Treatments: Submandibular Gland Tumors

The big picture: why the plan depends on what the lump turns out to be

The single most important fact about submandibular gland tumors is that, compared with the larger parotid gland in front of the ear, a much higher share of true tumors here are cancerous — roughly 40 to 50 percent, versus about 20 percent in the parotid. Because of that, the surgeon generally cannot simply "shell out" a submandibular lump and watch it. The usual approach is to remove the whole gland together with the tumor in one piece, both to cure benign tumors reliably and because a benign-looking lump sometimes proves cancerous only after it is examined under the microscope.

A second fact shapes every operation here: three important nerves run right next to the gland. Protecting them is the surgeon's central task. They are:

• The marginal mandibular branch of the facial nerve, which lifts the lower lip and corner of the mouth (injury causes a crooked smile).
• The lingual nerve, which carries sensation and taste to one side of the tongue.
• The hypoglossal nerve, which moves the tongue.

With that background, here is how treatment is approached for each kind of tumor, in the same order as the companion conditions guide.

Surgery: the foundation of treatment

For almost every submandibular tumor that is not a lymphoma, surgery is the first and most important step.

Removing the gland. The standard operation is complete removal of the submandibular gland along with the tumor (total gland excision). It is usually done through a small incision in a natural skin crease of the upper neck, placed two to three-and-a-half centimeters below the jawbone to keep it away from the lip nerve. Simply scooping the tumor out of the gland ("enucleation") is avoided because it leaves tumor behind and leads to high recurrence rates.

Protecting the three nerves. Surgeons use well-established maneuvers to keep the nerves safe — for example, tying off and lifting the facial blood vessels to carry the lip nerve up and out of the way (the "Hayes-Martin maneuver"), and deliberately identifying the lingual and hypoglossal nerves before removing the gland. A nerve stimulator may be used to help locate and monitor nerves during the operation.

When more than the gland must come out. For cancers, the surgeon removes a margin of surrounding healthy tissue, and for larger or more aggressive tumors may need to take nearby muscle, part of the jawbone, or other involved structures to be sure all the cancer is removed. If a tumor has actually grown into one of the nerves, that nerve segment may have to be removed; when possible, it can sometimes be repaired with a nerve graft.

Removing lymph nodes (neck dissection). The gland sits in the first "station" of neck lymph nodes (level I). For cancers, the surgeon often removes neck lymph nodes to check for and clear any spread. At a minimum, the nodes immediately around the gland are taken; for high-grade or larger cancers, or when nodes are already known to be involved, a more extensive neck dissection is done. Benign tumors do not require node removal.

Possible side effects of surgery. Most people recover well, but the realistic risks include:

• Weakness of the lower lip on the operated side (a crooked smile) from stretching or injury of the marginal mandibular nerve — usually temporary (around 7 percent for benign tumors), rarely permanent (under about 1 percent).
• Numbness or altered taste on one side of the tongue (lingual nerve) — uncommon, and permanent in only a small percentage.
• Weakness or altered movement of the tongue (hypoglossal nerve) — rare.
• A collection of blood (hematoma), infection, a scar, a saliva leak, and some hollowing of the contour under the jaw where the gland used to be.
• Some dry-mouth effect: because the submandibular glands make much of the saliva you produce at rest, removing one gland can cause a modest dry-mouth sensation, though the remaining glands usually compensate.

A newer, gland-sparing option. For tumors that are confidently benign before surgery, some centers now offer a more limited operation that preserves part of the gland. Studies so far show similar low recurrence with less nerve risk, better saliva flow, and a better cosmetic result — but follow-up is still relatively short, and many surgeons still prefer complete gland removal as the safer default, especially when the diagnosis is not certain beforehand.

Treatment of benign tumors

Pleomorphic adenoma is by far the most common benign submandibular tumor, and the treatment is surgical removal of the gland with the tumor. Even though it is not cancer, three features make complete removal the standard rather than watchful waiting:

• Its capsule is often incomplete, with tiny finger-like projections, so scooping it out leaves microscopic tumor behind and leads to recurrence in a large share of cases, versus only a few percent after proper removal.
• When it does recur, it tends to come back in multiple nodules that are harder to remove and put the nearby nerves at greater risk.
• Over many years, a small but real fraction of these tumors can turn into a cancer (carcinoma ex pleomorphic adenoma) — roughly 1.5 percent within the first five years, rising substantially if left untreated for well over a decade.

For these reasons, timely surgery is recommended rather than long-term observation. Follow-up continues for years afterward, because recurrences can appear a decade or more later.

Treatment of submandibular cancers

The general framework is surgery first, radiation afterward in higher-risk cases, and medication (systemic therapy) reserved for advanced, recurrent, or spread disease.

Surgery (removal of the gland and tumor, with neck lymph nodes as described above) is the cornerstone for cancer that can be removed.

Radiation therapy after surgery is added when the pathology shows features that raise the risk of the cancer coming back. These include high-grade tumors, cancer cells at or near the cut edge (positive or close margins), invasion of nerves, spread to lymph nodes, invasion of lymphatic or blood vessels, and larger (T3–T4) tumors. One tumor type deserves special mention: adenoid cystic carcinoma, the most common submandibular cancer, has a strong tendency to creep along nerves, so radiation after surgery is recommended for essentially all of these tumors regardless of stage. Radiation is typically given as a precise, computer-shaped beam (intensity-modulated radiation therapy) over several weeks; specialized proton or other particle-beam radiation is available at select centers for difficult cases.

Adding chemotherapy to radiation is not a routine practice for salivary gland cancers. Unlike some other head and neck cancers, the available evidence has not shown that combining chemotherapy with post-surgery radiation improves survival, so major guidelines advise against doing so routinely. A large clinical trial (RTOG 1008) was designed to answer this question directly, with results anticipated soon.

Medication for advanced or spread cancer. When a submandibular cancer cannot be removed, comes back, or spreads to distant sites, treatment increasingly depends on testing the tumor for specific molecular targets, which can unlock targeted drugs:

• Tumors driven by the androgen receptor (common in salivary duct carcinoma) may respond to hormone-blocking therapy similar to that used in prostate cancer.
• Tumors that overexpress HER2 may respond to HER2-directed drugs such as trastuzumab-based treatment.
• The rare secretory carcinoma, which carries an NTRK gene fusion, can respond dramatically to NTRK-blocking pills (larotrectinib, entrectinib, or repotrectinib), with the majority of tumors shrinking.

Standard chemotherapy can also be used, though response rates are modest, and immunotherapy (checkpoint inhibitors) has limited benefit in most salivary cancers except for tumors with specific markers. For slow-growing spread — particularly the quiet lung metastases that adenoid cystic carcinoma can produce — careful observation is sometimes the wisest initial choice.

Treatment of cancer that has spread to the submandibular area

As the conditions guide explains, true spread of a distant cancer into the submandibular gland itself is uncommon; far more often it is the lymph nodes beside the gland that are involved by a skin cancer of the face or scalp.

Skin squamous cell carcinoma that has spread to these nodes is generally treated with surgery to remove the involved nodes plus the primary skin cancer, followed by radiation when there are multiple involved nodes, a large node, or spread of cancer outside the node capsule. For disease that cannot be removed or has spread widely, immunotherapy drugs (cemiplimab or pembrolizumab) are the preferred medications.

Melanoma that has spread to these nodes is treated with surgery, now increasingly paired with immunotherapy given before and/or after the operation; recent trials favor starting immunotherapy before surgery for node disease that can be felt or seen on scans. For melanomas with a BRAF mutation, targeted pills are an alternative.

Treatment of lymphoma

Lymphoma is a cancer of the immune system's cells, and it is treated very differently from the other tumors in this guide — by blood-cancer specialists (hematologists/oncologists) rather than primarily by surgery. Surgery's role is usually just to obtain the tissue needed for diagnosis.

• The most common type here is an indolent (slow-growing) MALT lymphoma. When it is confined to the gland, a low dose of focused radiation is the preferred treatment and controls the disease in the large majority of patients. When it is more widespread, a rituximab-based medication regimen is used instead. In people with Sjögren syndrome, doctors sometimes favor medication over radiation to avoid worsening dry mouth.
• The more aggressive diffuse large B-cell lymphoma is treated with a standard immunochemotherapy combination known as R-CHOP, the same regimen used for this lymphoma elsewhere in the body, which cures the majority of patients.

Questions worth asking your care team

• Based on my biopsy and scans, is my tumor most likely benign or cancerous, and how confident can we be before surgery?
• What exactly will be removed, and which nerves are at risk in my case?
• What are my personal chances of temporary versus permanent lip weakness, tongue numbness, or tongue-movement problems?
• Will I need lymph nodes removed, and why?
• After surgery, how will we decide whether I need radiation?
• If this is a cancer, will the tumor be tested for molecular targets that could guide drug therapy?
• If this turns out to be a lymphoma, which specialist will coordinate my care?