Background: Latest data from International Agency for Cancer Research shows that
breast cancer is the leading cancer site in women and is the leading cause of death among female
cancers. Induction of reactive oxygen species (ROS) and oxidative stress as a consequence of impaired
balance between prooxidants and antioxidants are suggested to be involved in induction and
progression of breast cancer. Cancer cells are found to exhibit higher levels of ROS compared to
normal cells. However increased antioxidant defence which balances the oxidative status within the
cancer cells suggests that high ROS levels may prevent tumorigenesis via various mechanisms.
These contradictory roles of ROS and oxidative stress in breast cancer let scientists investigate potential
oxidative stress modulators as anticancer strategies.
Conclusions: In the present review we address the mechanisms of ROS production in breast cancer
cells, the role of impaired oxidative status as well as the benefits of introducing oxidative stress
modulators in therapeutic strategies in breast cancer. This review is focusing more on melatonin
which we have been working on during the last decade. Our data, in accordance with the literature,
suggest an important role for melatonin in breast cancer prevention and adjuvant therapy.