The causes of cancer are very clear, in professional terms, pathogenic microorganisms, there are four kinds. The first one is hepatitis B virus, which causes hepatitis B, chronic hepatitis B, cirrhosis and liver cancer, and this is clear; the second one is Helicobacter pylori, which was discovered by two Australian doctors in 1976 and later won the Nobel Prize, and it is the causative factor of stomach cancer; the third one is cervical cancer, called HPV virus, also called human papillomavirus, and this is also a clear factor. This is also a clear factor; the fourth is the EBV virus, which causes nasopharyngeal cancer to occur. These four are very clear pathogenic microorganisms that cause cancer.