Page 54 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

Chapter 3
Table 3: Clinicopathologic characteristics of Dutch and Danish patients (A-F) with a malignant transformation (MT) after a treated RPA (see also figure 2c).
Case A
B C D E F
Histology
Myoepithelial carcinoma
Adenocarcinoma NOS, grade III Myoepithelial carcinoma Salivary duct carcinoma Salivary duct carcinoma Myoepithelial carcinoma
Treatment
Surgery + RT
Surgery + RT Surgery + RT Surgery + RT Surgery + RT Surgery + RT
Clinical course (months)
LR 83 post MT; DOC 296 post PA (212 post MT)
NED 238
LR 35; NED 153 DOC 41
LR 21; DOD 29 LR 10, LR 23; DOC 61
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NOS= not otherwise specified; NED= no evidence of disease; LR= local recurrence; DOD= dead of disease; DM=distant metastases; DOC=dead of other causes
Facial nerve injury: This is the principal measure of surgical morbidity, and the risk of permanent facial nerve damage increases with number of surgeries. At the first RPA, facial nerve damage was 3-16% rising to 15-21% for 2nd recurrence to 18-30% for 3rd RPA (i.e. 4th operation) (Supplementary Table E) [6,15,20,22,26,27].
Discussion
The objective of this study was to provide a comprehensive overview of RPA behavior and address the current rational for its treatment. Namely, the focus lies on parotid RPA, as the risk of recurrence in other major as well as minor salivary glands is lower and does not confer a risk of facial nerve damage [2]. Historically, the management of patients with RPA has been directed largely by the fear of MT with incidences quoted from 0-24% and consequently a low threshold for repeated surgical intervention [13,31,32]. RPA poses an inherent problem for analysis, since it is uncommon but also because long follow-up is needed to trace the natural history of this disease. Consequently, most publications involve small series, and in many cases stretch back in time to the 1950/60’s where standards of reporting were different. The focus of the articles therefore varied, and the reporting of events was not uniform. The method adopted to provide insight into RPA behavior therefor was to pool data regarding patient, tumor, treatment and outcome characteristics from the most comprehensive epidemiological datasets and present it with the information obtained by a systematic review of the literature. Taking this approach, a natural history for RPA emerged from the previous opaque cloud of information and is sufficiently distinct to inform current thinking regarding the management of this disease.