Page 51 - New epidemiological and PSMA-expression based paradigms in salivary gland tumors

Natural history of recurrent pleomorphic adenoma
[1,2,29]. PA was more common in females, with a female to male ratio in Dutch and Danish series of 1.43:1 and 1.70:1 respectively (overall ratio 1.6:1). Similarly, in all series, a female preponderance was found among RPA patients (Supplementary Table A), but female gender was not a risk factor for recurrence [2]. The median age at presentation of the primary PA was ~50 years in the national series. In patients who later developed RPA, the age at presentation of the initial PA was 10-15 years younger than patients who did not develop recurrence [1,2,29,20]. The median age at 1st RPA was 40-49 (range 13-87) [1,6,18]. In at least 44% of cases, multiple nodules were clinically apparent and this was nearly 100% when the tissues were examined histologically, demonstrating that RPA is usually a multifocal disorder (Supplementary Table B) [12,19,26].
Treatment of recurrent pleomorphic adenoma
The surgical technique used initially to treat the primary tumor in the cohort of patients with tumor recurrence varied widely, with local excision/enucleation in up to 87% of patients in the older studies and 9% in more recent studies (Supplementary Table A) [6,27]. The risks of recurrence and facial nerve injury depended on the extent of previous PA- or RPA surgery [6,21]. This literature review does not provide adequate data to draw conclusions on the role of initial surgical technique regarding the risk of developing RPA and is therefore not explored further (Supplementary Table A and B). The extent of initial surgery, however, could be expected to impact on subsequent surgical options as a comprehensive form of salvage parotidectomy following a minimalist initial procedure would still be an option without undue risk to the facial nerve. In contrast, an initial parotidectomy followed by multinodular recurrence could be likely to be managed by either local excision of nodules, or an extended/radical parotidectomy [13]. There was too much heterogeneity in the literature to draw general conclusions on optimal surgical RPA treatment. Postoperative RT, however, seems to reduce the risk of recurrence. Renehan et al. showed a significant decrease in recurrence rate in the cohort of patients with multinodular recurrence that received postoperative vs no RT: 4% vs 43% at 15 years follow-up [6]. The control rate in other series similarly showed reduced recurrence rates following RT, and Chen et al. reported a control rate of 94% after a median follow-up of 17 years in patients with postoperative RT [4,8,30]. Recurrence after surgery with gross macroscopic residual disease and RT, was higher [16].
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