Pneumonia does not usually turn into cancer, and pneumonia and cancer belong to two different types of diseases. Pneumonia is an inflammation that occurs in the tissues of the lungs, including acute inflammation and chronic inflammation, as well as infectious inflammation and non-infectious inflammation. However, pneumonia in a narrow clinical sense means acute inflammation of the lung, and also mostly refers to infectious inflammation, which is inflammation of the lung caused by a variety of pathogenic bacterial infections. Cancer is short for malignancy, which is a neoplastic disease. Thus one is an inflammatory disease and the other is a neoplastic disease, and the pathogenesis of the two is completely different. Inflammatory disease is an inflammation that occurs in local tissues due to the involvement of multiple inflammatory cells, while cancer is a tumor, a malignant tumor with abnormal cell proliferation caused by genetic mutation, which has local manifestations but is a systemic disease, so pneumonia usually does not turn into cancer. However, if pneumonia occurs repeatedly in a certain area, there is a possibility of gene mutation leading to cancer under the chronic stimulation of inflammation, but the probability of this is very small.