, thereby biasing any biomarker studies. Any help that you could provide would be greatly appreciated.

Thanks!

Jason

[Hailei Zhang]

In the TCGA data, there is no "days to sample procurement". We supposed that we collected the sample when the patients was diagnosed the cancer.  

Best,

Hailei