Is there a role for pretherapeutic chemosensitivity testing in breast cance?

SummaryThe title of this paper poses a question to which the short answer must be “yes”. What oncologist would not wish to be in the enviable position of an infectious diseases physician, who can treat a patient with a serious infection knowing that the organism is sensitive to the antibiotic prescribed? Unfortunately, cancer cells are not as easy to grow as most bacteria and previous attempts to produce a feasible chemosensitivity assay for clinical use have been largely unsuccessful. Yet the rationale for such assays is sound: not all tumors of one histological type respond in the same way to the same agent. We know that this heterogeneity reflects the molecular phenotype. Over the last 8 years, a new tumor chemosensitivity assay (ATP-TCA) based on highly sensitive luminescence technology has been developed to the point where it is now entering phase III trials in ovarian cancer. Results in breast cancer are similarly encouraging, although as yet few patients have been treated prospectively according to the results of the assay. The assay has 97 % evaluability for surgical biopsies with 76 % concordance between clinical response and chemosensitivity. Results from neoadjuvant studies in which needle biopsies and tumor from the mastectomy specimen obtained after three cycles in six cases were tested show the rapid development of resistance in four cases to combination chemotherapy. However, nine courses of chemotherapy givenon the basis of the ATP-TCA resulted in partial or complete responses in all nine patients. Phase III clinical trials of ATP-TCA directed therapy against empirical therapyare in progress.