Primary Prevention – Causal prevention. Its goal is to prevent the occurrence of cancer. Its tasks include researching the causes and risk factors of various cancers, taking preventive measures against specific cancer-causing and cancer-promoting factors such as chemical, physical, and biological factors, as well as internal and external disease-causing conditions, and taking measures against the healthy organism by strengthening environmental protection, appropriate diet, and appropriate physical education in order to promote physical and mental health. For individuals, this is stage 0, which is an important period of “preventing disease before it occurs”. Primary Prevention – Three Early Prevention. The goal is to prevent the development of primary disease. The task includes taking “three early” (early detection, early diagnosis, early treatment) measures against potential or hidden diseases before the appearance of cancer symptoms. In order to stop or slow down the progression of the disease, the disease can be reversed to stage 0 as early as possible and health can be restored. Primary Prevention – Rehabilitative prevention. Its goal is to prevent deterioration of the disease and disability. Its task is to adopt multidisciplinary comprehensive diagnosis (MDD) and treatment (MDT), correctly select the reasonable or even the best diagnosis and treatment plan, in order to extinguish the cancer as early as possible, try to restore the function, promote rehabilitation, prolong life, improve the quality of life, and even return to the society.