The First Evidence of Familial Lung Cancer in Latvia by Population Screening for Hereditary Cancer

Introduction. Lung cancer is the major worldwide cause of tumour lethality. Recently, the role of heredity in lung carcinogenesis has become an important scientific target. While there is ongoing search for the respective gene mutations, it was suggested that presence of at least 2 first-degree relatives with lung cancer should reveal the familial lung cancer. Aim of the study. We present the first documented evidence of familial lung cancer in Latvia by population screening data in order to improve the planning of early cancer diagnostics. Materials and methods. The investigation was designed as population screening for hereditary cancer. Family cancer history was obtained from 18642 adults in the Valka district (76.6% of the adult population). Data analysis and proband consultations were performed in Hereditary Cancer Institute. Hereditary cancer syndromes were diagnosed by clinical criteria. Results. Familial lung cancer syndrome was diagnosed in 13 probands, but suspected familial lung cancer syndrome (sFLC) - in 93 probands, corresponding to the frequency 0.6% (95% confidence interval (CI) = 0.5-0.7%). The frequency of lung cancer among blood relatives was 25.5% (95% CI = 19.3-32.8%) in definitive and 17.2% (95% CI = 15.0-19.7%) in suspected syndrome groups exceeding significantly the cumulative risk for EU population. Number of affected generations was significant for sFLC. The age of cancer onset did not influence the frequency of cancer. The data about the cancer course are described. Conclusions. The high frequency of lung cancer in the identified pedigrees supports the role of familial factors in the lung carcinogenesis as well as the practical value of our diagnostic criteria helping to identify high-risk group for intervention measures to prevent lung cancer.