Clinicopathological characteristics and outcomes of 23 patients with secretory carcinoma of major salivary glands

Background Secretory carcinoma of salivary glands (SCSGs) are generally low-grade salivary gland carcinomas, and are characterized by morphological resemblance to mammary analogue secretory carcinoma and ETV6–NTRK3 gene fusion. Several reports on histopathological features of SCSG have recently been published; however, little is known about the clinical characteristics of this new tumor, including its outcomes. The research is to investigate the clinicopathological characteristics of secretory carcinoma of major salivary glands and to analyze outcomes of these carcinomas as a reference for standardizing their diagnosis and treatment. Methods The cohort of this retrospective study comprised 23 patients treated for histopathologically-confirmed SCSG between January 2010 and December 2020. Their clinical characteristics and outcomes were retrieved from patient files. Results The 23 patients comprised 13 male and 10 female patients (male:female ratio 1.3:1). They were aged 10–69 years (median 45 years) and the average duration of disease was 2.44 years (0.25–20 years). Twenty-one patients (91.3%) had SCSGs in the parotid gland and two (8.7%) in the submandibular gland. All 23 patients had single nodules with diameters of 0.8–4.8 cm (average 2.6 cm). Five patients had lymph node metastases and two had distant metastases. All tumors were pathologically diagnosed as SCSGs. Immunohistochemical staining was strongly positive for S-100, mammaglobin, CK7, and Gata3, and negative for Dog1, P63 and calponin. Ki-67 positivity ranged from 1–50%. Fluorescence in situ hybridization data were available for 15 patients, in all of whom ETV6 gene rearrangement was confirmed. All patients had undergone oncological resections. Four had radioactive particles implanted postoperatively, one received chemotherapy, and seven underwent chemoradiotherapy. Six patients had regional recurrences, two distant metastases, and one had died at the time of last follow-up. Conclusions SCSGs are typically indolent with a low rate of locoregional recurrence and excellent survival. Their prognosis is correlated with clinical stage, pathological grade, and surgical procedures performed.