Sores That Don't Heal: A Possible Cancer Sign

Most cuts, scrapes, and sores heal within a couple of weeks. A sore that does not heal, or keeps coming back in the same spot, is worth checking. It can be an early sign of skin cancer or a cancer of the mouth or throat.

A sore on the skin, lip, or in the mouth that has not healed after about three to four weeks is the pattern doctors want to see. This includes a sore that scabs over and then reopens repeatedly, or one that looks the same or gets worse instead of fading. A sore that bleeds easily with little contact is another detail worth mentioning.

On the skin, a sore that will not heal can be a sign of basal cell or squamous cell skin cancer, or melanoma. These cancers can look like a pimple, scab, or scaly patch that never fully goes away. In the mouth, a sore on the lip, tongue, gums, or the lining of the cheek that lasts more than a few weeks can be a sign of oral cancer. Risk is higher for people who use tobacco or drink alcohol heavily.

Cold sores, canker sores, and minor injuries from biting your cheek or a rough tooth explain most mouth sores, and these usually heal within one to two weeks. On the skin, eczema, minor infections, and slow-healing scrapes are common, especially in people with diabetes or poor circulation, where healing naturally takes longer. Most sores, even ones that take a while, are not cancer.

Your doctor examines the sore's size, shape, color, and how it has changed over time. They ask how long it has been there and whether it comes and goes or has been continuously present. For a skin sore, a biopsy is often the most reliable next step: removing a small piece of the sore, or the whole thing, to check under a microscope. For a mouth sore, the doctor looks at the area first, sometimes with a light or a small mirror. A biopsy follows if anything looks odd. The slides take several days to prepare. The National Cancer Institute says the report usually reaches your doctor within 10 days.

A visual exam alone cannot always tell a harmless sore from an early cancer, which is why a biopsy matters for anything that does not heal on schedule. If a sore persists past the expected healing time despite treatment, a biopsy is the more reliable way to settle the question.

• Call 911 or go to an emergency department if a sore bleeds and will not stop with steady pressure, or a mouth or throat sore is making it hard to breathe or swallow your own saliva.
• Call your care team or dentist the same day if the sore is spreading quickly, or the area around it is hot, swollen, and painful with a temperature of 100.4°F (38°C) or higher.
• Call your care team or dentist within a day or two if a sore on the skin, lip, or inside the mouth has gone three to four weeks without healing, keeps reopening in the same spot, or now sits beside a lump or a patch of numbness.

• This sore has not healed in [how long] — should it be biopsied?
• Could this be a cold sore, canker sore, or minor injury?
• Am I at higher risk given my sun exposure, smoking, or drinking history?
• How should I watch it if we decide to wait?

• American Cancer Society — Signs and Symptoms of Cancer
• American Cancer Society — Signs and Symptoms of Oral Cavity and Oropharyngeal Cancer
• National Cancer Institute — Pathology Reports