Management of adenoid cystic carcinoma of minor salivary glands.

PURPOSE: Adenoid cystic carcinoma (ACC) is a rare malignant tumor originating from the salivary glands. The characteristic clinicopathologic features of this tumor are perineural spread, local recurrences, and distant metastases. Radical surgery combined with radiotherapy, as mentioned in the literature, is the best method of treatment. This clinical review article is intended to analyze the outcome of management of a group of 22 ACC patients, who were treated in our clinic.
METHODS: Between 1985 and 2000, 22 patients with ACC of minor salivary glands were treated in the Clinic of Oral and Maxillofacial Surgery of the "G. Papanikolaou" General Hospital, in Thessaloniki. The age range was 22 to 87 years. The distribution of the primary sites was buccal mucosa (3), floor of the mouth (1), hard palate (3), soft palate (2), junction of hard and soft palate (7), and hard or soft palate with spread in the paranasal sinus etc (6). All the patients were treated radically with surgery. The surgery was combined with radiotherapy in 17 patients. A total dose of 60 Gy in a 30- to 40-day period was given, using conventional 2 Gy fractions per day. Immunohistochemical assay of the expression of the Ki-67 antigen was performed on a subset of 15 cases.
RESULTS: The mean follow-up range was 4 to 14 years. From the 22 patients, 15 (68.18%) were alive for more than 5 years and 6 (27.7%) had died from the disease. Eight patients were free of the disease for more than 5 years (ranging from 7 to 14), 4 patients were free of the disease for 5 years, and 3 patients were free of the disease for 4 years. One patient lived more than 10 years and died from another cause. Local recurrence was developed in 2 patients. One recurrence occurred within the first year after the treatment and the second local recurrence occurred 13 years after the initial treatment. Lymph node metastases occurred in 2 patients, 3 years and 7 years after completing the treatment. Distant metastases (lung) occurred in 2 patients, 2 years and 6 years after completing the treatment. The Mann-Whitney statistical analysis was used for comparing the Ki-67 values in correlation with prognosis and location of ACCs. The Ki-67 value was significantly higher in tumors from patients with treatment failure than in nonfailures (P < .001). The Ki-67 expression was also higher in large tumors characterized by wide topical spread (P < .005).
CONCLUSIONS: The most proper method of treatment for ACC seems to be radical resection combined with radiotherapy. The treatment failure is associated with positive margins of the excised surgical specimen and named nerve involvement. The immunohistochemical study of Ki-67 expression may provide additional prognostic information for this tumor.