Background: During the clinical process, it is difficult to judge the life cycle of cancer patients, but based on the spread speed of cancer cells, the approximate cycle can be calculated. Purpose: This study uses conventional mathematical statistics to track the spread of cancer cells in a certain number of cancer patients and uses mathematical models to calculate the approximate life cycle of the patients. Method: This article randomly selects the cancer cell proliferation of liver cancer as the main target from the overall population and then uses the impact of the cancer cell proliferation rate on the life cycle of 20 gastric cancer patients to obtain 50 data samples. The sample capacity is 20. This article estimates the population mean parameter based on the sample mean. It is based on describing the sample data and making inferences in the form of probabilities about the unknown quantitative characteristics of the statistical population.Rather, the sample data are inferred from observations of a random process over a limited period. Result: This article uses samples to infer (estimate) the population distribution parameters in many ways. This article will assume that the overall distribution obeys a certain known probability distribution, but some parameters of the distribution are uncertain. Conclusion: The spread speed of cancer cells does not completely affect the patient's life cycle. If resistance to targeted drugs can be resolved, cancer cells and normal cells can coexist, and patients can continue to survive.