title: Clinicopathological features and treatment outcomes of the rare, salivary duct carcinoma of parotid gland.
abstract: BACKGROUND
  Salivary ductal carcinoma (SDC) of parotid gland is a rare and aggressive entity; accounting for 1-3 % of all malignant salivary gland tumors, 0.2 % of epithelial salivary gland neoplasms, 0.5 % of salivary gland carcinomas, and 1.1 % of parotid gland carcinomas. Here in we aimed to evaluate the clinico-pathological features and treatment outcomes of parotid gland SDC in Saudi population.
  
  
  METHODS
  Among 38 patients with parotid malignancies, who were treated in two major tertiary care referral cancer centers between December 2007 and December 2014, seven cases (18.4 %) were found to have SDC, which were investigated for clinicopathological features, locoregional recurrences (LRRs), distant metastasis (DM) and survival rates.
  
  
  RESULTS
  Mean age of cohort was 62.3 years (range: 41-83) and female predominant (71.4 %). All patients underwent total parotidectomy and ipsilateral neck dissection. Mean tumor size was 3.4 cm (range: 2.1-5.3); perineural invasion (85.8 %); lymph node involvement (42.9 %); and HER-2 neu overexpression (28.6 %). Postoperative radiation therapy (PORT) was given to six patients (dose: 50-66 Gy). Median follow-up was 20.2 months (range: 11-48). LRRs were seen in five (71.4 %) patients (base of skull, 3 patients; cervical nodes, one patient; parotid bed, one patient). LRRs were salvaged with resection (two patients) and re-irradiation (one patient with base of skull). DM in lungs was seen in three patients (42.8 %); one treated with carboplatin/paclitaxel based chemotherapy. The 4-year disease free and overall survival rates were 16.7 % and 40 % respectively.
  
  
  CONCLUSIONS
  SDC of parotid gland is a rare and aggressive entity, and most of LRRs were seen in the base of skull, which warrants inclusion of base of skull in clinical target volume in PORT planning. Role of anti HER-2 targeted therapy in SDC with HER-2 neu overexpression needs further investigations.
authors.affiliation: Department of Otolaryngology-Head & Neck Surgery, College of Medicine, King Saud University, Riyadh, Saudi Arabia.
authors.forename: Khalid Hussain
authors.initials: KH
authors.lastname: Al-Qahtani
authors.affiliation: Radiation Oncology, King Fahad Medical City, Riyadh, 59046, Saudi Arabia. drmutahirtonio@hotmail.com.
authors.forename: Mutahir A
authors.initials: MA
authors.lastname: Tunio
authors.affiliation: Radiation Oncology, NCI, Cairo University, Cairo, Egypt.
authors.forename: Yasser
authors.initials: Y
authors.lastname: Bayoumi
authors.affiliation: Radiation Oncology, King Fahad Medical City, Riyadh, 59046, Saudi Arabia.
authors.forename: Venkada Manickam
authors.initials: VM
authors.lastname: Gurusamy
authors.affiliation: Faculty of Medicine, King AbdulAziz University, Riyadh, 59046, Saudi Arabia.
authors.forename: Fahad Ahmed A
authors.initials: FA
authors.lastname: Bahamdain
authors.affiliation: Histopathology, Comprehensive Cancer Center, King Fahad Medical City, Riyadh, 59046, Saudi Arabia.
authors.forename: Hanadi
authors.initials: H
authors.lastname: Fatani
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D015331:Cohort Studies; D003131:Combined Modality Therapy; D005260:Female; D006801:Humans; D008279:Magnetic Resonance Imaging; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000000981:diagnostic imaging; D010306:Parotid Gland / Q000000981:diagnostic imaging / Q000473:pathology* / Q000601:surgery; D018719:Erb-b2 Receptor Tyrosine Kinases / Q000378:metabolism; D018987:Salivary Ducts / Q000473:pathology*; D012468:Salivary Gland Neoplasms / Q000401:mortality / Q000473:pathology* / Q000532:radiotherapy / Q000601:surgery; D017678:Sex Distribution; D016019:Survival Analysis
chemical_list: D018719:Erb-b2 Receptor Tyrosine Kinases; C508053:ERBB2 protein, human
keywords: Parotid gland; Salivary ductal carcinoma; Saudi population