Early dynamic transcriptomic changes as predictors of preoperative radiotherapy efficacy in patients with rectal cancer: a feasibility study.

With a view to developing novel biomarkers of the efficacy of radiotherapy in patients with rectal cancer, we measured gene expression profiles on biopsies taken before and during preoperative radiotherapy. Repeat biopsy did not increase toxicity. Radiotherapy induced the expression of genes involved in oxidative stress, signal transduction, apoptosis and immune response. Two rectum tumor biospsies for each patient (6 cases) : before RT and one hour after a dose of 7.2 Gy (4th fraction) during RT.