Impact of adjuvant therapy on survival in patients with myoepithelial carcinoma: A systematic review and individual patient data analysis of 691 patients.

Abstract

Myoepithelial carcinoma (MEC) is an extremely rare low grade salivary gland neoplasm [1-4]. A surgical resection is considered as corner stone of therapy. Role of adjuvant therapy is not clear. We performed systematic review and individual patient data analysis of 691 patients to look into the impact of adjuvant therapy and different prognostic variable for MEC. Data of 691 individual patients were retrieved from 340 publications. Median age of presentation was 56 years (Range: 0-103 years) with a trend of increasing incidence for increase in age. Major salivary glands (36.4%) were the commonest sub-site followed by minor salivary glands, skin and soft tissue, and breast. Median PFS and OS of entire cohort was 48 months (95% CI: 30-65 months) and 167 months (95% CI: 82-251 months). In univariate analysis A R0 resection was associated with significantly better PFS and OS. Median PFS and OS were significantly worse for patients with tumour size >5 cm compared to smaller tumours and for patients with a mitotic index >10/10 high power field (hpf) compared to lower mitotic index. Adjuvant radiation was found to reduce loco-regional recurrence. Adjuvant radiation and chemotherapy both were associated with negative impact on survival in univariate analysis. This negative impact on survival was lost in multivariate analysis. MEC appears to be a low grade malignancy with good survival outcome. A R0 resection should be the standard of care. Adjuvant radiation should be considered for patients with adverse risk features to improve loco-regional disease control.