Having a sore in your mouth is no fun. They're easily irritated — and downright painful at those times.
Is it a mouth ulcer? They're certainly very common, and usually not something in need of a doctor's evaluation. A harmless annoyance that you just have to wait to clear up over the next week or two.
But what about a sore that doesn't seem to get better, that persists for weeks, even months. Or one that keeps getting bigger, more painful or starts to bleed?
Could it be mouth cancer?
"Early detection is the key to earlier treatment and improved outcomes for oral cancers. " says Dr. Stephanie Chen, head and neck surgical oncologist at Houston Methodist.
It's why cancer experts stress that a mouth sore that won't go away should be evaluated sooner rather than later.
Still, there are some questions you might want answered first. Are you even at risk for mouth cancer? How long is too long for a sore to last in your mouth? What does mouth cancer look like — specifically, how can you tell a harmless mouth ulcer from cancer?
Dr. Chen answers these questions and more.
What causes mouth cancer?
Similar to other types of cancer, mouth cancer — also called oral cancer — happens when mutations accumulate and cause cells to grow out of control. In the case of mouth cancer, this happens most commonly in the thin, flat mucosal cells that line the inside of your mouth.
Anyone can develop mouth cancer, but certain factors increase a person's risk:
- Smoking or chewing tobacco
- Heavy alcohol use
- Gum disease (periodontitis)
"Tobacco use of any kind, including smoking cigarettes, cigars, and chewing tobacco, is historically one of the strongest risk factors for oral cancers," says Dr. Chen. "A combination of tobacco and heavy alcohol use can further increase the risk for oral cancer. However, there are other risk factors including autoimmune conditions, significant sun exposure, and poor dental health."
This explains why mouth cancer can occur in people who have never smoked a cigarette in their life. In these cases, gum disease is often the culprit.
"The chronic inflammation that happens around the teeth with gum disease is another common reason we see this type of cancer develop," adds Dr. Chen.
Dr. Chen says that while long-term effects of vaping are still being investigated, there are increasing studies that suggest vaping also increases the risk for oral cancers.
"While there are fewer carcinogens in e-cigarettes compared to traditional cigarettes, the nicotine exposure and inflammation caused by vaping can result in DNA damage and gum disease, increasing the risk for oral cancers to develop. Switching from cigarettes to vaping can be a good first step to improve health, but ultimately complete tobacco cessation is necessary to significantly reduce the risk of developing cancer," adds Dr. Chen.
What are the signs of mouth cancer?
"There are two basic ways that oral cancers present in the mouth — as white patches or red patches," says Dr. Chen. "Red patches are a bit more concerning than white patches, but either needs to be evaluated if it doesn't go away after several weeks."
These patches can occur anywhere inside of your mouth, including:
- Inside the upper and lower lip
- Inside the cheeks
- Around the gum line and teeth
- Underneath the tongue
- On the tongue itself
- On the roof of the mouth
- At the back of the mouth (behind the molars)
Dr. Chen says it's unclear why red patches are more concerning than white ones.
"There's a lot of speculation about what's going on at the cellular level to make red patches more concerning, but no defined answer yet," Dr. Chen explains. "What we do know is that red patches have a higher likelihood of being cancerous or precancerous."
Mouth ulcer vs. cancer: What's the difference?
Mouth ulcers can look like red or white patches, too. So how can you tell if what you're seeing is really a harmless ulcer or a sore that needs evaluating?
"One major difference is that a mouth ulcer will come and go within one to two weeks," says Dr. Chen. "Oral cancer won't. Any patch in the mouth that lingers beyond four to six weeks needs to be evaluated."
Other mouth cancer symptoms that can help differentiate it from an ulcer include changes to the patch, such as:
- Pain
- Spontaneous bleeding
- Progressive growth
- Thickening
"If the patch is changing or growing, that's a sign that it may not be benign and could be progressing into cancer," Dr. Chen points out.
Additionally, she says that unexplained bleeding is always a red flag for something more serious.
"Bleeding can happen if you bite an area in your mouth where a sore has developed, but a mouth ulcer typically won't bleed on its own spontaneously," explains Dr. Chen. "Whereas deeper infiltrating precancers and cancers of the mouth can have spontaneous bleeding."
What should you do if you have a mouth sore that won't go away?
Anytime you have a sore, ulcer or painful patch in your mouth that won't go away, Dr. Chen says it's important to be evaluated by an ENT specialist, a doctor who specializes in the ear, nose, and throat.
"Often times, these patches are noticed by dentists who then refer the person to an ENT doctor," says Dr. Chen. "But if you notice a persistent issue between dental visits, don't wait to schedule an appointment with an ENT doctor to have it checked."
During the evaluation, your doctor will perform a visual exam and ask you about your risk factors.
"When there is a high enough level of concern based on the lesion's appearance and the person's risk factors, we proceed by performing a tissue biopsy," explains Dr. Chen. "For example, if someone with poor dental health develops a rapidly growing lesion inside their mouth, that's much more worrisome than someone with a sore that looks concerning but who has impeccable dental hygiene."
Mouth tissue biopsy is a standard, straightforward procedure that can be performed safely and comfortably in your doctor's office — even at the first visit if the concern is great enough.
"We administer numbing spray and a numbing injection," explains Dr. Chen. "Then we biopsy the site. At times, a limited number of stitches may be needed."
If biopsy results indicate cancer, treatment varies based on how advanced the cancer is.
"With any mouth cancer, full surgical removal is the primary mode of treatment," says Dr. Chen. "Depending on cancer staging, additional therapies, like radiation or chemotherapy, may be needed. Ideally we find the cancer early enough to avoid having to use these additional therapies, which is another reason we stress having suspicious lesions evaluated as soon as they're noticed."
