Z-score normalization to normal samples

[antass]

I'm exploring the TCGA Pan-Cancer dataset which includes 32 studies. What samples are used as background when I select expression with normalization to normal samples?

Are there adjacent normal samples available in all of the 32 studies? I'm struggling to find any detailed info on that. In one webinar, the z-score calculation with normals as reference is mentioned, but only in the MSK Prostate study.

Specifically, for my gene of interest, when I look at the Cancer Types Summary tab, the graph shows significant over expression in cholangiocarcinoma (94% of tumor samples have high mRNA status (z-score > 2)). Does this mean over expression of cholangio tumors as compared to

• only cholangio normals?
• only prostate normals?
• all normals in all studies (in which case I'd like to know which studies were included)?

Thank you very much for your help!