The theme of World Cancer Day 2015 is “Cancer prevention and control goals are not far away”, which advocates to gradually achieve early detection, diagnosis and treatment of cancer through establishing healthy lifestyles, early diagnosis and treatment, ensuring effective treatment, and maximizing patient survival treatment, so as to promote the development of cancer prevention and control. The development of cancer prevention and control. Why is cancer so difficult to treat When we were growing up, cancer and AIDS were the most horrible disease terms. If you ask me, which one will be attacked first, cancer or AIDS? My answer would definitely be AIDS. Why is cancer so hard to get rid of? In my opinion, there are three main reasons. The first reason is that cancer is an “endogenous disease”: the cancer cells are part of the patient’s body. For “exogenous diseases”, such as bacterial infections, we have antibiotics. The reason why antibiotics work well is that they are only toxic to bacteria and have no effect on human cells, so they can be used in very high concentrations to kill all the bacteria and leave the patient intact. It’s not so easy to fix cancer. Cancer cells are still human cells even though they have turned bad. So to fix them, it is almost like killing a thousand enemies and damaging 800, which is the “side effects” we often hear about. For example, traditional chemotherapy drugs can kill fast-growing cells, which is useful for cancer cells, but unfortunately, there are many normal cells in our body that are also fast-growing, such as the hair follicle cells under the scalp. Hair follicle cells are vital to hair growth, and while chemotherapy drugs kill cancer cells, they also kill hair follicle cells, which is why hair falls out in chemotherapy patients. Hematopoietic stem cells, which are responsible for blood production and maintaining the immune system, are also killed, so chemotherapy patients have a very weak immune system and are highly susceptible to infection. The epithelial cells of the digestive tract are also killed, so the patient has severe diarrhea, no appetite, etc., etc. Such serious side-effects make the doctors have to constantly weigh and even “compromise” between curing the cancer and maintaining the patient’s basic life. Therefore, the concentration of chemotherapy drugs must be strictly controlled and cannot be used all the time, but one course of treatment at a time. If chemotherapy drugs could be administered in high doses as consistently as antibiotics, cancer would have been cured. This is the main reason why I think AIDS will be overcome before cancer, after all, AIDS is an “exogenous disease” caused by the HIV virus. The second reason why cancer is so difficult is that cancer is not a single disease, but a combination of thousands and thousands of diseases. There are no two identical leaves in the world, and there are no two identical cancers in the world. Lung cancer, for example, is the new number one killer among cancers in China, with a 465% increase in incidence over 30 years. China now has nearly 600,000 lung cancer patients each year, and the United States has 160,000. People often ask me: Are there any new drugs for lung cancer in the United States? I say: Yes, but only for a very small percentage of patients. For example, Novartis’ newest anti-lung cancer drug, Ceritinib, was just approved by the FDA last week, and it works very well for about 1% of lung cancers. But why is it that the new drug we have been studying for so long is only effective in 1% of patients? Lung cancer is simply classified by pathology into small cell lung cancer and non-small cell lung cancer. Is that the only two types of lung cancer? No, it is not. We know that cancer is caused by genetic mutations, and the number of mutated genes in each cancer is more than one and varies widely. A recent systematic genetic sequencing study showed that the average number of mutations in lung cancer patients was close to 5,000 per person! The random combination of so many variables results in each patient being a little different. These 600,000+ lung cancer patients in China are actually more like 600,000 different diseases. Of course, this is not to say that we need 600,000 different drugs for lung cancer. Because out of 5,000 mutations, there are only a few mutations that are critical, and by capturing those few key genes, we can potentially develop more effective drugs. But in any case, the new drugs developed by pharmaceutical companies, even if they are panacea, can not cure all lung cancer patients. Going back to the question earlier, why is Novartis’ new drug Ceritinib effective in only 1% of lung cancer patients? Because Ceritinib targets the mutated ALK gene, and only about 1% of lung cancer patients have ALK gene mutation. (This drug is not yet available in China, but is currently in clinical trials in China, and we expect that in the near future, Chinese patients with ALK mutation lung cancer will be able to use this drug). Because of the diversity of cancers, drug companies are almost destined to develop drugs for only a small number of patients at a time, and the development cost of each new drug is 10 years +$2 billion! Such a large investment of time and money leads to slow progress, and it is a long way to go, if not a long way to go, to conquer all cancers. The third is the mutation resistance of cancer. This is common to both cancer and AIDS and is a headache for everyone. It is also the fundamental reason why we have not yet conquered AIDS. You’ve probably heard of superbugs. Before the advent of antibiotics, Staphylococcus aureus infections were fatal, such as sepsis. But after the advent of penicillin, S. aureus wimped out. But the evolution of living things is unbelievably amazing, and because we misused penicillin, at the point where it killed 99.999999% of the bacteria, one or both of them suddenly evolved resistance and they were no longer afraid of penicillin. So man invented other antibiotics, like vancomycin. But now there is already a Staphylococcus aureus that is resistant to both penicillin and vancomycin, which is a superbug. Biological evolution is a double-edged sword. Nature has given us this ability to adapt to different environments, but cancer cells not only retain the basic evolutionary ability, but they are stronger, and in response to the drugs we give them, the cancer cells are constantly changing and finding ways to evade the effects of the drugs. When Ceritinib was in clinical trials, it was found that many cancer cells discarded the mutated ALK gene after a few months of treatment and created new mutations to help the cancer grow. Such a rapid rate of evolution always makes me sigh at how small humans are in front of nature.