Serological thymidine kinase 1 (STK1) indicates an elevated risk for the development of malignant tumours

The role of serum tumour markers is to reveal tumours not yet visible by imaging techniques. Here we examine the use of serum thymidine kinase 1 protein (STK1) in health screening.

Persons (n = 11,880) participating in health screening programs in China, during 2005-2007, were tested for STK1. STK1 was measured by a sensitive chemiluminescence dot-blot assay. Medical examination of participants was carried out in parallel.

The proportion of STK1-positive (> 2 pM) individuals was 0.5%, corresponding to the cancer incidence rate of China. No malignant cases were found in the STK1-negative group, but two pre-malignant and one malignant case were found in the STK1-positive group. The low frequency of malignancies found was probably due to the relatively young population (mean age 40.4 +/- 13.4 years). In the STK1-positive group, there were 24% of persons with benign diseases (breast, liver, kidney), 37% with proliferative tissues (breast, prostate), 13% with fatty liver, 9% with inflammatory reactions/virus infections (three hepatitis B virus-positive persons) and 17% showed other types of physiological changes not directly related to proliferation. In the STK1-positive group, a significantly (p < 0.001) higher proportion of persons with proliferation of breast and prostate tissues were found (37%), as compared to the STK1-negative group (18%). Furthermore, the mean ages among the groups of persons with STK1-positive values were between 5-8 years higher, as compared to the STK1 negative group, due to higher mean ages of persons with proliferative breast and prostate tissues. Thus, 83% of the STK1-positive persons had diseases (benign, proliferation tissues, fatty liver, helicobacter pylori-positive and hepatitis B virus-positive) related to malignancies.

STK1-values > 2 pM may indicate an early risk for development of malignancies years later.