Causes of rectal cancer

Rectal cancer is a malignant tumor that occurs from the junction of the sigmoid colon and rectum to the dentate line. It is one of the ten most common malignant tumors in my country, second only to gastric cancer in digestive tract tumors. 60.75% of colorectal cancers occur in the rectum, and 80% of rectal cancers can be palpated by digital examination. The cause of rectal cancer is still unclear, and it is mainly related to the following reasons:

① Chronic inflammatory ulcerative proctitis: due to long-term chronic inflammatory stimulation, repeated repair of ulcers, atypical hyperplasia and canceration. Domestic data show that the 20-year malignant rate of ulcerative proctitis that cannot be clinically controlled is 50%. Schistosoma proctitis: due to the deposition of schistosome eggs on the rectal mucosa, it may cause lesions, which has been confirmed by domestic scholars.

② The currently recognized precancerous lesions of rectal adenoma are familial adenomatosis and villous adenoma. Domestic literature reports that familial polyposis will turn into cancer after 10-15 years if not effectively treated.

③ Hereditary factors Recent research data have found that rectal cancer is highly hereditary. The chances of developing the disease in close relatives and close relatives with a family history of rectal cancer are significantly increased. Hereditary rectal cancer accounts for 14%. The transmission of gene changes can be manifested in the familial nature of tumors. It is mainly manifested as autosomal dominant inheritance. Rectal cancer occurs in several consecutive generations (vertical inheritance), and the genetic risk of men and women is equal. The age of onset is early, and the susceptibility of tumors in related organs of patients and their children is increased. Multiple primary cancers are common.

④ Dietary habits: Long-term consumption of a high-fat, low-fiber diet can increase the amount of 3-methylcholanthrene in the feces. This substance is a carcinogen. The reduction in fiber food intake can easily lead to constipation, which prolongs the contact time between high-concentration 3-methylcholanthrene and the colorectal mucosa, increasing the carcinogenic effect.

⑤Other factors.