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Minor salivary gland tumor
— Minor salivary gland tumors arising within the oral cavity may present
as a painless submucosal mass in the palate, lips, or buccal mucosa. They
may be ulcerated and must be distinguished from sialometaplasia or
squamous cell carcinoma. When they present in the nasal cavity or
maxillary sinus, these tumors can produce nasal obstruction, congestion,
vision changes, or trismus. Minor salivary gland tumors involving the
nasopharynx usually present at an advanced stage, often with invasion of
the skull base, intracranial extension, and involvement of cranial nerves. PRIMARY TREATMENT — The treatment and outcome of salivary gland tumors (SGTs) depends upon whether the tumor is benign or malignant, and if malignant, the primary site.
Minor salivary glands — The surgical
treatment of minor salivary gland neoplasms depends on location and
histologic grade. Surgical resection should include an adequate cuff of
normal tissue. Involvement of bone (mandible or maxilla) requires an
appropriate palatectomy or mandibulectomy. For high-grade or larger ( Elective node dissection is indicated for salivary gland malignancies arising in the nasopharynx regardless of size or grade. In one series of 23 such patients treated with combined surgery and RT, occult cervical node metastases were detected in 7 of 15 patients (47 percent) who underwent surgery prior to RT. Despite this adverse finding, five-year local control rates were 77 percent, and disease-specific survival rates at 5 and 10 years were 67 and 48 percent, respectively. Adjuvant RT should be considered for all patients presenting with a nasopharyngeal minor salivary gland malignancy. Adjuvant RT — There is a general consensus that patients with low-grade T1 and T2 primaries can be adequately treated by surgery alone, with the exception of nasopharyngeal minor salivary gland cancers (see above) and adenoid cystic cancers (see below). Postoperative RT is recommended for larger or more invasive malignant tumors (most T3/4 lesions), and for malignant salivary gland neoplasms in the following circumstances
Because of the unique affinity of adenoid cystic carcinoma for neural involvement, many authors recommend routine postoperative RT regardless of stage or margin status, although this is somewhat controversial. Guidelines from the National Comprehensive Cancer Network (NCCN) recommend RT for all adenoid cystic tumors, although there is nonuniform agreement on this recommendation for T1 tumors. In contrast, others suggest reserving postoperative RT for patients with adenoid cystic cancer who have advanced T stage (T3/4) or positive resection margins Multiple retrospective reports suggest better local control when RT is added to surgery, but the impact on survival is uncertain. There are no randomized trials comparing surgery alone or with RT, but several observational series have compared outcomes among patients treated with and without RT. In most cases, RT has been added because of the presence of adverse features. Minor salivary gland cancer — As noted previously, minor salivary gland cancers tend to have a worse outcome than those involving the major salivary glands, particularly adenoid cystic cancers. In an early report of 434 malignant minor salivary gland tumors from Memorial Sloan Kettering, the cause-specific 5-, 10-, and 15-year survival rates were 44, 32, and 21 percent, respectively A second retrospective series from this same group suggested better outcomes over time. The 5-, 10-, and 15-year survival rates for patients with malignant tumors treated after 1966 were 75, 62, and 56 percent, respectively. Tumor stage was the most important prognostic variable. The ten-year overall survival rates were 83, 52, 25, and 23 percent for patients with stage I through IV disease, respectively. Patients with high-grade, low-stage adenocarcinoma or mucoepidermoid cancer had a cause-specific survival that was comparable to that observed for all low-grade cancers. Postoperative RT may play a role in reducing the rate of local recurrence, especially in those with positive margins after surgery. A benefit for adjuvant RT in high-risk cases was suggested in another series of 128 patients with malignant intraoral minor salivary gland tumors who were treated with either surgery alone (n = 59) or surgery followed by postoperative RT (n = 32); the remainder were either unresectable or refused surgical treatment RT was administered to patients with close or positive surgical margins or metastatic cervical lymphadenopathy. Although local recurrence rates were the same or slightly higher in the radiated patients, the fact that this group was selected for RT based upon poor prognostic features led the authors to postulate a beneficial effect of RT. The five-year survival rates were similar in the two groups (86 versus 88 percent, respectively SUMMARY AND RECOMMENDATIONS — Salivary gland tumors can arise from either the major (parotid and submandibular gland) or minor salivary glands. Although most parotid tumors are benign pleomorphic adenomas, the incidence of malignant tumors is higher when the submandibular and minor salivary glands are involved. Malignant tumors are heterogeneous both in their histologic appearance and clinical behavior. Treatment is predominantly surgical. There is a general consensus that patients with low-grade T1 and T2 primaries can be adequately treated by surgery alone. Postoperative radiation therapy (RT) is recommended to improve local control for larger or more invasive malignant tumors (most T3/4) and malignant salivary gland neoplasms in the following circumstances:
In addition, because of the unique affinity of adenoid cystic carcinoma for neural involvement, many authors recommend routine postoperative radiotherapy regardless of stage or margin status, although this is somewhat controversial. Adjuvant RT should also be considered for minor salivary gland tumors involving the nasopharynx, regardless of grade or size. |
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cm) tumors, a more extensive resection may be necessary and neck
dissection should be performed