A COMPARISON OF 2 COMMERCIALLY AVAILABLE AN VITRO CHEMOSENSITIVITY ASSAYS

In vitro chemosensitivity assays (IVCAs) are expensive laboratory test s utilized to assist oncologists in the selection of chemotherapeutic regimens. Their utility is disputed; yet, these assays continue to be requested because of the importance of the information they can provid e and their scientifically logical approach. Therefore, we compared th e results of two assays offered to clinicians at our hospital; the ext reme drug resistance assay performed by Oncotech (OT) and the fluoresc ent cytoprint assays performed by Analytical Biosystems (AB). The two techniques used and the expression of assay results by the two compani es are discussed. Twenty neoplasms, all at least 3 cm in diameter and predominantly of breast and ovarian origin, were compared. OT performe d 74 drug assays on 17 tumors, while AB performed 194 assays on the co rreponding neoplasms; 3 neoplasms were insufficient for comparison. Ev aluation of the results revealed apparent disagreement on at least 44 drug assays with complete disagreement on at least 2 of the drugs test ed in 12 of 17 cases. In conclusion, based on available information, c omparisons between IVCAs show great variation in results; prospective studies are needed to evaluate commercially available assays for corre lation with clinical outcome, and results should be expressed so compa risons can be readily made. Though utility may be limited to tumors re sistant to standard therapy, cost and benefit to the patient will ulti mately determine the fate of these tests.