Molecular oxygen, a double-edged sword, is both a boon and a curse for the
existence of life. Oxidative stress is the disequilibrium between reactive oxygen
(ROS)-generation and elimination that inflicts cellular damage. Living cells can adapt
to the ever-changing internal or external stresses. However, they gradually lose their
radical-scavenging adaptability with persistent stress, which further increases during
neoplasia. Cancer cells, well adapted in pro-oxidative milieu, drive metabolic and
genomic reprogramming, which further escalates the oxidative load. This vicious cycle
promotes further carcinogenic alterations. Contrastingly, the same ROS is essential for
the oxidative-burst mediated anticancer host-defense. To sustain this redox pressure,
cancer cells hijack the intracellular antioxidants. Therefore, redox reorientation towards
enhanced responsiveness may selectively target malignant cells by ROS-enhancement
beyond tolerance leading to mortality. Carcinogenesis, a multistep process, requires
ROS during initiation, promotion and progression. However, supraphysiological ROS
may induce apoptosis in unmanageable malignancies. Interestingly cells possess an
evolutionary-conserved nature to get hormetically pre-conditioned by a transient ultralow
exposure of a stressor, which in higher dose may show the opposite effect.
Antioxidants are excellent chemopreventives and chemotherapeutics. Here, we have
condensed the possible anticancer modulation of oxidative stress by phytochemicals,
aiming at an insight for future strategies in cancer management.
Keywords: Anticancer Therapy, Antioxidant, Carcinogenesis, Dietary
Phytochemicals, Hormesis, Nuclear Factor (Erythroid-Derived 2)-Like 2 (Nrf2),
Oxidative Stressor, Prooxidant, Reactive Oxygen Species, Xenobiotic
Metabolism.
