Charcoal labeling of mammary tumors in mice prior to chemotherapy and surgery

Presurgery labelling of breast tumours with a charcoal suspension for intratumour injection

Objectives. A main goal of neoadjuvant chemotherapy (CT) in locally advanced breast carcinomas (clinical size >3 cm) is to decrease the tumour volume to permit conservative surgery. In about 10% of the cases, the tumour nodule is not clinically palpable after CT and it is necessary to tattoo the initial site in order to guide the surgeon for the resection of any residual tumour. We have developed a charcoal suspension for injection into human breast tumours. The aim is to enable the pathologist to guide the surgeon during excision of the residual tumour, which is not otherwise visible, after CT. Pharmacological and toxicological studies in animals have indicated that the suspension is well tolerated.

Methods. We investigated the efficacy and tolerability of a charcoal suspension in a group of eight patients with a palpable breast tumour of clinical size 1.5-4 cm, which was removed 24 hours to 4 days after the injection of 1 mL of 4% charcoal suspension into the tumour.

Results. This preliminary clinical study shows that the injection of charcoal is well tolerated by patients and is a good method of tattooing tumour. The charcoal was seen in or at the periphery of the nodule in the surgical specimen. No inflammatory reaction or diffusion was observed.

Conclusions. Based on these results, this suspension appears suitable for tattooing breast carcinomas over a period of 3 months for patients programmed to receive preoperative CT.

Tattooing breast cancers treated with neoadjuvant chemotherapy

BACKGROUND

In breast carcinomas treated with neoadjuvant chemotherapy, intraoperative identification of residual tumors may be difficult. A well-tolerated, low-diffusion charcoal suspension has been designed to tattoo breast tumors. In this study, we investigated whether this tattooing technique is efficient for localizing the tumor after treatment with chemotherapy.

METHODS

In a series of 109 patients with large breast tumors, a 4% or 10% charcoal suspension was injected at the time of the initial biopsy before preoperative chemotherapy.

RESULTS

Tolerance was good. After three or four cycles of chemotherapy, 91 patients underwent conservative treatment, and the surgical specimen was examined intraoperatively. The charcoal was detected in 94% of the cases. The charcoal was seen in the nodule or at the periphery in the surgical specimen without any acute inflammatory reaction or diffusion.

CONCLUSIONS

On the basis of these results, this micronized charcoal suspension at a defined granulometry and a concentration of 10% seems to be ideal for tattooing breast carcinomas over a period of 3 months in patients in whom neoadjuvant chemotherapy is planned.

Charcoal suspension for tumor labelling modifies macrophage activity in mice

We have previously developed a charcoal suspension for injection into human breast cancers in order to facilitate their location during surgery. We observed that charcoal particles were ingested by intra and peritumoral macrophages, some of which carried the particles at some distance from the injection site. We studied the influence of the formulation parameters of the charcoal suspension for intratumoral injection on in vitro and in vivo activation and in vivo mobilization of mouse peritoneal macrophages after intra-peritoneal injection of 2 mL of each preparation. The influence of the charcoal origin (peat vs wood), granulometry, suspension vehicle (water for parenteral injection, vs saline), concentration and excipients were studied. Micronized peat charcoal in water for injection at the highest studied concentration reduced macrophage activation in vitro and in vivo. However, macrophage mobilization was weaker than after thioglycolate injection and did not seem to be charcoal dose-dependent. The additives incorporated in the charcoal suspension led in vivo to increased peritoneal macrophage activation and mobilization (mannitol, and glucose), only increased activation (polysorbate 80 and pluronic F68) or mobilization (dextran 40, egg lecithin, and cabosil), or inhibited both activation and mobilization (cremophor EL).

Formulation of a charcoal suspension for intratumoral injection. Study of galenical excipients

To tattoo human breast cancer prior to chemotherapy, radiotherapy, or surgery, thus allowing a better localization of the remaining tumor by the surgeon, we developed a formulation containing 10% charcoal suspended in water for parenteral preparations. The present study concerns a new step in the development of the charcoal suspension. We sought to determine whether the addition of various excipients could improve the formulation properties and affect the labeling of tumor by the suspension. We have tested surfactants (egg lecithin, polysorbate 80, Cremophor EL, and Pluronic F68), isotonisants (sugars such as glucose and mannitol), polysaccharides (dextrans 20 and 40), and Cabosil, a pyrogenated silica. Except for glucose and mannitol, which were added at a 5% concentration, the other excipients were added at a 0.1% concentration, they were dissolved in water for parenteral injection and sterilized at 120 degrees C for 20 min. We then measured diffusion in vivo in mammary tumor. In vivo, when injected intratumorally in mice, a greater diffusion of charcoal particles was noted within the tumor (in the case of egg lecithin, polysorbate 80, dextran 20 and 40, and glucose) and sometimes in some organs (e.g., Cremophor EL and mannitol). Pluronic F68 slightly improved the stability of the suspension and did not lead to marked diffusion at the injection site, but it showed slight toxicity and cannot be used in the formulation. We concluded that the best formulation was an aqueous 10% micronized peat charcoal suspension.