Endogenous transmethylation processes proceed via formaldehyde. Endogenous formaldehyde can be found in special bounded forms in animal tissues. The aim was to find non-invasive methods to help establish an early diagnosis of prostate cancer processes, and to search for a reliable examination repertoire to predict metastasis based on genomic hypomethylation that can be found in tumors. Fifty-eight age-matched patients suffering from prostate cancer and 26 healthy volunteers were enrolled in the study. Biochip technique was applied to quantify serum interleukins and growth factors. OPCL method served to determine mobilized formaldehyde, and fluorometric methods were applied to measure Zn- and free protoporphyrin concentrations in erythrocytes. Spectrophotometric measurements were carried out to evaluate redox homeostasis in plasma. There were no significant differences in most measured laboratory and immune parameters at different early stages of prostate cancer; at the same time, erythrocyte parameters, especially immobilized formaldehyde determination, were promising. The authors assume that hypomethylation detection in erythrocytes might become a predictive factor in the diagnostic panel in the near future. (doi: 10.5562/cca1748