Clinicopathological And Prognostic Analysis Of 62 Cases Of Mammary Analogue Secretory Carcinoma In A Chinese Population

Aims To analyse the clinicopathological,immunohistochemical and the molecular genetic characteristics of salivary mammary analogue secretory carcinoma(MASC)and the mammaglobin expression in non-MASC and to investigate the prognosis-related factors,diagnostic criteria,and treatment strategy of MASC in a Chinese population.Methods MASCs were retrospectively confirmed through histopathological observation,fluorescence in situ hybridization,RT-PCR and sequencing.The clinicopathological and immunohistochemical features and ETV6 gene alterations were analysed,and the follow-ups were performed.Immunohistochemical staining for mammaglobin was performed on 95 cases of non-MASC tumors.Results 1.Sixty-two cases of MASCs were identified and of which 57 cases were conventional MASC.The mean age of patients was 43.1 years and the tumors had a significant male predilection(47/57,82.5%).MASC occurred mostly in the parotid gland(47/57,82.5%).The other 5 cases were MASCs with high-grade transformation(HGT-MASC),with a mean age of 13.3 year older than that of conventional MASC.2.Most MASC cases(≥ 91.9%)showed CK8,S100,vimentin,mammalobin,and STAT5 a positivity,whereas few cases(≤ 4.8%)expressed p63,calponin,SMA,and DOG-1.Mammaglobin expression was observed in 29/95 cases of non-MASC salivary carcinomas.3.ETV6 break-apart was detected in all 62 cases,among which 4 cases demonstrated a complex pattern with an apparent duplication of the telomeric ETV6 gene simultaneously.4.Invasion of adjacent tissues,invasion of nerve,T3/T4 stage,and N1 stage were correlated with lower disease-free survival(DFS)(P<0.05).DFS for HG-MASC was significantly decreased compared to that of conventional MASC(P<0.001).Conclusion 1.MASC had a significant male predilection in Chinese populations.2.A 9-protein detection consisting of CK8,S100 protein,vimentin,mammaglobin,STAT5 a,p63,calponin,SMA,and DOG-1 played an important role in distinguishing MASC from other carcinomas.Some non-MASC salivary carcinomas can also show mammaglobin expression.3.Tumors with invasion of adjacent tissues,invasion of nerve,T3/T4 stage,and lymph node involvement exhibited worse prognosis.Close follow-up after radical surgical resection was recommended for conventional MASC,whereas neck dissection and postoperative radiochemotherapy should be performed for HGT-MASC.