Lower Respiratory Tract Adenoid Cystic Carcinoma: Its Management in the Past Decades

Abstract

Aims: 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.

Materials and 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.

Keywords: Bronchoscopic intervention; radiotherapy; salivary gland tumour; surgery; systemic therapy.