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

BACKGROUND: 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. PATIENTS AND METHODS: 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.
RESULTS: 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.
CONCLUSION: STK1-values > 2 pM may indicate an early risk for development of malignancies years later.