Heterogeneity of chemosensitivity in human breast carcinoma: use of an adenosine triphosphate (ATP) chemiluminescence assay.

Cancer chemotherapy is currently given to patients with breast carcinoma on the basis of data from response rates in patients with advanced disease, or from the results of clinical trials of adjuvant therapy. However, individual tumours may vary in their response to particular cytotoxic drugs: optimal therapy for a population of patients may not be the correct treatment choice in individual cases. In this study we have used an ATP-based non-clonogenic chemosensitivity assay (TCA-100) to investigate the heterogeneity of chemosensitivity of human breast carcinoma to a number of cytotoxic drugs, both as single agents and in combination. Tissue was obtained from 33 patients. Most samples were excision biopsies, but sufficient tumour cells were obtained from three needle biopsies and three pleural effusions for assays to be performed. The results show wide variation in the response of individual breast tumours to single agents, but most tumours show sensitivity to the commonly used combination regimens. The TCA-100 assay may provide useful information to support the choice of regimen for breast cancer chemotherapy.