What Are Precancerous Lesions and Carcinoma In Situ?

The occurrence of malignant tumors is a gradual evolutionary process. Some benign lesions in certain organs of the human body are prone to abnormal cell proliferation with a tendency for malignant transformation. These lesions with a tendency for canceration due to abnormal proliferation are called precancerous lesions.

Precancerous lesions are a special stage before the occurrence of malignant tumors. Theoretically, all malignant tumors have precancerous lesions, but in reality, many precancerous lesions of malignant tumors are difficult to detect with current diagnostic methods. Additionally, not all precancerous lesions will develop into malignant tumors.

Common precancerous lesions include leukoplakia of the mucosa, chronic cervicitis, fibrocystic breast disease, multiple colonic polyps, chronic gastric ulcer and atrophic gastritis, chronic cholecystitis with gallstones, nodular cirrhosis, chronic skin ulcers, atypical hyperplasia of the epithelium in the endometrium and bronchial mucosa, etc.

Precancerous lesions themselves can be relatively stable for a long time, stop progressing, or even return to normal. Only a small portion of them, due to cancer gene mutations that gradually accumulate, will ultimately develop into malignant tumors. Recognizing precancerous lesions and actively detecting and treating them can prevent carcinogenesis and the occurrence of cancer.

Carcinoma in situ refers to epithelial malignant tumors confined to the skin or mucosa without invading surrounding tissues through the basement membrane beneath the skin or mucosa. Precancerous lesions can develop into carcinoma in situ, which, if untreated, can further develop into invasive cancer. Carcinoma in situ is the earliest stage of cancer, also known as stage 0 cancer, and can be completely cured by surgical resection at this stage. Carcinoma in situ is commonly found in the cervix, skin, bronchus, stomach, prostate, and breast.