Can Thymidine Kinase 1 Detect Small Invisible Malignant Tumours?

Abstract Objectives. Early detection of malignant tumour is a prerequisite for a successful treatment. Here we investigate if thymidine kinase 1 is more sensitive than imaging technology to discover small invisible malignant tumours.Material and Methods. The cellular concentration of TK1 was determined by an automatic chemiluminescence analyzer of magnetic particle immune sandwich minimum. The primary and secondary antibodies linked to the magnetic beads were chicken anti-human thymidine kinase 1 IgY-polyclonal antibodies (IgY). The minimum number of cells able to detect by the automatic chemiluminescence analyzer were determined based on the cellar TK1 concentration of low and high TK1 cell lines of known cell count.Results. The TK1 concentration of malignant cell was found to be 0.021 pg/cell. Assuming 200 pg of total protein/cell, TK1 corresponds to 0.01 % of the total protein/cell. The concentration of TK1 in human blood serum of malignant patients is in the range of 2-10 pmol/l (pM), corresponding to about 50 x106 growing cells that release TK1 into 5 litre blood. The limit visibility by imaging of a tumour is about 1 mm in diameter, corresponding to about 109cells of a cell diameter of 1µm. Conclusion. TK1 is more sensitive than imaging.