OSCC Dataset downlod using TCGA biolink

Question

[Biogeek]

Hi Community! Can anybody help me with r code as I m a beginner in bioinformatics . I am trying to get Star count data from TCGA project for my RNA seq analysis. My cancer of interest is OSCC which is not directly available on GDC. For that I have to select primary sites and it comes under project HNSC. I am using TCGAbiolinks. However while using "GDC prepare"...how should I code for primary site" so that I will only get those specific cases.