Carcinoma ex Pleomorphic Adenoma: Multi-Institutional Retrospective Cohort Study.

OBJECTIVE

Carcinoma ex pleomorphic adenoma (CXPA) is a rare malignancy and survival rates vary throughout literature. The primary objectives are to study overall survival (OS), disease-specific survival (DSS), locoregional recurrence-free survival (LRFS), and secondarily margin status.

STUDY DESIGN

Multi-institutional retrospective cohort study.

SETTING

Queen Elizabeth II Health Sciences Center (QEII HSC) from 2006 to 2023 and the University of Michigan (UM) from 2017 to 2023.

METHODS

An institutional pathology database (QEII HSC) and parotidectomy database (UM) were used to identify 37 patients with CXPA who underwent surgical resection.

RESULTS

Most cases were locoregionally advanced with 51% being ≥T3 and 32% being cervical node positive. All cases were treated with surgery, 78% received adjuvant radiation. Overall, 2-year survival was 82% and 5-year survival was 61.7%. In univariate analysis, tumor size >4 cm, pathologic nodal stage ≥1, pathologic overall stage 4 disease, lymphovascular invasion, extranodal extension, and positive margins were associated with increased risk of death. In adjusted multivariable analysis, only pathologic nodal stage ≥1 (hazard ratio [HR] 9.474, confidence interval [CI] 1.19-75.41,  = .034) remained statistically significant. The 2-year LRFS was 80% and the 5-year LRFS was 75%. Of the 7 patients with locoregional recurrence, 6 had prior adjuvant radiation, and 4 recurred locally. Multivariable cox models for LRFS were not significant.

CONCLUSION

Patients with CXPA that metastasize to the neck have a worse prognosis. LRFS after surgery is 75% with high rates of adjuvant radiation. Further research on prognostic factors of LRFS and adjuvant radiation outcomes is required.