The study by researchers at the Bassett Research Institute of the Mary Imogene Bassett Hospital in Cooperstown, N.Y., and Thomas Jefferson University in Philadelphia, also found extended periods of nighttime darkness dramatically slowed the growth of the tumors, reported the Washington Times Sunday.
According to researchers, artificial light depletes levels of the hormone melatonin -- and many tumors are largely dependent on a nutrient called linoleic acid in order to grow, said study leader Dr. David Blask, a neuroendocrinologist with the Bassett Research Institute.
The study, published in the journal Cancer Research, says the findings might explain why female night-shift workers have a higher rate of breast cancer and why incidence of breast cancer is much greater in industrialized nations than in Third World countries.
