Institute of Physiology, Komi Science Centre, Ural Branch of Russian Academy of Science, Syktyvkar, Russia.
Chronobiol Int. 2011 Mar;28(2):155-62. doi: 10.3109/07420528.2010.541312.
According to the hypothesis of circadian disruption, external factors that disturb the function of the circadian system can raise the risk of malignant neoplasm and reduce life span. Recent work has shown that the functionality of the circadian system is dependent not only on latitude of residence but also on the region's position in the time zone. The purpose of the present research was to examine the influence of latitude and time zone on cancer incidence, cancer mortality, and life expectancy at birth. A stepwise multiple regression analysis was carried out on residents of 59 regions of the European part of the Russian Federation (EPRF) using age-standardized parameters (per 100,000) of cancer incidence (CI), cancer mortality (CM), and life expectancy at birth (LE, yrs) as dependent variables. The geographical coordinates (latitude and position in the time zone) of the regions were used as independent variables, controlling for the level of economic development in the regions. The same analysis was carried out for LE in 31 regions in China. Latitude was the strongest predictor of LE in the EPRF population; it explained 48% and 45% of the variability in LE of women and men, respectively. Position within the time zone accounted for an additional 4% and 3% variability of LE in women and men, respectively. The highest values for LE were observed in the southeast of the EPRF. In China, latitude was not a predictor of LE, whereas position in the time zone explained 15% and 18% of the LE variability in women and men, respectively. The highest values of LE were observed in the eastern regions of China. Both latitude and position within the time zone were predictors for CI and CM of the EPRF population. Latitude was the best predictor of stomach CI and CM; this predictor explained 46% and 50% of the variability, respectively. Position within the time zone was the best predictor of female breast CM; it explained 15% of the variability. In most cases, CI and CM increased with increasing latitude of residence, from the eastern to the western border of the time zone, and with increasing level of economic development within the region. The dependence of CI, CM, and LE on the geographical coordinates of residence is in agreement with the hypothesis of circadian disruption.
根据昼夜节律紊乱假说，扰乱昼夜节律系统功能的外部因素会增加恶性肿瘤的风险并缩短寿命。最近的研究表明，昼夜节律系统的功能不仅取决于居住地的纬度，还取决于该地区在时区中的位置。本研究旨在探讨纬度和时区对癌症发病率、癌症死亡率和出生时预期寿命的影响。使用年龄标准化参数（每 10 万人）作为因变量，对俄罗斯欧洲部分（EPRF）的 59 个地区的居民进行逐步多元回归分析，因变量包括癌症发病率（CI）、癌症死亡率（CM）和出生时预期寿命（LE，yrs）。使用地区的地理坐标（纬度和时区位置）作为自变量，控制地区的经济发展水平。对中国 31 个地区的 LE 进行了相同的分析。纬度是 EPRF 人群 LE 的最强预测因子；它分别解释了女性和男性 LE 变异性的 48%和 45%。时区位置分别解释了女性和男性 LE 变异性的另外 4%和 3%。EPRF 东南部的 LE 值最高。在中国，纬度不是 LE 的预测因子，而时区位置分别解释了女性和男性 LE 变异性的 15%和 18%。LE 值最高的地区在中国东部。纬度和时区位置都是 EPRF 人群 CI 和 CM 的预测因子。纬度是胃 CI 和 CM 的最佳预测因子；该预测因子分别解释了变异性的 46%和 50%。时区位置是女性乳腺癌 CM 的最佳预测因子；它解释了 15%的变异性。在大多数情况下，随着居住地纬度从时区的东部边界到西部边界的增加，以及该地区经济发展水平的提高，CI 和 CM 会增加。CI、CM 和 LE 对居住地地理位置的依赖性与昼夜节律紊乱假说一致。
