Microarray-Genexpressionsanalyse zur Prädiktion der Response einer neoadjuvanten Radiochemotherapie bei lokal fortgeschrittenen Rektumkarzinomen

Abstract

Introduction: Neoadjuvant radiochemotherapy has become a standard treatment for locally advanced rectal cancer. Unfortunately, only app. 30%–50% of the patients shows histopathological response. Pretherapeutic response prediction would be of significant clinical relevance, but is currently not available. Patients and methods: During a phase II trial of neoadjuvant radiochemotherapy for patients with locally advanced rectal cancer pretherapeutic biopsies of 33 patients were available for microarray analyses. After RNA extraction and amplification gene chip analysis was done with the Human Genom U133 chip (Affymetrix). Results: Histopathological evaluation of response prediction showed a regression grade I or II (responder) in 39% (13/33) of the cases, in 43% (14/33) of the cases a regression grade III (partial responder) was found, and in 18% (6/33) a regression grade IV or V (non-responder). Statistical analysis based on 24 differentially expressed genes distinguished clearly between responders and partial or non- responders. Furthermore, a significant different gene expression profile consisting of 99 genes was found comparing responders and non-responders. Conclusion: Microarray based analyses of pretherapeutic biopsies identified responders and non-responders of neoadjuvant radiochemotherapy. This way of response prediction could help to individualize cancer therapy in the future.