Antiseptic toxicity to breast carcinoma in tissue culture: an adjuvant to conservation therapy?

Of 50 patients who had scrape cytology of the excision cavity after conservative surgery for breast carcinoma, 10 (20%) had malignant cells remaining in the cavity recognised by cytology. Of these patients, 18 had histological evidence of tumour at the resection margin, giving an accuracy of the cytology of 84%, a sensitivity of 56%, and a specificity of 100%. When assayed for cytotoxicity against a breast tumour cell line (MCF7) or human fibroblasts, chlorhexidine gluconate was the most effective of eight antiseptics or antitumour agents (100% cytotoxicity at a 1/10,000 dilution) in killing breast tumour cells and had 70% toxicity to human fibroblasts at the same dilution. Hydrogen peroxide appeared to be the most useful agent overall with 94% cytotoxicity to breast tumour cells with only a 12% cytotoxicity to human fibroblasts at a dilution of 1/1,000,000. We suggest that free malignant cells left in the cavity after conservative surgery for breast cancer may be a cause of local recurrence. They can be recognised by scrape cytology at operation and the topical use of antiseptics as cytotoxic agents may be beneficial and warrants further investigation.