Low immunity is indeed prone to cancer, why do you say so? Because in fact, the activation of oncogene of normal cells often occurs in human body, which leads to malignant transformation of cells, but not everyone gets tumor, because the body has a set of efficient and strict immune surveillance system, which can detect the malignant transformation of tumor cells at any time and anywhere, and remove or correct them in time, so as to nip tumor in the bud. In the case of patients with low immunity, the immune surveillance mechanism has problems and is unable to detect and remove the malignant transformed cells in time, resulting in a significant increase in the incidence of tumors. The most obvious example is AIDS. The most notable feature of AIDS patients is a significant decrease in the number of CD4 positive T lymphocytes, leading to a significant impairment of cellular immune function and predisposition to malignant tumors such as Kaposi’s sarcoma.