From the current research progress, cancer is a worldwide problem that has not yet been overcome, and there are many reasons why cancer cannot be overcome, including the characteristics of cancer itself and whether patients receive timely treatment.1. Heterogeneity of cancer: This causes cancer not to be easily overcome, and this heterogeneity is mainly caused by the diversity of chromosomes and genomes. The same pathological type of cancer does not have the same molecular characteristics, which also leads to different treatment efficacy for cancers of the same pathological type. Heterogeneity is also an important cause of drug resistance problems in treatment, which can make cancer resistant to chemotherapy, targeted therapy and other drugs, and then recurrence, progression and metastasis can occur. 2. Not in the proliferation cycle: Since a large number of cancer cells are not in the proliferation cycle, that is, cells in the dormant state, i.e. G0 stage cells, and most anti-cancer drugs are ineffective against cells in the dormant stage Most anti-cancer drugs are ineffective against dormant cells. When anti-cancer drugs kill a large number of cells in the proliferation cycle, the dormant cells may be awakened and enter the proliferation cycle, which becomes the root cause of cancer recurrence and progression; 3. Patients do not receive timely treatment: many cancers usually do not have obvious conscious symptoms in the early stage, so it is difficult to detect them in the early stage without physical examination, but when cancer is accompanied by some obvious clinical symptoms, it is usually in the middle or even late stage. When cancer is accompanied with some obvious clinical symptoms, it is usually in the middle or even late stage, losing the chance of radical treatment, which directly makes it difficult to be cured. Due to the above reasons, cancer is still difficult to be overcome, but we believe that the development of science is endless and that cancer can be cured in the future.