Nowadays, the high incidence of cancer makes people “fearful” of cancer, and any research reports on cancer are very eye-catching. In recent times, first the news of “red meat causes cancer” was exposed in the United States, then WHO warned that 115 substances such as Chinese salted fish are also carcinogenic, followed by “vegetable oil causes cancer”, which exploded the public opinion. Before that, there were reports that pressure, microwave ovens and cell phones caused cancer, which made many people worry about what we can still eat and use in the future. First of all, we should have a full understanding of “carcinogenicity”. The classification of carcinogens is not based on the strength of carcinogenic ability, but on the degree of scientific evidence, including epidemiological surveys, dose-response relationships, animal experiments, etc. The clearer the evidence, the higher the level. The clearer the evidence, the higher the grade. At present, WHO classifies chemicals that have been studied for carcinogenicity into four levels: Level 1: carcinogenic to humans, Level 2A: likely to be carcinogenic to humans and carcinogenic to animals, Level 2B: likely to be carcinogenic to humans and carcinogenic to animals, Level 3: there is not enough evidence to determine whether they are carcinogenic, Level 4: non-carcinogenic; some carcinogenic factors such as cell phones are not too clearly evidenced and are only identified as 2B As for microwave ovens, there is no scientific evidence that they cause cancer. For example, the American Institute for Cancer Research believes that eating about 50 grams of bacon a day will increase the risk of colorectal cancer by about 21%, which is a 21% increase in risk, not a 21% risk of getting colorectal cancer. For example, processed meat and alcohol and tobacco are both first-class carcinogens, but the annual number of smoking-related cancer deaths worldwide is 1 million, alcohol-related cancer deaths are 600,000, while processed meat-related cancer deaths are only 34,000. Secondly, the carcinogenic ability of carcinogens is closely related to the dose, which determines the toxicity, and the dose includes exposure and exposure time. Even primary carcinogens such as ham, bacon and other processed meats are not carcinogenic if eaten once, but if eaten in large quantities every day, the risk of bowel cancer increases over time. Similarly, for class I carcinogens such as alcohol, long-term alcohol abuse increases the risk of liver cancer, but a small amount of alcohol, especially wine, is beneficial to health. Therefore, it is not scientific to talk about toxicity in terms of “dose”. Moreover, the human body has detoxification function, even if a small amount of carcinogenic substance is consumed, the liver can metabolize the carcinogenic substance through detoxification function, which will not lead to cancer. We should realize that the mechanism of cancer is very complicated, and it is the result of the long-term effect of internal and external factors such as genetic, psychological, occupational, environmental and dietary factors, and there is no single factor that necessarily leads to cancer. Therefore, in the face of many reports and rumors about “carcinogens”, we should treat them rationally and scientifically, and not be overly nervous or biased. To prevent cancer scientifically, we should follow the four principles proposed by the Victoria Declaration: reasonable diet, moderate exercise, smoking cessation and alcohol restriction, and psychological balance. Instead of choking on food and expecting to prevent cancer by eating certain anti-cancer foods or not eating certain “cancer-causing” foods, we should live our lives too hard, which is actually not good for our health.