Overall, our findings suggest that the optimal management of rectal cancer requires tailored treatment based on biomarker expression such as the two-protein MRE11/ATM panel described here, as well as clinicopathologic characteristics. Further elucidation of biomarkers that predict the response to radiotherapy and/or chemoradiotherapy will constitute important progress toward the individualized treatment of patients with rectal cancer. In this regard, we are continuing studies on ATM and MRE11 in independent datasets focusing on pre-treatment specimens in comparison to post-treatment specimens.