Poster Presentation COSA 2015 ASM

Salivary Duct Carcinoma: Clinicopathologic Features, Morphologic Spectrum and Somatic Mutations (#386)

Peter P Luk 1 , Jared D Weston 2 , Bing Yu 3 4 , Christina I Selinger 1 , Rafael Ekmejian 5 , Timothy J Eviston 6 , Trina Lum 1 , Kan Gao 6 , Michael Boyer 3 7 , Sandra A O’Toole 1 3 4 , Jonathan R Clark 3 6 7 , Ruta Gupta 1 3
  1. Tissue Pathology and Diagnostic Oncology, Royal Prince Alfred Hospital, Sydney, NSW, Australia
  2. Westmead Hospital, Sydney, NSW, Australia
  3. Central Clinical School, The University of Sydney, Sydney, NSW, Australia
  4. Department of Medical Genomics, Royal Prince Alfred Hospital, Sydney, NSW, Australia
  5. University of New South Wales, Sydney, NSW, Australia
  6. The Sydney Head and Neck Cancer Institute, Sydney, NSW, Australia
  7. Department of Medical Oncology, Chris O'Brien Lifehouse, Sydney, NSW, Australia

Background: Accurate diagnosis of salivary duct carcinoma (SDCa) requires a high index of suspicion and clinicopathologic correlation. Hallmark genetic changes that may provide novel therapeutic options are being explored. 

Methods: 190 salivary gland malignancies at Royal Prince Alfred Hospital (1989-2014) were reviewed. HER2 and androgen receptor status were determined along with multigene profiling.   

Results: 23 SDCa were identified, predominantly in men in 5th-9th decade. Facial nerve palsy (12%) and cervical lymph node metastases (82%) were present, and 96% received post-operative adjuvant therapy. Histologically, the tumors resembled high-grade invasive and in-situ ductal carcinoma of breast. The tumours showed androgen receptor (70%), HER2 amplification (30%) and HRAS, AKT1, PIK3CA and NRAS mutations (22%; cumulative). Nearly 52% developed systemic metastases and the five-year disease free survival was 36%.

Conclusions: SDCa demonstrate a wide histopathologic spectrum. Our data highlight that systemic treatment should be the priority in patients with nodal metastases or LVI. The importance of accurate diagnosis, therapeutic target testing such as HER2 and androgen receptor status along with further studies investigating novel systemic agents cannot be overstated.