Predicting the response to preoperative radiation or chemoradiation by a microarray analysis of the gene expression profiles in rectal cancer

Abstract

Preoperative radiotherapy or chemoradiotherapy (CRT) has become a standard treatment for patients with locally advanced rectal cancer. However, there is a wide spectrum of responses to preoperative CRT, ranging from none to complete. There has been intense interest in the identification of molecular biomarkers to predict the response to preoperative CRT, in order to spare potentially non-responsive patients from unnecessary treatment. However, no specific molecular biomarkers have yet been definitively proven to be predictive of the response to CRT. Instead of focusing on specific factors, microarray-based gene expression profiling technology enables the simultaneous analysis of large numbers of genes, and might therefore have immense potential for predicting the response to preoperative CRT. We herein review published studies using a microarray-based analysis to identify gene expression profiles associated with the response of rectal cancer to radiation or CRT. Although some studies have reported gene expression signatures capable of high predictive accuracy, the compositions of these signatures have differed considerably, with little gene overlap. However, considering the promising data regarding gene profiling in breast cancer, the microarray analysis could still have potential to improve the management of locally advanced rectal cancer. Increasing the number of patients analyzed for more accurate prediction and the extensive validation of predictive classifiers in prospective clinical trials are necessary before such profiling can be incorporated into future clinical practice.

Expression Profiling of Rectal Tumors Defines Response to Neoadjuvant Treatment Related Genes

“…Furthermore, recent investigations suggest the importance not only of the tumor tissue itself but also of the immune system's dysregulation assessed in the peripheral blood of patients with LARC [18]. The lack of large-scale studies and the difficulty to understand and select which data would be informative and useful for a reliable clinical application offer further discussion and variability among the studies [19]. However, considering the utility of gene expression profiling in other tumors, like breast cancer, expression profiling of LARC could be crucial to improve the management of these patients.…”

Identification of biomarker microRNAs for predicting the response of colorectal cancer to neoadjuvant chemoradiotherapy based on microRNA regulatory network

“…Many genetic and molecular biomarkers have the potential to predict the responses of CRC to preoperative chemoradiotherapy, including p53, epidermal growth factor receptor, thymidylate synthase, p21, Bcl-2, and Bax [4]. Given the current controversial results, still no specific biomarkers can effectively distinguish responders from non-responders to preoperative radiotherapy or chemoradiotherapy [5].…”

Clinical utility of pretreatment prediction of chemoradiotherapy response in rectal cancer: a review

“…Biomarkers of emerging interest include those associated with the epithelialto-mesenchymal transition and microsatellite instability [77]. The gene or microRNA expression profiling using microarray has been used to analyze hundreds of potential biomarkers and to select promising candidates [77,78]. Analyses of circulating tumor cells or circulating tumor nucleic acids have also identified potential predictive markers [79,80].…”