Adenoid Cystic Carcinoma of Salivary Glands. Case Series of 27 Patients

Abstract

Aim of the study: Adenoid cystic carcinoma (AdCC) is the second most common salivary gland cancer. This malignant tumor is characterized by its slow growth and in spite of the fact that it has a histological low - grade appearance, a prolonged clinical course usually lasting for years, repeated recurrences, development of distant metastases and high mortality rate are typical signs. New facts of its biological behavior as well as new fusion oncogenes probably responsible for its carcinogenesis were described in the last few years. In light of these facts, the authors evaluate their own case series of patients suffering from AdCC in this manuscript. Methods: The retrospective case series included 27 patients with AdCC, who were treated at the University Hospital in Pilsen in the last 30 years (01/1986-01/2016). Clinical and demographic para-meters were identified and evaluated. Detection of the 1p36 deletion and the tumor-specific MYB-NFIB fusion oncogene by fluorescence in situ hybridization were performed. Results: The incidence of AdCC in minor salivary glands, submandibular gland, parotid gland and sublingual gland was 41%, 26%, 22 % and 11% respectively. The following staging was observed: the 1st stage in 26%, the 2nd stage in 18%, the 3rd stage in 26% and the 4th stage in 30% of cases. Metastases to regional lymph nodes were diagnosed in 26% and distant metastases in 30% of patients (55% to lung, 27% to liver, 9% to bones and 9% of peritoneal metastases). The average follow-up was 76.4 ± 67.0 months (range 7-287 months). An outcome of the treatment during follow-up was as follows: 59% of patients were with no evidence of the disease, 22% of patients died because of the disease and 19% of patients were alive with a recurrence or metastases of AdCC. The MYB-NFIB fusion transcript was detected in 79% of cases (19/24) and the 1p36 deletion in 13% of cases (3/23). Conclusion: The AdCC of salivary glands shows a greater tendency to development of regional lymph node metastases than previously thought. The MYB-NFIB gene fusion is the major tumor-specific oncogenic event in AdCC with high detection rate. The MYB-NFIB fusion oncogene could currently only be used as a potential diagnostic tool in difficult histopathological cases of AdCC, especially in late distant metastases.

Keywords

• adenoid cystic carcinoma
• fusion oncogene
• biomarker
• myb-nfib