**5. Conclusions**

Cancer is a personal disease, for this reason, it needs special attention. The above-mentioned evidences have shown that antioxidant supplementation cannot safe at times. Researchers advocate two different opinions regarding using antioxidant in course of cancer treatment. The first opinion is traditional approach. It says antioxidants prevent the normal cell from oxidative damage and they induce toxicity and provide better survival rates. The second one shows the dark side of antioxidants. According to the second opinion: antioxidants are decreased the survival rates by triggering drug-resistance. When we consider these two opinions we can easily understand the requirement of this area.

The most urgent thing is clinical trials with larger sample size and long-term following. Evidence obtained from in vitro or in vivo studies cannot representative for the 3D organism. The effects of antioxidant supplementation can determine appropriate clinical trials. Antioxidants' interference in chemotherapeutic mechanisms is still unknown and clinical fails of therapeutic approaches regarding redox modulation are obvious.

In summary, antioxidant cancer therapy remains incapable. ROS scavengers must give place to antioxidant inhibitors. ROS-related cell death mechanism is a novel approach to provide the selective cell death. Further investigations will need to see the effectiveness of pro-oxidant cancer therapy.
