Oxidative stress in cancer

Increased oxidative stress is a common feature observed in many different types of cancer. Depending on the radical formed, its concentration, and cellular location where its generation occurs, reactive oxygen species (ROS) have multiple functions within tumor cells. ROS-induced macromolecule damage can contribute to tumor initiation. Low levels of ROS can initiate cellular signaling pathways that mediate tumor cell proliferation, survival and tumor progression to a metastatic phenotype. High levels of ROS initiate signaling pathways that mediate tumor cell death, but also contribute to formation of cancer stem cells that induce tumor recurrence. Understanding the multitude and complexity of ROS-regulated pathways in cancer cells and targeted modulation of intracellular ROS levels using antioxidants or chemotherapy at different stages of tumor progression may be an effective strategy for combination therapy.