Page 47 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

Natural history of recurrent pleomorphic adenoma
Introduction
Pleomorphic adenoma (PA) is the most frequent tumor of the major salivary glands, mainly affecting the parotid and has a reputation for recurrence and malignant transformation (MT). These two features along with the threat of facial nerve injury are the main concerns in the clinical management of patients with recurrent pleomorphic adenoma (RPA). In spite of improvements in treatment and outcome during the last 4 decades, the reputation for recurrence and malignant transformation lingers and is reinforced when a seemingly uneventful surgical procedure results in RPA. The fact that recurrent disease is now uncommon means data on the topic of RPA is sparse and the clinical picture obscure. This has led to different opinions on management and a general empathy towards, and low threshold for, repeated surgery whenever a recurrence is identified.
Information on RPA treatment outcome is available in two forms. The most common form is small single/two center studies that detail treatment results with varying inclusion criteria and endpoints, providing a confusing cloud of information. Another more structured form of reporting is based on nationwide databases pertaining to benign pleomorphic adenoma. These are rare because of a lack of national registries of the benign PA. Two large population-based studies have recently thrown light on the subject of RPA and MT incidence in a more comprehensive way [1,2]. These large series focused on primary tumor incidence, recurrence rate, MT and risk factors for recurrence. They are unique in scale, have a long follow-up after primary tumor treatment and do not suffer from the selection bias influencing the conclusions drawn from previous institutional series.
The intention of this study was to form a comprehensive picture of RPA behavior and subsequently present an updated view on its management. In this context, the two national data sets were used as a framework in which to fit the complimentary but fragmented information from the institutional series.
Materials and methods
The follow-up data of the only two previously published nationwide series of PA was pooled with a focus on risk of MT and analyzed against the background of
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