The outcome of the Chernobyl nuclear power plant (CNPP) accident was that a huge number of people were exposed to ionizing radiation. Previous studies of CNPP clean-up workers from Latvia revealed a high occurrence of age-associated degenerative diseases and cancer in young adults, as well as a high mortality as a result of cardiovascular disorders at age 45–54 years. DNA tandem repeats that cap chromosome ends, known as telomeres, are sensitive to oxidative damage and exposure to ionizing radiation. Telomeres are important in aging processes and carcinogenesis. The aim of this study was to investigate the long-term effect of protracted ionizing radiation exposure on telomere length in CNPP clean-up workers. Relative telomere length (RTL) was measured in peripheral blood leukocytes of 595 CNPP clean-up workers and 236 gender- and age-matched controls using real-time quantitative polymerase chain reaction (q-PCR). Close attention was paid to participation year and tasks performed during the worker's stay in Chernobyl, health status, and RTL differences between subgroups. Telomere shortening was not found in CNPP clean-up workers; on the contrary, their RTL was slightly greater than in controls (P = 0.001). Longer telomeres were found in people who worked during 1986, in those undertaking ‘dirty’ tasks (digging and deactivation), and in people with cancer. Shorter telomeres appeared frequently in those with cataract, osteoporosis, atherosclerosis, or coronary heart disease. We conclude that the longer telomeres revealed in people more heavily exposed to ionizing radiation probably indicate activation of telomerase as a chromosome healing mechanism following damage, and reflect defects in telomerase regulation that could potentiate carcinogenesis.

This study revealed that the incidence, prevalence and mortality rates increased between 1990 and 2012, and although the 5- and 10-year overall and cancer-specific survival rates improved over the reviewed period they still needed to get better.

Our objective was to determine: 1) whether the checkpoint kinase 2 (CHEK2) del5395 (g.27417113-27422508 del, NC_000022.11) is a founder mutation in the Latvian population, 2) if there is an association between CHEK2 del5395 mutation and cancer risk, and 3) and whether the CHEK2 del5395 mutation impacts cancer predisposition in Chernobyl disaster liquidators (the civil and military personnel who were called upon to deal with consequences of the 1986 nuclear disaster) as well as geriatric populations. We recruited 438 breast cancer patients, 568 colorectal cancer patients, 399 ovarian cancer patients, 419 prostate cancer patients, 526 healthy blood donors, 480 Chernobyl disaster liquidators and 444 geriatric cancer-free participants. DNA samples were isolated from blood samples and subjected to multiplex polymerase chain reaction (PCR). The truncation of del5395 was estimated by fragment size of the multiplex PCR.All groups were compared to the healthy blood donors using Fisher’s exact test. All p values were two-sided and the odds ratios (OR) calculated by two-by-two table. In cancer groups, the del5395 mutation was most frequently observed in the ovarian cancer group (1.00%, OR = 1.32). In control groups, the del5395 mutation was most frequent (0.76%) in the healthy donors, which exceeded its frequency in the Chernobyl liquidators group and the geriatric group by 0.01 and 0.08%, respectively. For all groups, the OR appeared to be >1 only in ovarian cancer patients. However, OR rates showed no statistical significance in either cancer or control groups, with the p value fluctuating within the range of 0.39-1.00. The CHEK2 gene del5395 is a founder mutation in the Latvian population, which, however, does not have a direct impact on genetic predisposition toward colorectal, breast, ovarian and prostate cancer.

Introduction The aim of this article was to evaluate bladder cancer (BC) incidence, mortality and survival trends in Latvia over the past 28 years. Material and methods Our study included patients diagnosed with BC between 1990 and 2017. The data were obtained from the national population-based cancer registry. Joinpoint regression analysis was used to identify points where a significant change in incidence and mortality trends occurred, accordingly with the patient’s gender and age. Relative survival (RS) was estimated by Ederer I and II methods. Results Altogether, 9589 patients with initial BC diagnosis were included in the study. The age-standardised (ASR) incidence rates (per 100,000) increased from 6.8 in 1990 to 12.5 in 2014 followed by a statistically insignificant decrease continuing up to 2017. The ASR BC mortality rates (per 100,000) also rose from 3.9 in 1990 to 4.4 in 2017. However, there was a decline in BC mortality trends in the age-group 40–59 with annual percentage change (APC) -1.1%. RS rates increased from 55.0 % in 1990–2000 to 59.0% in years 2013–2017. Conclusions This study revealed that the incidence and mortality rates have been gradually increasing over the past 28 years. The exception being cancer-specific mortality in the age group 40–59, which tends to decrease. Although the 5-year RS rates improved over the reviewed period, there is still plenty of room for improvement.

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