The role of radiotherapy for patients with adenoid cystic carcinoma of the salivary gland

Objective. Adenoid cystic carcinoma (ACC) is a rare malignant tumor occurring in the salivary gland that has some characteristic features, including slow growth, extremely diffuse invasion, and a high incidence of distant metastasis. The indication of radiotherapy (RT) for ACC is controversial. The aim of this study was to examine the usefulness of RT for patients with ACC. Study design. The study group was composed of 17 patients (18 lesions) with ACC of the salivary gland who underwent RT. They were divided into 3 groups: (1) those who underwent RT alone for a primary tumor, (2) those who underwent RT alone for a recurrent tumor after surgery, and (3) those who underwent postoperative RT because of a histologically positive surgical margin. The clinical course of each patient was examined retrospectively. Results. Of the 11 patients undergoing RT alone for a primary or recurrent tumor, 5 showed complete remission of the tumor, and 3 were free from local recurrence for a long period. Seven patients who underwent postoperative RT seemed to show better local control than did those who did not undergo postoperative RT, although there were no significant differences. Conclusions. We find RT to be an effective treatment procedure, especially for those who had an inoperable, advanced tumor or who had distant metastasis. Postoperative RT was recommended for those who had a histologically positive surgical margin.