Relationship between solar activity, forest fire smoke and the incidence of tumors of the central nervous system in Russia

Background. Studying the causes of tumors of the central nervous system is necessary to increase the effectiveness of this pathology prevention. Aim. To study the relationship between solar activity and forest fire smoke and the incidence of tumors of the central nervous system in Russia. Material and methods. Data on the incidence of tumors of the central nervous system in Russia in 1990–2019 were provided by the Moscow Research Oncological Institute named after P.A. Herzen. Information on solar activity (average annual Wolf numbers) and the number of forest fires was obtained from open sources. A Pearson correlation analysis of time series of environmental factors intensity and morbidity was carried out in 11 iterations with a time delay of 0–10 years. The average values of connection strength and lags were calculated using the method of moments. Results. A relationship between the number of forest fires and the incidence of tumors of the central nervous system was identified in 34 regions. The average correlation coefficient at the age of 0–4 years was 0.543±0.042 (lag 5.6±2.2); in 0–14 years — 0.492±0.039 (lag 3.1±0.8), in 0–85+ years — 0.549±0.059 (lag 4.8±1.5). The connection between solar activity and the incidence of tumors of the central nervous system in the 1st decade of the study (1990–1999) was found in 39 regions of Russia, in the 2nd and 3rd decades — in 45 regions. The average correlation coefficient was 0.704–0.767. In the full-age (0–85+ years) population of Russia, a trend toward an increase in the strength of the connection was revealed over time: in the 1st decade (1990–1999) r=0.719; in the 2nd (2000–2009) r=0.871; in the 3rd (2010–2019) r=0.899. The lag value, on the contrary, decreased from 6 years in 1990–2009 to 3 years in 2010–2019. Conclusion. The incidence of central nervous system tumors in Russia correlates with the number of forest fires and solar activity. Further research is needed to clarify cause-and-effect relationships.