Cancer is widely recognized as a significant contributor to global mortality. The origin of cancer is associated with both environmental and genetic factors. Cellular oxidative stress is commonly recognized as a main contributor to the development of pathophysiological disorders and cancer. Healthy cells employ multiple processes to regulate intracellular reactive oxygen species (ROS) levels and maintain overall redox equilibrium to prevent harm to DNA, proteins, and lipids. Minimal quantities of ROS can trigger cellular signaling pathways that facilitate tumor cells’ growth, survival, and advancement toward a metastatic state. Elevated levels of ROS trigger signaling pathways that facilitate the death of tumor cells while also promoting the development of cancer stem cells that provoke the recurrence of tumors. This suggests that instead of using antioxidants to treat cancer patients, it may be more effective to use pro-oxidants that intensify oxidative stress or hinder metabolic changes that provide tolerance to oxidative stress. The contrasting roles of ROS in suppressing and promoting tumor growth are examined to evaluate the efficacy of two distinct therapeutic approaches: augmenting or reducing ROS levels to combat cancer. Thus, oxidative stress and oxidative damage play significant roles in the advancement of cancer.