Colorectal cancer patients in the pre-surgical conversation doctors will almost always explain to patients the approximate 5-year survival rate of different pathological stages after tumor surgery, and often patients or their families will be puzzled when they hear the 5-year survival rate, and often ask: doctor, we spend so much effort, after surgery we can only live for 5 years? Faced with such a question, different doctors have different answers. Some will say: because we observe the patients for only 5 years, and after 5 years, there is no further observation and follow-up of the patients, so we can only count the survival rate for 5 years. Some doctors will say: malignant tumors that can survive for more than 5 years means that the effect is very good, so they will calculate the 5-year survival rate as an evaluation of the treatment effect? Is this answer correct? In fact, both of the above answers are incorrect, which means that their understanding of 5-year survival rate is not comprehensive and profound enough. 5-year survival rate is an indicator used in clinical practice to reflect the severity, progression or risk level of a certain type of cancer. 5-year survival rate is a statistical indicator, which refers to the percentage of patients who have been surviving a certain type of cancer for more than 5 years after treatment. For example, if 1,000 patients with stage III rectal cancer are treated with surgery and 500 are still alive after five years of follow-up, while the other 500 may die due to recurrence or metastasis, the five-year survival rate for this surgical approach to treating stage III rectal cancer is 50 percent. So why choose five years rather than some other time as a criterion? This is because cancer is characterized by being difficult to be cured and still prone to recurrence and metastasis after treatment, and most of the recurrence and metastasis occur within 2 years after treatment, accounting for about 80%, while recurrence and metastasis in a few patients occur 3-5 years after treatment, accounting for about 10%. If most tumors do not recur within 5 years after treatment, the chance of recurrence is very small, so it is close to cure, which is equal to the clinical cure rate. Therefore, the five-year survival rate essentially represents the long-term survival rate of patients, and the five-year survival rate is often used to represent the effect of cancer treatment. This is the result of statistical analysis of big data. Through the statistical index of five-year survival rate, we can grasp the malignant degree of the tumor and compare the treatment effect of different methods. For example, the five-year survival rate of pancreatic cancer with poor therapeutic effect is only 5%, but the five-year survival rate of differentiated thyroid cancer with good therapeutic effect reaches more than 90%. Therefore, the five-year survival rate can intuitively reflect the malignant degree of the tumor, and it should be further emphasized that the five-year survival rate of the same kind of tumor with different staging is also quite different. However, even for the same kind of tumor with the same stage, the five-year survival rate may be different with different treatments. Therefore, the five-year survival rate is also used to compare the effect of different treatments, and good treatments can get a high five-year survival rate, while bad treatments will have a low five-year survival rate. It is especially necessary to explain to the patients that the five-year survival rate is only a prediction for a certain overall population, which is a probability for doctors, definitely not the probability of a specific patient to live for five years. Even pancreatic cancer with a five-year survival rate of only 5% has patients who have survived more than five years after the operation (long term survival, clinical cure), and if detected at an early stage and standardized treatment, the patient may become one of the 5% of the patients. The five-year survival rate as a measure of tumor prognosis and treatment effect is meaningful to doctors, but as a probability to patients, whether the disease can be clinically cured to obtain long-term survival is the success and failure, i.e., clinically cured or recurrence of metastasis, the probability of the patient has no significance, the only way to get good treatment effect is to find out in early stage and standardize the treatment to face it bravely.