Failure patterns and factors affecting prognosis of salivary gland carcinoma: retrospective study

PML Teo, ATC Chan, WY Lee, SF Leung, ESY Chan, CO Mok
Department of Clinical Oncology, The Chinese University of Hong Kong, Prince of Wales Hospital, Shatin, Hong Kong

OBJECTIVES. To investigate the failure patterns and the prognostic factors following postoperative radiotherapy for salivary gland carcinoma.

DESIGN. Retrospective study.

SETTING. University teaching hospital, Hong Kong.

PATIENTS. Fifty patients who had non-disseminated salivary gland carcinoma and who received primary treatment from 1984 through 1993.

MAIN OUTCOME MEASURES. Demographic data, cancer T- and N-stages, histological type, site of origin, completeness of surgery, whether postoperative radiotherapy was given, and the clinical outcome.

RESULTS. Two (4%) patients had been treated with radiotherapy alone, six (12%) had undergone radical resection alone, and 42 (84%) had been radically treated by using both modalities. The 5-year overall survival and relapse-free survival rates were 78.4% and 63.1%, respectively. The free from local failure and free from distant metastasis rates at 5 years were 77.2% and 72.8%, respectively. The N-stage was a significant prognostic factor. The site of the primary tumour, T-stage, completeness of surgery, and use of postoperative radiotherapy were not significant independent prognosticators; however, among the T-stage tumours, the b-substage carcinomas had significantly fewer local failures (P=0.040) and better survival rates (P=0.038) than the a-substage carcinomas. There were seven (14%) locoregional failures without distant metastasis, seven (14%) cases of distant metastasis without locoregional failures, and four (8%) locoregional failures preceding distant metastasis; isolated regional relapse was rare (1/50; 2%). All regional failures (5/50; 10%) occurred ipsilateral to the primary lesion. There were no deaths due to lymphoepithelioma-like carcinoma or acinic cell carcinoma.

CONCLUSIONS. The N-stage is the main prognostic factor of overall survival, relapse- and metastasis-free recovery, and success of treatment for salivary gland carcinoma. Optimal locoregional treatment can help reduce distant metastasis, and the maximal use of postoperative radiotherapy may contribute to improved locoregional control. Elective ipsilateral neck radiotherapy is indicated for lymphoepithelioma-like carcinoma.

Hong Kong Med J 2000;6:29-36

Key words: Combined modality therapy; Prognosis; Radiotherapy, high-energy; Salivary gland neoplasms/therapy; Survival analysis; Treatment outcome