Global breast cancer seasonality

Abstract

Human breast cancer incidence has seasonal patterns that seem to vary among global populations. The aggregate monthly frequency of breast cancer diagnosis was collected and examined for 2,921,714 breast cancer cases diagnosed across 64 global regions over spans from 2 to 53 years. Breast cancer is consistently diagnosed more often in spring and fall, both in the Northern and Southern Hemispheres, regardless of presumable menopausal status (<or=50, >50). This seasonality is increasingly more prominent as population distance from the equator increases and this latitude dependence is most pronounced among women living in rural areas. Moreover, the overall annual incidence (2005-2006), per 100,000 population, of breast cancer increased as the latitude of population residence increased. These data make it clear that human breast cancer discovery occurs non-randomly throughout each year with peaks near both equinoxes and valleys near both solstices. This stable global breast cancer seasonality has implications for better prevention, more accurate screening, earlier diagnosis, and more effective treatment. This complex latitude-dependent breast cancer seasonality is clearly related to predictable local day/night length changes which occur seasonally. Its mechanism may depend upon seasonal sunlight mediation of vitamin D and seasonal mediation of nocturnal melatonin peak level and duration.

All sites but skin cancer incidences analyzed worldwide by sex, age, and skin type over time (1955-2007), advancing age, and UVB dose reveals important carcinogenic drivers

“…The incidence of female breast cancer is in excellent agreement with their incidences of all sites but skin cancer. Moreover, the observed seasonality of many cancers [62][63][64][65][66][67] might reflect the hormonal seasonal fluctuations of estrogen. [68,69] Thus, our findings add epidemiological support to the already existing biochemical evidence obtained from birth control pills and hormonal replacement therapy in females suggesting a carcinogenic role for estrogen [20] in many cancers of both sexes.…”

Breast cancer and socio-economic factors

“…Regan (2010), studying Sweden context, shows that the effect of culture, historical factors, women's level of literacy and religious composition are economically significant determinants of demand for the oral contraceptive pill. As far as the research on global breast cancer seasonality by Oh et al (2010) is concerned, these authors find that breast cancer increases as the latitude of population residence increases (i.e. distance from equator increases) and "suggest biologic rather than social root causes" This interesting result can be explained by an alternative socio-economic interpretation represented by the distribution of richer "SS.…”

“…ANOVA has confirmed the statistical significant diversity of the arithmetic mean of breast cancer incidence between countries of temperate zone (rich) and non temperate zone (poorer). Hence, the higher incidence of breast cancer associated to higher latitudes might be traced back to socio-economic factors of countries rather than biological root causes of the theory of Oh et al (2010).…”

“…In addition the cumulative risk of breast cancer is higher in temperate zone about 6.35 (average between North and South) vs. 2.6 of countries in non temperate zone Hence, this analysis seem to display that the systematic effect of higher incidence of breast cancer based on Age-standardized rate (ASW) could be due to some drivers of socio-economic factors, mainly localized in richer countries that will be discussed in the next section. In addition, ANOVA can provide an alternative interpretation of the theory of Oh et al (2010) on the influence of latitude on breast cancer, focusing on socio-economic factors rather than biologic root causes.…”

“…In addition, this research may provide an alternative interpretation to the theory of Oh et al (2010) on the influence of latitude on breast cancer, focusing on socio-economic factors rather than biologic root causes.…”