Salivary gland carcinomas - Monocentric experience on subtypes and their incidences over 42 years

Abstract

Salivary gland carcinomas are rare and heterogeneous. More than 20 subtypes are recognized and risk factors are diverse. The aim of this work was to evaluate the subtype and other risk factors in a monocentric population from more than four decades. 205 cases (diagnosis period 1972-2014) were retrospectively collected and analyzed with regard to the distribution of risk factors and their influence on overall survival (OS). 19/24 (79.2%) of the subtypes listed in the WHO classification occurred rarely in the cohort (< 5%). 10/24 (41.7%) of all subtypes were never diagnosed. With a total of 145/205 cases (70.7%), squamous cell carcinoma (PEC), adenocarcinoma (AdenoCa), acinar cell carcinoma (AcinarCa), mucoepidermoid carcinoma (MEC), and adenoid cystic carcinoma (ACC) were by far the most common subtypes. Risk factors are significantly different in these groups (e.g., lymphogenic metastasis and degree of differentiation in AdenoCa and age, T and UICC stage in PEC). The 5-year overall survival of all patients was 66.9% and differed significantly within the most common subtypes. An independent impact on overall survival was detectable for patient age (p<0.001), and T- (p=0.003) and N-stage (p=0.046) in multivariate analysis. Most subtypes occurred markedly rarely or not at all within decades. The most common diagnoses differ with respect to risk factors as well as OS and 3 risk groups can be defined based on histology. In conclusion, considering TNM alone is insufficient for prognosis estimation in salivary gland carcinoma.