[Adenoid cystic carcinoma of the head and neck: a retrospective series of 169 cases]

Purpose: Adenoid cystic carcinoma represents 1% of head and neck cancers. Adenoid cystic carcinomas are slow growing tumours with high potential for local recurrence. Treatment usually associates radiotherapy and surgery, but the role of radiotherapy remains unclear. We report a retrospective multicentric study of the management and prognostic factors of 169 adenoid cystic carcinomas of head and neck.

Patients and methods: Between 1982 and 2010, 169 patients with adenoid cystic carcinoma of the head and neck were referred to the Cercle des oncologues radiothérapeutes du Sud departments of radiotherapy either for primary untreated tumour (n=135) or for a recurrence of previously treated tumour (n=34). The site of adenoid cystic carcinoma was: parotid gland (n=48, 28.4%), minor salivary gland (n=35, 20.7%), submandibular gland (n=22, 13%), sinus cavities (n=22, 13%), other (n=42, 24.9%). Tumour stages were: T1 (12.4%); T2 (14.2%); T3 (12.4%); T4 (41.4%) and Tx (19.5%). Lymph node involvement was 13% and distant metastasis 8.9%. For adenoid cystic carcinomas of the parotid gland, major nerve involvement was evaluated. Preferential site of metastasis was the lung (87.5%). Treatments were: surgery alone (n=27), surgery and adjuvant radiotherapy (n=89), surgery and adjuvant chemoradiotherapy (n=12), exclusive chemoradiotherapy (n=13), exclusive radiotherapy (n=14), other associations (n=5) and no treatment (n=7). Radiotherapy was delivered through photons (n=119), neutrons (n=6), both (n=4). Two patients had a brachytherapy boost. Median prescribed doses to T and N were respectively 65 Gy and 50 Gy for the 119 photons treated patients.

Results: Mean follow-up was 58 months (range 1-250 months). As of December 1, 2010, 83 patients were alive with no evolutive disease (49%), 35 alive and had recurred, 18 had uncontrolled evolutive disease, 28 had died of adenoid cystic carcinoma and 5 of intercurrent disease. Overall survival and disease free survival were respectively 72% and 72% at 5 years, 53% and 32% at 10 years; 5 and 10-year freedom from local recurrence were 81% and 52% respectively. Nerve involvement was found in 17/48 parotid gland adenoid cystic carcinomas. The Cox model including all patients, showed that surgery (P<0.001), surgical margins (P=0.015), nerve involvement (P=0.0079), length of radiotherapy (P=0.018), and tumour location (P=0.041) were associated with disease free survival.

Conclusion: In this large series of adenoid cystic carcinoma of head and neck with a majority of T3-T4 tumours, 10-year survivals were achieved for 50% of patients. Radiotherapy did not impact survival.