The Ten Most Common Types of Precancerous Lesions

A precancerous lesion refers to certain benign lesions or conditions that carry the potential to become malignant; if left to persist over a long period, they may progress into malignant tumors. It should be noted, however, that a precancerous lesion does not inevitably develop into cancer. Patients with such conditions should take steps to prevent malignant transformation, but there is no need to endure excessive psychological stress over it.

This article introduces the ten most common categories of precancerous lesions.

• Breast proliferative fibrocystic disease

Breast proliferative fibrocystic lesion is a benign proliferative condition of the breast tissue, commonly referred to as fibrocystic breast disease. It is most often seen in women of reproductive age between 30 and 50 years old, and its cause is closely related to an imbalance of female estrogen and progesterone. Long-term endocrine disruption in women leads to dilation of breast ducts, epithelial proliferation, or cystic changes.

This condition usually does not significantly affect the patient’s daily life and requires no special treatment, but it is important to be aware that it carries a risk of malignant transformation. Patients should therefore undergo regular follow-up examinations. They should also avoid unhealthy lifestyle factors such as excessive mental stress, irregular sleep-wake schedules, and high-fat diets, all of which are high-risk factors that promote the malignant transformation of breast proliferative fibrocystic disease.

It should be noted that when cystic dilation of breast ducts and proliferation of lobular and ductal epithelial cells are accompanied by atypical ductal epithelial hyperplasia, the probability of malignant transformation increases markedly. Such patients are at high risk of developing invasive breast cancer. When necessary, the affected tissue can be resected in advance to prevent cancerous change.

• Pulmonary squamous epithelial dysplasia and pulmonary atypical adenomatous hyperplasia

Pulmonary squamous epithelial dysplasia and atypical adenomatous hyperplasia are the precancerous lesions of lung squamous cell carcinoma and lung adenocarcinoma, respectively.

Squamous epithelial dysplasia (also called squamous metaplasia) is mostly associated with smoking or chronic inflammation of the respiratory tract. It presents as abnormal proliferation of squamous epithelial cells in the bronchial mucosa. The epithelial tissue of the bronchial mucosa is normally pseudostratified ciliated columnar epithelium, but long-term irritation from smoking or chronic inflammation causes the bronchial mucosa to develop squamous epithelium (stratified squamous epithelium). Over time, this may progress to lung squamous cell carcinoma.

Atypical adenomatous hyperplasia presents as abnormal proliferation of alveolar wall epithelial cells, usually ≤5 mm. Imaging findings most often show ground-glass nodules, commonly located in the peripheral regions of the lung.

Approximately 10%–30% of patients with atypical adenomatous hyperplasia may progress to adenocarcinoma in situ. Therefore, when a ground-glass nodule is found on a routine physical examination, regular follow-up is necessary. Once the nodule becomes an intermediate- or high-risk nodule, surgical resection can be performed to prevent cancerous change.

• Colorectal adenoma or chronic ulcerative colitis

A colorectal adenoma is a benign tumor arising from the glandular epithelium of the colorectal mucosa and is a precancerous lesion of colorectal cancer. Most patients have no obvious symptoms in the early stage, and detection relies on colonoscopy. Timely intervention can effectively reduce the risk of malignant transformation. Treatment is mainly endoscopic resection or surgery, with regular follow-up after the procedure.

Colorectal adenomas may be single or multiple and include types such as villous adenoma and tubular adenoma; both carry the potential for malignant transformation, with villous adenomas carrying a higher cancer risk. The larger the adenoma diameter (over 1 cm) and the greater the villous component, the higher the cancer risk.

The malignant transformation rate of familial adenomatous polyposis is 100%. Once familial adenomatous polyps are diagnosed, surgical resection should be performed as early as possible, with regular follow-up.

Chronic ulcerative colitis is an inflammatory bowel disease. Its recurrent episodes lead to intestinal mucosal ulceration and hyperplasia, which may further progress to colorectal adenocarcinoma.

• Helicobacter pylori infection, chronic atrophic gastritis with epithelial metaplasia, and gastric ulcer

Helicobacter pylori infection, chronic atrophic gastritis with epithelial metaplasia, and gastric ulcer are the three most common precancerous lesions of gastric cancer. When all three, or any two, occur together, the probability of malignant transformation is even higher.

H. pylori infection can be diagnosed by the carbon-13 or carbon-14 urea breath test or by gastroscopy. H. pylori infection can be eradicated with quadruple or triple therapy.

• Chronic skin ulcers or pigmented moles in frequently friction areas

The most common skin cancers are cutaneous squamous cell carcinoma and melanoma. The precancerous lesions of these two cancers are the easiest for patients or their families to notice, because changes in the skin can be observed with the naked eye.

Long-unhealed skin ulcers and fistulas, due to persistent irritation, cause repeated proliferation of the surrounding squamous epithelium. Over time, atypical hyperplasia appears, which may further progress to cutaneous squamous cell carcinoma.

Pigmented nevi in areas subject to frequent friction, because of continuous stimulation, are also prone to atypical hyperplasia and may further develop into malignant melanoma. Malignant melanoma commonly occurs on the palms, soles, and vulva (areas easily subjected to friction), and may also appear on the trunk or extremities. It may develop from a pre-existing mole or arise as a new lesion.

Early warning signs of malignant melanoma on the body surface typically include: 1. Uneven color of a skin mole, with areas of varying darkness within the same mole, or reddish or whitish patches; 2. Blurred edges of the mole to the naked eye, with the previously sharp border becoming irregular or serrated; 3. Rapid enlargement, exceeding 6 mm in diameter or increasing noticeably over a short period; 4. Accompanying symptoms such as itching, pain, ulceration, oozing, or redness and swelling of the surrounding skin.

Whether a skin ulcer or abnormal changes in a mole, these are all early signals of malignant transformation. For tumors on the body surface, once detected, most can be eradicated with a simple outpatient surgical procedure. Such treatment is minimally invasive, has a quick recovery, is low in cost, and offers great benefit.

• Hepatitis B or liver cirrhosis

Hepatitis B is an infectious hepatitis, usually chronic. Hepatitis B is the most important precancerous lesion of liver cancer. Both hepatitis B virus carriers and patients with hepatitis B may progress to liver cancer. China has a large hepatitis B burden; statistics show that there are currently about 100 million hepatitis B virus carriers and patients in China, and approximately 400,000–500,000 new liver cancer cases are added each year, accounting for about 40%–50% of the global total. China has the highest liver cancer incidence rate in the world.

Both hepatitis B virus carriers and hepatitis B patients should regularly monitor HBV viral load, liver function, alpha-fetoprotein, and carcinoembryonic antigen. Once abnormalities appear, corresponding treatment should be initiated immediately.

Liver cirrhosis is mostly caused by chronic liver injury; common etiologies include hepatitis, schistosomiasis, and alcohol abuse. When the liver is injured, it attempts to repair itself, but during this repair process it erroneously grows large amounts of scar tissue.

This scar tissue is composed of fibroblasts, inflammatory cells, and capillaries. Over time, the scar tissue gradually replaces normal liver tissue, causing the liver to harden with an uneven, nodular surface—hence the name cirrhosis.

Advanced cirrhosis leads to serious complications such as ascites and portal hypertension, which can cause death. Long-standing cirrhosis also leads to malignant transformation of the liver. Cirrhosis combined with liver cancer is very difficult to treat, but early detection gives a much better prognosis.

• HPV infection with cervical atypia

Human papillomavirus (HPV) infection with cervical epithelial atypia is a precancerous lesion of cervical cancer. The best way to prevent such lesions is HPV vaccination. Even if someone has already been infected with HPV, vaccination is still recommended. Although the HPV vaccine cannot treat an existing HPV infection, HPV is a large family of viruses, and vaccination can still prevent infection by other HPV types.

Those already infected with HPV should undergo regular follow-up; the main screening test is TCT (liquid-based thin-layer cytology). Those not infected, or unsure of their status, can choose combined HPV and TCT cervical cancer screening.

• EBV infection with nasopharyngeal mucosal dysplasia

Epstein-Barr virus (EBV) infection with nasopharyngeal mucosal dysplasia is a precancerous lesion of nasopharyngeal carcinoma. EBV belongs to the lymphocryptovirus genus of the herpesvirus family (a type that specifically attacks lymphocytes) and is structurally a double-stranded DNA pathogen. EBV is mainly transmitted through close contact via saliva; sharing eating utensils and kissing can both spread EBV, which is why EBV infection often clusters within families.

EBV infection can lead to various malignancies, including nasopharyngeal carcinoma and lymphoma. When EBV infection is accompanied by nasopharyngeal mucosal dysplasia, the risk of malignant transformation into nasopharyngeal carcinoma rises significantly. In such cases, regular follow-up is necessary; if the condition progresses, the affected area can be surgically removed in advance.

• Oral/genital leukoplakia

Leukoplakia is a lesion that commonly occurs on the mucous membranes of the esophagus, oral cavity, uterine cervix, and vulva. It is mostly caused by excessive proliferation and keratinization of the squamous epithelium; to the naked eye it appears as white plaques. If leukoplakia fails to heal over a long period, it may progress to squamous cell carcinoma.

• Recurrent gallstones, solitary gallbladder polyps, or cholecystitis with atypia

Recurrent gallstones, solitary gallbladder polyps (especially those larger than 1 cm in diameter), and cholecystitis with atypical hyperplasia are precancerous lesions of gallbladder cancer and cholangiocarcinoma. These conditions are often related to poor dietary habits, such as long-term skipping of breakfast, a preference for spicy and greasy foods, and heavy alcohol consumption. These factors irritate the biliary system, causing biliary obstruction and bile stasis; over time they lead to gallstones, cholecystitis, and gallbladder polyps. Chronic cholecystitis, gallstones, and multiple gallbladder polyps left untreated or failing to heal over time carry the potential for malignant transformation.

In the early stages of biliary tract disease, patients are usually asymptomatic. As the condition progresses over time, symptoms such as dull upper abdominal pain and distension gradually appear; acute episodes may present as severe biliary colic accompanied by jaundice.

A balanced and regular diet can reduce the incidence of chronic biliary tract disease. If a solitary gallbladder polyp larger than 1 cm is found, surgical removal should be considered.

Cancer is not an acute disease. Most cancers do not arise from the sudden malignant transformation of our tissues and organs. It takes a long time to progress from a precancerous lesion to cancer. If we learn more about cancer in our daily lives and take appropriate measures at the precancerous stage, we can prevent cancer from developing or detect it early.

Cancer is both preventable and treatable. Cancers detected at the carcinoma in situ stage have a cure rate approaching 100% after surgical treatment. Early-stage cancers also have a cure rate of over 90% after surgery. If we are careless and the cancer is not detected until the middle or advanced stages, the cure rate drops dramatically.