Introduction

Carcinoma ex Pleomorphic Adenoma (CXPA) is a rare, malignant transformation of the most common benign salivary tumor – pleomorphic adenoma. Due to the myriad of pathologies, treatment controversies, and primary tumor locations, the 5-year overall survival associated with a diagnosis of CXPA ranges from 25-75% in the literature.5-7 While some prognostic factors are well established, the prognostic utility of margin status remains controversial.13,14 Given the rarity of CXPA and the paucity of data within the literature, we sought to provide our multi-institutional experiences on the management and associated outcomes for CXPA by evaluating overall survival (OS), disease specific survival (DSS), locoregional recurrence-free survival (LRFS), and factors impacting those outcomes.

Methods

We performed a multi-institutional retrospective cohort study of patients diagnosed with CXPA at the Queen Elizabeth II Health Sciences Center (QEII HSC, Halifax, Nova Scotia) from 2006-2023 and the University of Michigan (UM, Ann Arbor, MI, United States) from 2017- 2023. Adult patients with an index diagnosis of CXPA who underwent surgical treatment at QEII HSC and UM were identified through a QEII HSC institutionally housed pathology database and through Michigan’s Data Direct software with CPT codes for parotidectomy.

Results

37 patients were included in the study, nine of whom died over the follow-up period. Overall 2-year survival was 82% and 5-year survival was 61.7%. In cox univariate analysis, tumor size >4cm (HR 5.98, CI 1.22-29.2, p=0.027), stage 4 disease (10.98, CI 2.20-54.81, p=.004), lymphatic invasion (HR 4.89, CI 1.20-19.83, p=.027), extra nodal extension (HR 6.03, CI 1.59-22.85, p=.008), and positive margins (HR 5.15, CI 1.26-21.14, p=0.023) were associated with increased risk of death. In adjusted multivariable analysis, none of the variables remained statistically significant. Patients with a negative margin had a 5-year overall survival of 80.0%, compared to 50.0% in those with a positive margin.

Conclusions

Tumor size >4cm, stage 4 disease, lymphatic invasion, extra-nodal extension, and positive histopathologic margins may be associated with worse 5-year overall survival. Though current survival nomograms for CXPA do not factor margin status into survival probability, our data support that margin status may have a meaningful and understudied role to play in CXPA prognosis.

Tables and Figures

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