Floor of the Mouth Cancer

The floor of the mouth (floor of the oral cavity) is the soft tissue that lies beneath the tongue and extends in a horseshoe shape between the inner surface of the lower jawbone and the tongue. Cancer developing from the thin lining tissue of this area is called floor of the mouth cancer. Because it lies beneath the tongue it can be overlooked; nevertheless, it is easily seen on a careful examination of the mouth.

What is floor of the mouth cancer?

The floor of the mouth is covered by a thin, mobile lining layer (mucosa); directly beneath it lie the structures that attach the tongue to its muscles, the sublingual salivary glands and the ducts of the submandibular salivary glands. The great majority of cancers arising from this tissue are squamous cell cancers (squamous cell carcinoma). Because the distance between the floor of the mouth, the lower jawbone (mandible) and the tongue is short, the tumour may advance into these neighbouring structures as it grows. Owing to the rich lymphatic network of the area, the tendency to spread to the lymph nodes (lymph glands) in the neck is also taken into account.

Cigarettes and other tobacco products and alcohol use are the most important risk factors; using the two together raises the risk further. Poor oral hygiene and constant irritation may also contribute.

Symptoms

• A sore or ulcer beneath the tongue that does not heal
• A white (leukoplakia) or red (erythroplakia) patch on the floor of the mouth
• A palpable firm area or thickening beneath the tongue
• Difficulty moving the tongue, a change in speech
• Pain; sometimes pain radiating to the ear
• Loosening of the lower front teeth, dentures that no longer fit
• Swelling beneath the jaw or in the neck

There may be no pain in the early period; for this reason a painless firm area or patch should also be taken seriously.

Diagnosis

On examination the floor of the mouth is assessed both by eye and by hand; examination with both hands (bimanual palpation) gives an idea of the depth of the tumour. For a definitive diagnosis a tissue sample (biopsy) is taken from the suspicious area. To see the tumour’s closeness to the lower jawbone and the state of the neck lymph nodes, computed tomography (CT), magnetic resonance imaging (MRI) or ultrasonography is used. With these findings the stage of the disease (stage I–IV) is determined.

Treatment

The main treatment for floor of the mouth cancer is surgery. The tumour is removed together with a margin of healthy tissue around it. While small tumours can be removed through the mouth, in tumours close to or advancing into the bone, part of the lower jawbone may also need to be removed. Because the salivary ducts pass through this area, re-routing these ducts or removing the submandibular gland may come into consideration during the operation.

The neck lymph nodes are removed in the same operation according to the likelihood of spread (neck dissection). If the tissue loss is large, reconstruction with tissue taken from another part of the body is performed to preserve the movement of the tongue. Depending on the pathology result, radiation therapy (radiotherapy) may be added.

What to expect after surgery

Because the floor of the mouth is directly related to the movement of the tongue, temporary difficulty with speech and swallowing may be experienced after surgery. As the swelling subsides and the tissue heals, these functions improve over time; swallowing and speech therapy is used when needed. Careful maintenance of oral hygiene supports healing.

When should you see a doctor?

If you notice a sore, firm area or patch beneath your tongue that has not gone away for several weeks, you are advised to see an ear, nose and throat specialist even if there is no pain.