About 85% or more of human cancers are related to dietary and environmental factors. Among the many cancers, some people are susceptible to certain cancers, such as breast cancer, colon cancer, lung cancer, esophageal cancer, and retinal cell tumors. These cancers have more of a genetic predisposition than other tumors. Breast Cancer According to scientists’ surveys and studies, the average risk of women developing breast cancer in their lifetime is about 9%. Its incidence factors are related to genetic factors in addition to many other factors such as age, diet and obesity. It has been documented that in some families, breast cancer patients have been found in five consecutive generations. Among breast cancer patients, the role of genetic factors is more obvious especially if the cancer occurs in both breasts during menopause. Colon cancer This cancer is similar to breast cancer in that the environment plays a significant role in contributing to its development. However, there is a disease called familial multiple colon polyposis that can easily develop into bowel cancer. It has been observed that in families where a parent has colon cancer due to the above mentioned disease, nearly half of their children will have the possibility of developing the same type of cancer. Lung Cancer There are many environmental factors that cause lung cancer, the main cause is smoking and the early symptoms of lung cancer are not obvious, but genetic factors also play a role. It has been observed that if a person has a close relative who has lung cancer and smokes, the risk of lung cancer is 14 times higher than the average person. A survey by Japanese scholars proved that 35.8% of patients with squamous cell carcinoma of the lung had a family history; among female patients with alveolar cell carcinoma, up to 58.3% had a family history. They also found that women with a family history of lung cancer who smoked had more than five times the risk of the disease than those with no family history and those who did not smoke. Retinoblastoma This is an extremely malignant tumor that occurs in children, 90% before age 3, often bilaterally, with a family history. This malignant tumor is associated with a genetic defect. According to research, under normal conditions, retinal cells have an Rb gene, and when it is out of function or congenitally absent, the retinal cells proliferate abnormally, thus promoting tumor production. Other cancers similar to retinoblastoma include malignant tumors of the kidney. Although all the cancers listed above have a genetic predisposition to cancer, the occurrence of these cancers is not only familial, but also most of them are inseparable from poor diet and environmental factors, which are the result of their combined effects. Therefore, people with a genetic predisposition to cancer should pay special attention to cancer prevention. They should pay attention to the combination of work and rest, change the bad habits such as smoking and alcoholism, and also consider the choice of marriage and working environment to avoid the influence of harmful rays and toxins in the environment. At the same time, we should insist on receiving regular health checkups and genetic counseling to keep ourselves and our next generation informed of the risk of cancer and preventive measures. For some precancerous lesions, such as colon polyps, cystic hyperplasia of the breast, certain benign tumors and cervical erosion, they should be treated or surgically removed as early as possible to prevent them from happening.