The immune contexture of primary and metastatic human tumours

• The immune contexture is a powerful tool to predict patient's clinical outcome.
• Chronic inflammation can foster cancer development and tumour growth.
• An adaptive immune response predicts longer survival in most cancers with some exceptions such as kidney cancer and Hodgkin lymphoma.
• Immune contexture can be strongly influenced by tumour-originating factors.
• Immune contexture is preserved during the metastatic process and conserves its prognostic value.

A tumour grows in a complex microenvironment composed of stromal cells, lymphoid and myeloid cells, vascular and lymphatic vessels, and the resultant cytokine and chemokine milieu. In most primary tumours, a strong Th1/cytotoxic T cells infiltration correlates with a longer survival. This beneficial effect can be hampered by the presence of M2 polarized macrophages and high VEGF production. Recent studies revealed that the pattern of the tumour microenvironment remains a major prognostic factor even in the metastatic lesions, while been reproducible between the primary and metastatic tumour. Nevertheless the prognostic impact of the Th1/cytotoxic T cell infiltrate could be different according to the origin of the primary tumour. This model highlights a novel tumour cell-dependent immune contexture that predicts patient's clinical outcome and has implications in the use of immunotherapies.