Purpose. We developed a charcoal suspension formulation to be injected intratumorally so that human breast cancers can be tatooed prior to chemotherapy. This deposit is intended to guide the surgeon at the time of the biopsy and resection, especially when the tumor nodule is not visible. The stain should remain in the tumor as long as the patient is on chemotherapy and should be harmless.
Methods. We studied on the effect on the nature of the charcoal, its granulometric profile, and its concentration. We then measured diffusion in vitro, in gel, and in vivo in experimental tumors.
Results. The formulation selected was prepared with a peat charcoal suspension in water for parenteral injections, with 50% of the particles measuring on average between 2 and 5 μm. The finest particles (<2 μm) seem to produce the greatest in vitro diffusion and are more readily phagocyted by macrophages and thus eliminated from the tumor by those cells.
Conclusions. This charcoal suspension has satisfactory formulation characteristics and diffuses the least, be it in vitro or in vivo, mainly due to the granulometric distribution of the suspension.