Cancer is not simply a cellular disease in which a series of mutations impel uncontrolled cell growth. For an initial genetic injury to become a visible tumour, the tumoral cells must avoid the immune system's control. An international team led by Dr. Guido Kroemer, from the University of Paris Descartes and with few Spanish collaborators- including Laura Senovilla and a few researchers at the Institute of Oncology of the University of Oviedo (Guillermo Mariño, Antonio Fueyo and Carlos López-Otín)- have shown in a study published by the journal Science that the immune system can detect a genetic aberration known as tetraploidization which arises in the first stages of cancer. This disorder leads to the formation of cells with double chromosomes and constitutes the fundamental engine for the morphological and genetic diversity of malignant tumours.

The research team could show that the immune system is able to recognise and destroy tetraploid cells thus avoiding that the cancer precursor cells spread and develop into malignant tumours. The studies leading to examining mechanisms responsible for this powerful anti-tumor action of the immume system have revealed that the tetraploidization gives way to an important functional stress in the endoplasmatic reticulum, one of the main intracellular organelles. This stress causes molecular disorders on the surface of the tetraploid cells, changing their properties and facilitating their recognition and destruction by the immune system.

This work has some clinical implications which could be checked in patients with breast cancer treated with chemotherapy and whose therapeutic response seems to be determined by their immune guard againts cancer. Thus, those patients in whose first cycle of chemotherapy was detected an infiltration of their immune system's cells in their tumours, have responded to the treatment in a more favourable way. Furthermore, this positive response is linked to the selective elimination of those malignant cells with tetroploid characteristics and molecular signs of stress in their endoplasmatic reticulum.

On the whole, these new results underline the importance of the immune systems's guard againts cancer in its development and progression as it reduces carcinogenesis and determines the therapeutic response to the cancer treatments used currently.