Intraoral adenoid cystic carcinoma: prognostic factors and outcome

Intraoral (oral cavity and oropharynx) adenoid cystic carcinomas are uncommon cancers characterized by slow evolution, protracted clinical course, multiple and/or delayed recurrences, and late distant metastases. The molecular biology behind this enigmatic disease remains poorly characterized. To analyze and correlate prognostic factors with outcome in intraoral adenoid cystic carcinoma. Medical records of 76 patients with intraoral adenoid cystic carcinoma treated with definitive loco-regional therapy at the institute between 1992 and 2004 were retrospectively reviewed and analyzed.Majority (85.5%) of the patients had advanced stage disease. Seventy-four patients underwent surgery, of which 51 (68.9%) received adjuvant radiotherapy. The median dose of radiation was 56 Gy (range 44-66 Gy). Two patients with medical co-morbidities received radical radiotherapy. Perineural invasion, margin positivity and nodal positivity were present in 24 (32.4%); 27 (36.4%); and 15 (19.7%) patients, respectively. Ten (13.1%) patients developed local recurrence and 6 (7.8%) distant metastases. With a median follow-up of 20 months (range 1-137 months), the 5-year Kaplan-Meier estimates of local control and disease-free survival were 57.9% and 47.1%, respectively. On uni-variate analysis, perineural invasion (p=0.003), oropharyngeal primary (p=0.033), and advanced T-stage (p=0.047) were associated with increased local recurrences. Perineural invasion (p=0.05) and primary site (p=0.042) also predicted disease-free survival. On multivariate analysis, both perineural invasion and primary site retained significance for local control (p=0.007, p=0.011) and disease-free survival (p=0.018, p=0.014), respectively. Intraoral adenoid cystic carcinoma is an uncommon disease with an enigmatic clinical course. Perineural invasion, site of primary, and T-stage significantly impact upon local control and disease-free survival. The role of adjuvant radiotherapy remains controversial. Larger prospective studies with mature follow-up are needed to define the optimal treatment of intraoral adenoid cystic carcinoma.