Distribution and Frequency of Salivary Gland Tumours: An International Multicenter Study

Abstract

Background: Salivary gland tumours (SGT) are a relatively rare group of neoplasms with a wide range of histopathological appearance and clinical features. To date, most of the epidemiological studies on salivary gland tumours are limited for a variety of reason including being out of date, extrapolated from either a single centre or country studies, or investigating either major or minor glands only.

Methods: This study aimed to mitigate these shortcomings by analysing epidemiological data including demographic, anatomical location and histological diagnoses of SGT from multiple centres across the world. The analysed data included age, gender, location and histological diagnosis from fifteen centres covering the majority of the world health organisation (WHO) geographical regions between 2006 and 2019.

Results: A total of 5739 cases were analysed including 65% benign and 35% malignant tumours. A slight female predilection (54%) and peak incidence between the fourth and seventh decade for both benign and malignant tumours was observed. The majority (68%) of the SGT presented in major and 32% in the minor glands. The parotid gland was the most common location (70%) for benign and minor glands (47%) for malignant tumours. Pleomorphic adenoma (70%), and Warthin's tumour (17%), were the most common benign tumours whereas mucoepidermoid carcinoma (26%) and adenoid cystic carcinoma (17%) were the most frequent malignant tumours.

Conclusions: This multicentre investigation presents the largest cohort study to date analysing salivary gland tumour data from tertiary centres scattered across the globe. These findings should serve as a baseline for future studies evaluating the epidemiological landscape of these tumours.

Keywords: Demographics; Epidemiology; Head and neck; Histological diagnosis; Multicentre research study; Salivary gland neoplasms; Salivary gland tumours; Site distribution.

Fig. 1

Geographical map of the centres participating in the study including five from the UK, one from Europe, five from Africa, two from Asia and two centres from South America

Fig. 2

Age and gender distribution within the entire SGT cohort

Fig. 3

Anatomical site distribution of SGT. A major and minor gland distribution across the entire cohort. B Benign tumours in all glands. C Benign tumours in minor glands. D Malignant tumours in all glands. E Malignant tumours in minor glands

Fig. 4

Geographic comparison of the most common benign and malignant SGT. A benign tumours: PA-Pleomorphic adenoma, WT-Warthin tumour, BCA-Basal cell adenoma. B malignant tumours: MEC mucoepidermoid carcinoma, AdCC adenoid cystic carcinoma, PAC polymorphous adenocarcinoma, Ca ex PA carcinoma ex pleomorphic adenoma, ACC Acinic cell carcinoma

Fig. 5

Age and gender distribution for benign salivary gland tumours

Fig. 6

Anatomical site distribution of the most common benign SGT. Pleomorphic adenoma (PA), Warthin tumour (WT) and basal cell adenoma (BCA)

Fig. 7

Age and gender distribution for malignant tumours

Fig. 8

Anatomical site distribution of the most common malignant SGT. Mucoepidermoid carcinoma (MEC), adenoid cystic carcinoma (AdCC), polymorphous adenocarcinoma (PAC), carcinoma ex pleomorphic adenoma (Ca ex PA) and acinic cell carcinoma (ACC)