In humans, tumours alterations in the surface expression and/or function of HLA class I antigens are frequently found and equipt neoplastic cells with mechanisms to escape immune control. The aberrant expression of HLA class I molecules can be caused by structural alteration or dysregulations of genes encoding the classical HLA class I antigens and/or components of the HLA class I APM. The dysregulation of APM components could occur at the epigenetic, transcriptional or post-transcriptional level. Interestingly, none of the HLA class I and II alleles have been demonstrated to be associated with an inctreased incidence per se of any cancer. However, individual alleles are known to be overrepresented in certain cancers or correlate with survival, prognosis, higher tumour staging, grading, disease progression and failure to CD8 T cells based immunotherapies.