Abstract Background M30 and M65 are derivatives of cytokeratin 18 and released from the epithelial cell during cell death. These markers can be used to evaluate prognosis and chemotherapy response in several tumours. We evaluated serum M30 and M65 values in patients with advanced non- small-cell lung cancer (NSCLC) compared with those in a healthy group. Material and methods Thirty-two patients with advanced NSCLC and thirty-two healthy people were included in the study. Serum M30 and M65 values were measured by quantitative ELISA method. The best cut-off value for se- rum M65 was calculated by ROC analysis and then univar- iate analysis was performed to determine the importance of M65 value in predicting progression-free survival (PFS). Results There were no differences between mean serum M30 values between patients and controls (445.44±536.17 vs. 340.56±345.07, p=1). The mean serum M65 values were found to be significantly higher in patients than in healthy controls (1421.30±1662.59 vs. 648.85±341.17, p<0.001). The best cut-off value for serum M65 predicting PFS was 1311.64 U/l (AUC 0.58, sensitivity and specificity were 45.5% and 85.7% respectively). The patients with se- rum M65 values 1311.64 U/l had worse PFS than patients with serum M65 values <1311.64 U/l, p=0.01). There was no correlation between serum M30 value and PFS in the patient group (p=0.4). Conclusions Our results indicated that serum M65 values elevated in advanced NSCLC compared to a healthy con- trol group and elevated serum M65 level can predict PFS in patients. Keywords Non-small-cell lung cancer · M30 · M65 · Progression-free survival · Cut-off · Advanced stage Introduction Cytokeratin 18 (CK-18) is a cytoskeletal protein of the epithelium and released to circulation during apoptotic or non-apoptotic cell death of epithelial cells [1, 2]. Intact or caspase-cleaved forms of CK-18 are usually accepted as markers of cell death in the malignant transformation [1, 3]. In the circulation CK-18 fragments can be detected by M30 and M65 antibodies using enzyme-linked immunoab- sorbent assays (ELISAs) [4]. M30 is the monoclonal anti- body that recognises the caspase-cleaved CK-18 fragments so it is the selective biomarker of epithelial apoptosis [4, 5]. Monoclonal antibody M65 recognises all CK-18 frag- ments that contain full-length epitopes of the protein re- B. Oven Ustaalioglu · A. Bilici · M. Seker · M. Gumus Department of Medical Oncology Dr. Lutfi Kırdar Kartal Education and Research Hospital Istanbul, Turkey S. Ercan · A. Orcun Department of Biochemistry Dr. Lutfi Kırdar Kartal Education and Research Hospital Istanbul, Turkey A. Ozkan Department of Radiation Oncology Dr. Lutfi Kırdar Kartal Education and Research Hospital Istanbul, Turkey R. Ustaalioglu Siyami Ersek Thoracic and Cardiovascular Surgery Hospital Istanbul, Turkey B. Oven Ustaalioglu () Selimiye Mah, Şair Nesimi sok, Kardeşler Apt. No: 1, Daire: 4, 34668, Uskudar Istanbul, Turkey e-mail: basakoven@yahoo.com Clin Transl Oncol (2012) 14:356-361 DOI 10.1007/s12094-012-0808-0 RESEARCH ARTICLES Serum M30 and M65 values in patients with advanced stage non-small-cell lung cancer compared with controls Basak Oven Ustaalioglu · Ahmet Bilici · Serif Ercan · Asuman Orcun · Mesut Seker · Alper Ozkan · Recep Ustaalioglu · Mahmut Gumus Received: 6 July 2011 / Accepted: 4 August 2011