CA9 and renal cell carcinoma: Meta-analyses have also shown high tumour expression of CA9 is an adverse prognostic factor in multiple cancers: renal cell carcinoma [RCC] (n=2,611) (84), oral squamous cell carcinoma [OSSC] (n=1,616) (85), and head and neck [H&N] cancer (n=1,470) (86).