How many non-tumor samples needed for survival analysis?

Question

[jzhou]

Hi All, I've been working on my own survival analysis of PDAC, following the tutorial Survival analysis of TCGA patients integrating gene expression (RNASeq) data, but after I separated the tumor and non-tumor samples, I found that there were 179 tumor samples but only 4 non-tumor samples. I don't have too much experience with bioinformatics but I believe that 4 samples does not carry enough statistical weight even though they're normal samples to compare the cancer against and I was wondering if someone could confirm or correct me? If 4 samples is not enough, does anyone know how to find non-tumor samples in other databases like GEO? Thanks

Answer 1

[EagleEye]

For survival analysis there is no need for non-tumor samples, it should be carried out only using tumor samples. The non-tumor samples are important when you perform differential expression analysis.

[jzhou]

Thanks for a quick reply!