At present, the antitumor effects of non-antitumor drugs are hotly speculated both in the professional field and among the general public. Due to the theoretical difference, the contents related to the antitumor effects of non-antitumor drugs should be separated between Chinese medicine and western medicine, and we only analyze the antitumor effects of non-antitumor western drugs that are currently hotly speculated. The research on antitumor effects of non-antitumor drugs has been conducted in the medical field for many years and has gradually shown a white-hot trend in recent years. Among them, there are three main categories of the most studied ones: non-steroidal anti-inflammatory drugs represented by aspirin, β-blockers and metformin. Let’s get to know them separately. Aspirin is an antipyretic and analgesic with a long history, having been marketed as early as 1899 for the treatment of colds, fever, headache, toothache, joint pain, etc. Over time, it has been more widely used in rheumatic diseases, as well as for the treatment of some types of ischemic heart disease, thrombotic diseases, etc. by preventing platelet aggregation. In recent years, some epidemiological studies have found that aspirin appears to have anti-tumor effects, especially in the prevention of digestive tract tumors, and further stratified and experimental studies have been conducted. One of them, a professor from Oxford University, has published several articles in the authoritative journal The Lancet, elucidating the short-term effects of aspirin on malignancy incidence and mortality, respectively, and also the effects of aspirin on the inhibition of malignant metastasis, which are more pronounced in digestive tract tumors. Beta-blockers are a class of drugs commonly used to treat cardiovascular diseases such as hypertension, and observational studies in recent decades have found that they may have some preventive effects on colorectal cancer. Many research units have conducted further observational studies on it. However, the results obtained are inconsistent, with some demonstrating that long-term oral administration of beta-blockers can reduce the risk of colorectal cancer in the population, while others confirm that long-term oral administration of such drugs does not reduce a person’s risk of developing colorectal cancer. Therefore, there is no consensus on whether beta-blockers can prevent the development of malignancies. Metformin is one of the most commonly used glucose-lowering drugs in clinical practice, and its mechanism of action is mainly to reduce the sugar content in the body by inhibiting the breakdown of hepatic glycogen, and to reduce the absorption of sugar in the intestine as well as to increase insulin sensitivity. A large number of clinical observations have found that metformin has the ability to reduce the incidence of tumors at certain sites and anti-tumor effects. Some experts have studied the mechanism of its hypoglycemic effect and found that it can prevent liver cancer by inhibiting hepatic fat synthesis; some studies have shown that metformin combined with antitumor drugs can significantly improve the antitumor effect on malignant melanoma. So far, we have basically understood the anti-tumor effects of the three most studied non-tumor drugs, however, can we apply such drugs to prevent tumors on this basis? I think the answer must be no, at least for the time being. Any drug has its specific action and metabolism, and what it can bring to human body after entering the body is not only therapeutic effect, but also its adverse reaction. For aspirin as a representative of the non-steroidal anti-inflammatory drugs, if long-term use as a tumor prevention, not only has a huge damage to the gastrointestinal tract mucosa, but also leads to abnormal coagulation, resulting in bleeding is difficult to control, etc., the two together, if the gastrointestinal tract mucosa damage bleeding and the body coagulation function is abnormal, bleeding can not be controlled in a short period of time, it may produce incalculable consequences. beta receptors Blockers not only have the effect of lowering blood pressure, but also have the effect of slowing down heart rate and reducing myocardial contraction depending on the distribution of its different receptors in the cardiovascular system. For normal people, lowering blood pressure, lowering myocardial contractility and lowering heart rate may mean insufficient blood and oxygen supply to important organs, such as insufficient oxygen supply to the brain, which may lead to drowsiness and inability to concentrate, and insufficient blood supply to the kidneys, which will increase the workload of the kidneys and may lead to irreversible kidney function abnormalities and even kidney failure over time. Metformin may also lead to abnormal lactic acid metabolism in the body while lowering blood sugar, and may lead to lactic acidosis when taken under long-term non-lowering blood sugar condition, which may be life-threatening due to acidosis in serious cases. Therefore, we should not blindly apply these drugs to prevent tumors based on the research data in the short term. Of course, these three non-antitumor drugs are not the only ones found to have antitumor effects, and we believe that with the development of science and technology, more non-antitumor drugs will be found to have antitumor effects, however, which ones we can use to prevent tumors and which ones we cannot is the task and mission of medical workers. Let’s wait for the good news!