in patients with response to therapy resulting in a smaller area under the curve of days 1-3 (AUC) than in those with progressive disease (p = 0.028). The other parameters did not indicate the response to therapy at the initial treatment phase. In conclusion, the course of nucleosomes (AUC) might be valuable for the early prediction of therapy response in preoperatively treated colorectal cancer patients. Introduction Colorectal cancer ranks as the third most common cancer in men and women. It

more »

... s the second leading cause of cancer death in the United States [1] . Besides surgery, therapeutic options include radiotherapy, chemotherapy and also a combination of both. In these systemic modalities, apoptosis is one of the main mechanism leading to the demise of cancer cells. Nucleosomes, which are complexes formed by an octamer of histones with DNA twisted around, are typical products of apoptotic cell death [2, 3] . They are the basic elements of chromatin that is, during apoptosis, cleaved into mono-and oligonucleosomes by endonucleases [4, 5] . These particles are packed into apoptotic bodies and Key Words Nucleosomes ؒ DNA ؒ Apoptosis ؒ CEA ؒ CA 19-9 ؒ CYFRA 21-1 ؒ Tumor marker ؒ Colorectal cancer ؒ Radiochemotherapy Abstract Apoptotic markers and tumor-associated antigens might be suitable to indicate the response to radiochemotherapy early. We analyzed the courses of nucleosomes, CEA, CA 19-9 and CYFRA 21-1 in 25 colorectal cancer patients during radiochemotherapy (4 postoperative, 13 preoperative, 8 local relapse therapy). Blood was taken before therapy, daily during the fi rst week, once weekly during the following weeks, and at the end of the radiochemotherapy. After a temporary decline 6 h after the fi rst irradiation, nucleosomes rose in most patients rapidly reaching a maximum during the fi rst days which was followed by a subsequent decrease. In patients receiving postoperative therapy after complete resection of tumor, nucleosome levels generally were lower than in patients with preoperative or relapse therapy. Correspondingly, CEA, CA 19-9 and CYFRA 21-1 levels of postoperatively treated patients were the lowest whereas those with tumor relapse had the highest ones. During preoperative therapy, lower nucleosome concentrations were found