Why is there cancer?

Cancer is a common malignant tumor in clinic. Because of its rapid progress and high mortality, it has caused great harm to patients and their families. In recent years, the incidence of cancer has increased significantly, which is the most dangerous factor endangering human health. The specific causes of the disease are not completely clear, the main is the cancer of a single cell, the body's immunity is low, so that the single cell gradually grows after cancer, breaks through the basal layer to produce distant metastasis, and causes systemic metastasis, resulting in patient death.