Four important toxic factors in modern life are too much stress, too much sugar, too much alcohol, and smoking. All of them place an especially heavy burden on the body, even a healthy body. They usually come in combination, so that each one exacerbates the effect of the other. Taken overall, they form an obstacle on the road to recovery that should not be underestimated.
Stress, sugar, alcohol, and smoking not only increase your likelihood of developing cancer, they also undermine the success of any cancer treatment, make the side effects of the treatment worse, and reduce your chances of survival.