Moderate Altitude Residence Reduces Male Colorectal and Female Breast Cancer Mortality More Than Incidence: Therapeutic Implications?

SIMPLE SUMMARY: Living at moderate altitudes has been reported to be associated with health benefits, including reduced mortality from male colorectal and female breast cancer. The aim of this study was to evaluate altitude-dependent incidence rates and to compare them with mortality rates of those cancers. We further explored whether altitude-associated differences in lifestyle behaviour exist. Analyses including all incidence cases and deaths over a 10-year observation period of an Alpine country (Austria) revealed that the age-standardized incidence and mortality rates of male colorectal cancer decreased by 24.0% and 44.2%, and that of female breast cancer by 6.5% and 26.2%, from the lowest (<251 m) to the highest (1000–2000) altitude level. The population-based survey indicated higher physical activity levels and lower body mass index for both sexes living at a moderate altitude compared to those living below 251 m. These observations may, in certain cases, support decision making when changing residence. ABSTRACT: Background: Living at moderate altitude may be associated with health benefits, including reduced mortality from male colorectal and female breast cancer. We aimed to determine altitude-dependent incidence and mortality rates of those cancers and put them in the context of altitude-associated lifestyle differences. Methods: Incidence cases and deaths of male colorectal cancer (n = 17,712 and 7462) and female breast cancer (n = 33,803 and 9147) from altitude categories between 250 to about 2000 m were extracted from official Austrian registries across 10 years (2008–2017). Altitude-associated differences in health determinants were derived from the Austrian Health Interview Survey (2014). Results: The age-standardized incidence and mortality rates of male colorectal cancer decreased by 24.0% and 44.2%, and that of female breast cancer by 6.5% and 26.2%, respectively, from the lowest to the highest altitude level. Higher physical activity levels and lower body mass index for both sexes living at higher altitudes were found. Conclusions: Living at a moderate altitude was associated with a reduced incidence and (more pronounced) mortality from colorectal and breast cancer. Our results suggest a complex interaction between specific climate conditions and lifestyle behaviours. These observations may, in certain cases, support decision making when changing residence.