For TCGA triple-negative BRCA data, you can follow this: How to download triple negative breast cancer RNA-seq fpkm data from GDC.
For other data, look on these data repositories:
There is also a lot of other cancer data available at the ICGC Data Portal. This is hosted by the ICGC and links to TCGA data at the GDC, and PCAWG (Pan-cancer Analysis of Whole Genomes) data at other global sites. For these, you will have to request access.