Don’t Brush Off a Mouth Ulcer: This Type of “Canker Sore” Could Be a Cancer Warning

Most people have had that moment: you bite into a steamed bun in the morning and a mouth ulcer sends a sharp jolt through your mouth. Even a breath of cool air makes you wince. Most people treat a canker sore as a minor “internal heat” problem. But did you know that one kind of ulcer can be an early scout for oral cancer? Today, let’s look at the dangerous signals inside the mouth and stop cancer while it is still in the bud.

Ordinary ulcers and cancerous ulcers can be surprisingly easy to confuse. Oral cancer is a common malignant tumor of the head and neck, mainly occurring in the oral mucosal tissue. Clinically, it can be divided into lip cancer, tongue cancer, buccal mucosa cancer, gum cancer, floor-of-mouth cancer, and other types. More than 90% are squamous cell carcinoma.

An ordinary ulcer is like an impatient guest. It usually heals on its own in one to two weeks. Its signature is the “yellow, red, hollow, painful” quartet: a yellow-white pseudomembrane on the surface, red and swollen surrounding tissue, a sunken center, and obvious pain, but it is self-limiting. A cancerous ulcer is more like a stubborn squatter. It stays for more than two weeks and comes with the “long-lasting, hard, everted” features: the ulcer does not heal, the base feels hard or lumpy, and the edges are raised and everted like a volcano crater. It may also come with local numbness or abnormal sensation.

The key point: if an ulcer has not healed after two weeks, especially if it feels hard or has rolled edges, go to an oral and maxillofacial surgery department for an examination as soon as possible.

Besides an ulcer that will not heal, there are four warning signs of oral cancer to watch for. The first is strange changes in mucosal color. Leukoplakia appears as white patches in the mouth that cannot be wiped off and feel rough, like sandpaper. Erythroplakia is a red alert that is even more dangerous than leukoplakia: bright red patches that bleed when touched and have a very high rate of malignant transformation. Mixed patches, with white and red areas appearing together, significantly increase cancer risk.

The second is hard lumps. You may feel a painless hard lump in the mouth, such as on the side of the tongue, the cheek, or the gums, hard like a small stone. Swollen lymph nodes in the neck, especially near the angle of the jaw, that are painless and fixed may mean lymph node metastasis has already occurred.

The third is a mouth that will not cooperate. The tongue becomes less flexible, speech becomes unclear, and swallowing food becomes difficult. You may be unable to open your mouth wide, so even eating an apple requires small bites; cancer cells may be causing trouble. Teeth may suddenly become loose. Do not assume it is just periodontitis; it could be gum cancer causing damage.

The fourth is unexplained bleeding and bad breath. The ulcer surface may seep blood for no reason and still bleed after rinsing. Local numbness or pain can occur when a cancer invades nerves, such as the inferior alveolar nerve and lingual nerve, causing numbness of the lower lip on the same side, stinging of the tongue, or radiating ear pain. There may also be a persistent foul smell in the mouth, like rotten apples, which may be caused by tumor necrosis.

Three dangerous combinations are especially cancer-causing. Smoking, including secondhand smoke, feeds carcinogens directly to the mouth. Smokers have a 5 to 25 times higher risk of oral cancer than non-smokers. Burning tobacco releases more than 70 carcinogens, which damage the oral mucosa like poison, while the high heat of the smoke repeatedly “burns” oral tissue.

Drinking alcohol opens the door for carcinogens. Drinking three liang of baijiu, about 150 ml, every day increases the risk of oral cancer by 3 to 9 times. Acetaldehyde produced when alcohol is metabolized is a strong carcinogen, and alcohol also makes it easier for toxins in tobacco to penetrate the mucosa.

Chewing betel nut damages the mouth in two ways, soft and hard. Betel nut is internationally recognized as a carcinogen, and people who chew it have 28 times the risk of oral cancer compared with other people. Areca alkaloids stimulate cancerous changes in the mucosa, while coarse fibers rub the mouth repeatedly like steel wool, triggering chronic ulcers.

High-risk warning: betel nut plus smoking plus alcohol can increase the risk 123-fold. It is like giving cancer cells a fast track. Other risk factors include HPV infection, especially HPV16; chronic oral irritation; and ultraviolet exposure.

Four things can help prevent cancer. First, eat the right foods to put armor on your mouth. The antioxidant big three are 100 g of broccoli, 300 ml of green tea, and one tomato every day, to clear out harmful molecules in the body. A vitamin A, C, and E combination, such as carrots, kiwi fruit, and almonds as snacks, can strengthen mucosal resistance. Whole grains such as oats and brown rice help bind carcinogens in the gut so they can be excreted. Mushrooms, including lentinan from shiitake mushrooms, help enhance immunity. Selenium, from two Brazil nuts a day, enhances glutathione peroxidase activity. Zinc, from oysters twice a week, promotes mucosal repair and helps maintain taste function. What to avoid: let hot soup and milk tea cool below 60°C before drinking, and eat less ham, cured meat, and the burnt parts of barbecue.

Second, take care of oral hygiene with a daily cleanup. Brush your teeth twice a day and use dental floss to remove food debris between teeth. Get professional dental cleaning one to two times a year, and have a dental examination every six months, focusing on the sides of the tongue and the floor of the mouth. Remove broken tooth roots that rub the mouth, and replace dentures with sharp edges so they do not repeatedly irritate the mouth.

Third, stay away from dangerous behaviors. Refuse betel nut for life. Quit smoking and limit alcohol; if you cannot quit completely, reduce the amount gradually. Protect against HPV infection. In summer, wear a wide-brimmed hat and use lip balm with SPF so ultraviolet rays do not cause lip cancer.

One last reminder: 80% of oral cancers are preventable. Make regular self-checks a habit. Open your mouth in front of a mirror and look for abnormal ulcers or hard lumps, and feel your neck for swollen bumps. Protecting oral health starts with paying attention to every “small ulcer.”