Phagocytosis of cancer cells by mast cells in breast cancer.

BACKGROUND Mast cells (MCs) remain enigmatic more than 100 years after their discovery by Paul Ehrlich. Continuous research over the last 20 years has finally characterized the origin of MCs and determined many of the factors involved in MC differentiation and proliferation. MCs are traditionally known for mediating allergic reactions. In addition, these cells have been implicated in the pathogenesis of clinical conditions. Studies on the role of MCs in cancer have given contrasting results. MATERIALS AND METHODS This study included 50 cases of invasive ductal breast cancer not otherwise specified (NOS): 25 of them were highly hormone-receptive (HHR) cancers with estrogen and progesterone receptor values not lower than 50%, 25 were minimally hormone-receptive (MHR) cancers (<5%). In both groups, mast cells were quantified in the peritumoral area. Twenty cases of surgical interventions without cancer were included as controls. RESULTS It was found that in infiltrating ductal breast cancers having a high hormone receptor content (>50% for both estrogen and progesterone), there was a highly significant increase in MCs with respect to hypo-hormonal cancers in the same location and to controls (p<0.0001). MCs have thus proven to be very important cells because they have been found in sites playing an active role in opposing the aggression of the cancer cells (CCs). MCs may represent a protective factor of the human body against cancer aggresion. Two biological phenomena with the same goal can be observed: CCs are first phagocytized by MCs and then completely destroyed by karyocytoplasmic chemolysis through the action of toxicophore granulations. It was demonstrated that one or more CCs are surrounded by an MC's pseudopodia and then engulfed in its cytoplasm. The phagocytized cell progressively loses its chromatic and volumetric characteristics until complete achromia and almost complete reduction of its volume and consistency occur. The cell nucleus soon degenerates to pyknosis and becomes no longer detectable.