People of any age can develop cancer, but medical statistics have found that the incidence of most cancers tends to increase with age, and more than 51% of cancer patients are older than 65 years old. Why is there a higher incidence of cancer in older adults? Current research believes that there are several reasons: 1. Beyond the “cancer incubation period” It is now recognized that 80% to 90% of human cancers are directly or indirectly related to exposure to carcinogenic substances. After carcinogenic factors act on human body, cancer will not develop immediately, and there is a latent period before cancer occurs. This long process from exposure to carcinogenic substances to cancer development is called “cancer incubation period” in medical science, which is generally 10-40 years, and generally 20 years. Therefore, if one is exposed to carcinogenic substances frequently at the age of 20-30, the disease will not develop until after 40-50 years old. In this way, the incidence of cancer in middle-aged and old people is higher. 2. Lower immune function The immune function of normal human has 3 main features, namely, self-stability, physiological defense and immune surveillance function. The cells in human body are constantly mutated and cancer can occur when the number of mutated cells reaches a certain level. The responsibility of the immune surveillance function is to remove the mutated cells in time so that they do not reach the cancerous number. However, as the immune function gradually declines with age, the immune surveillance function also declines, and mutated cells cannot be removed in time, so cancer can easily occur. According to the research of Dr. Blackburn of the University of Minnesota, the immune surveillance function of human body against lesions is gradually reduced from the age of 40, and the weakening of immune function is conducive to the occurrence and development of tumor. 3, endocrine dysfunction In old age, the endocrine system is dysfunctional and the hormones in the body are unbalanced, so that certain hormones may continue to act on sensitive tissues, leading to abnormal proliferation of certain tissue cells and even malignant changes. 4.Increased susceptibility to carcinogens The aging of human tissue cells can increase their susceptibility to carcinogens, which is the key to the vulnerability of the elderly to cancer. At the same time, research also shows that the older you are, the more chances you have to be exposed to carcinogenic factors, and the impact of carcinogenic factors on your body will be greater and greater, for example, the longer you smoke, the more likely you will get cancer. 5. Influence of chronic diseases Many cancers occur on the basis of original chronic diseases, such as oral mucosal leukoplakia can develop into oral cancer, atrophic gastritis and gastric ulcer can become gastric cancer, rectal polyp can lead to rectal cancer, etc. Since there are many chronic diseases in the elderly, the chances of developing cancer are increased. Although the tissue decline of the elderly is unstoppable, it is still possible to avoid cancer attack. For example, they can actively exercise, improve their physical fitness and health, develop good hygiene habits, pay attention to balanced diet and nutrition, actively prevent and treat various chronic diseases to prevent cancer, do a good job in health care, and have regular medical checkups to strive for early detection of cancer and early treatment.