The main research objective of this study was to determine telomere length in peripheral blood leukocytes and redox status parameters (malondialdehyde - MDA, ischemia-modified albumin - IMA, paraoxonase 1 activity - PON1, and redox index) in serum of SCLC patients (before chemotherapy, after 2 and 4 cycles of chemotherapy) and healthy volunteers. Here, PON1 is linked to small cell lung carcinoma.