EXTRAPARENCHYMAL EXTENSION, LYMPH NODE INVOLVEMENT, AND A HIGHER KI67 INDEX WERE HIGH RISK FACTORS FOR WORSE PROGNOSIS IN CONVENTIONAL MAMMARY ANALOGUE SECRETORY CARCINOMA

Abstract

Objective The prognostic factors of salivary gland (mammary analogue) secretory carcinoma (SC) are unclear because of the rarity of the tumors. Here we presented the largest case series to investigate the prognosis related clinicopathological factors in salivary conventional SC. Findings The study was based on a retrospective cohort of patients whose sections were reviewed and newly diagnosed as SC by the detection of ETV6 rearrangement from 1993 to 2015. The clinicopathological features were analysed as the primary predictors and patients’ final outcome was collected. Survival analysis was performed in conventional SC by using Kaplan-Meier method and Cox proportional hazards regression model. In our study, totally sixty-two cases of SC were confirmed. Fifty-nine out of 62 cases were conventional SC with a mean age of 43.2 years, showing significant male predilection (49/59, 83.1%) and mostly occurred in parotid glands (49/59, 83.1%). Additional 3 cases were identified as SC with high-grade transformation (HG-SC), with a mean age of 20 years older than that of patients with conventional SC. Lymph node metastasis and Ki67 expression ≥10% were related to poor recurrence-free survival (RFS), distant disease-free survival (DDFS) and disease-free survival (DFS) in conventional SC. Significantly decreased RFS and DFS were seen in patients with extraparenchymal extension. T3/T4 stage, age greater than 44 years and markedly hyalinized fibrous septa were associated with worse DDFS. By using multivariate analysis, the Ki67 index was found to be an independent prognostic factor for RFS (p = 0.008) and DFS (p = 0.003) in conventional SC. Much more worse RFS and DFS were presented in HG-SC due to its aggressive behaviour. Conclusion In conventional SC, patients with extraparenchymal extension, lymph node involvement, and higher Ki67 index exhibited poor clinical outcome. Moreover, Ki67 was a potential predictor of RFS and DFS of conventional SC.