Practical Consequences Resulting from the Analysis of a21-Multigene Array in the Interdisciplinary Conference of aBreast Cancer Center

During the multidisciplinary planning of postoperative therapy after breast cancer, borderline cases can arise with no clear rationalefor or against adjuvant chemotherapy. In 50 hormone- receptor-positive, Her2neu-negative carcinomas of the breast with no or onlyminimal lymph node involvement (max. pT1a) we initiated an Oncotype DXmultigene assay in addition to the evaluation of usualparameters. In the oncology conference a vote for or against chemotherapy was taken on the basis of the conventional criteria fordecision-making before the test results were available. The final recommendation was made after the multigene test. In 32 breastcarcinomas(64%)alowrecurrencescorecouldbedocumented,while26(32%)showedanintermediateRSand3(6%)showeda high RS. In most cases the result of the test could validate the choice of therapy established using conventional criteria. In 5casestheinitialrecommendationforadjuvanttherapywasrevised, and in 3 cases chemotherapy was secondarily recommendedafter evaluation of the test results. Conversely, in some cases a low or intermediate risk constellation did not argue against arecommendation for adjuvant chemotherapy. Altogether, the results of our study do not indicate that a multigene assay should beused as a routine diagnostic tool. Instead a thorough compilation and careful analysis of conventional parameters for therapeuticdecision-making should take precedence, with special emphasis on histopathological and immunohistochemical results. In selectedcases, however, a multigene assay can be a useful tool in the deliberation for or against a therapeutic pathway.