title: Lower Respiratory Tract Adenoid Cystic Carcinoma: Its Management in the Past Decades.
abstract: OBJECTIVE
  Adenoid cystic carcinoma of the lower respiratory tract is a rare indolent neoplasm with prolonged survival, propensity for recurrences and metastasis years after initial therapy. We aim to study a 1,700-bed single tertiary academic hospital's long-term experience with ACC of the lower respiratory tract from the larynx to the lungs and review published literature on this subject.
  
  
  METHODS
  We analysed the clinicopathology, treatment options and outcome in 33 patients and reviewed the published literature over the last five decades.
  
  
  RESULTS
  The tumour has no gender predilection, a peak incidence in the fifth decade and is not related to smoking. Insidious symptoms are often treated as benign obstructive airway disease and infection; negative signs and normal chest X-rays delayed diagnosis. The tumour was distributed most commonly in the trachea followed by main bronchi, lobar bronchi and larynx. About 22% of patients required emergent bronchoscopic intervention to secure airway patency before definitive therapy with surgery or/and radiotherapy. A high proportion of resected specimens had positive margins. Overall survival and disease-free survival rates at 5 years were 81 and 62%, respectively, and at 10 years 70 and 54%, respectively. Prolonged good palliation was achieved for patients with unresectable lesions with radiation and wide armamentarium of endoscopic therapy.
  
  
  CONCLUSIONS
  In time, many patients eventually succumb to this disease. However, advances in medical skill and technology have prolonged survival while maintaining a good quality of life. Adenoid cystic carcinoma of the respiratory tract is a chronic life-long disease that may require interval intensive therapy. The challenge is to find the best therapeutic regimen aiming for a 'true' cure. Further study on the mutational landscape of adenoid cystic carcinoma may provide potential avenues for novel treatments to address a chemoresistant cancer.
authors.affiliation: Department of Respiratory & Critical Care Medicine, Singapore General Hospital, Singapore. Electronic address: anne.hsu.a.l@sgh.com.sg.
authors.forename: A A L
authors.initials: AA
authors.lastname: Hsu
authors.affiliation: Department of Medical Oncology, National Cancer Centre, SingHealth, Singapore.
authors.forename: E H
authors.initials: EH
authors.lastname: Tan
authors.affiliation: Department of Pathology, Singapore General Hospital, Singapore.
authors.forename: A M P
authors.initials: AM
authors.lastname: Takano
mesh_terms: D000328:Adult; D000368:Aged; D003528:Carcinoma, Adenoid Cystic / Q000473:pathology / Q000628:therapy*; D003131:Combined Modality Therapy; D019468:Disease Management; D005260:Female; D006801:Humans; D015994:Incidence; D008297:Male; D008875:Middle Aged; D009364:Neoplasm Recurrence, Local / Q000473:pathology / Q000628:therapy*; D009367:Neoplasm Staging; D010166:Palliative Care; D011379:Prognosis; D011788:Quality of Life; D012142:Respiratory Tract Neoplasms / Q000473:pathology / Q000628:therapy*; D012189:Retrospective Studies; D015996:Survival Rate; D013997:Time Factors; D055815:Young Adult
keywords: Bronchoscopic intervention; radiotherapy; salivary gland tumour; surgery; systemic therapy