Micronuclei in peripheral blood lymphocytes as a possible cancer risk biomarker: a cohort study of occupationally exposed workers in Croatia.

AIM To describe the cohort of Croatian workers monitored for micronuclei in peripheral blood lymphocytes and validate predictive value of micronuclei for the risk of cancer development. METHODS Between 1985 and 1999, peripheral blood lymphocytes were analyzed with in vitro micronucleus assay in a cohort of 200 subjects occupationally exposed to genotoxic agents. The follow-up for cancer incidence and mortality was performed through the Croatian National Cancer Registry and records of occupational medicine physicians. Micronucleated cell frequency values were compared by Kruskal-Wallis test. RESULTS The median micronucleated cell frequency value in the cohort was 49 (range, 30-79) per thousand cells. Micronucleated cell frequency was significantly higher in men than in women, which could be attributed to the different distribution of exposures. Micronucleated cell frequency increased with age for both sexes. Smoking habit had no influence on micronucleated cell frequency. The follow-up identified four cases of cancer. Three of them belonged to the highest micronucleated cell frequency tertile. CONCLUSION Due to a small number of cancer cases, the predictive value of micronuclei for the risk of cancer development in the cohort of Croatian workers was not estimated, but 4 identified cases were more than expected in a similar non-exposed group. The Croatian cohort will contribute to the pooled analysis of the current European study of predictive value of micronuclei for the risk of cancer development.