Exposure to light-at-night increases the growth of DMBA-induced mammary adenocarcinomas in rats

Exposure to light-at-night increases the growth of DMBA-induced mammary adenocarcinomas in rats

Author(s): Cos S, Mediavilla D, Martinez-Campa C, Gonzalez A, Alonso-Gonzalez C, Sanchez-Barcelo EJ
Source: CANCER LETTERS Volume: 235 Issue: 2 Pages: 266-271 Published: APR 28 2006


Abstract: In order to assess whether light exposure at night influences the growth of mammary tumors, as well as the role of melatonin in this process, female rats bearing DMBA-induced mammary adenocarcinomas were exposed to different lighting environments. Animals exposed to light-at-night, especially those under a constant dim light during the darkness phase, showed: (a) significantly higher rates of tumor growth as well as lower survival than controls, (b) higher concentration of serum estradiol, and (c) lower nocturnal excretion of 6-sulfatoxymelatonin, without there being differences between nocturnal and diurnal levels. These results suggest that circadian and endocrine disruption induced by light pollution, could induce the growth of mammary tumors. (c) 2005 Elsevier Ireland Ltd. All rights reserved.