Comparison of Paclitaxel plus Carboplatin versus Observation in Patients with Recurrent or Metastatic Adenoid Cystic Carcinoma of the Head and Neck.

INTRODUCTION: Although systemic therapy, including multi-kinase inhibitors and cytotoxic chemotherapy, is an option for recurrent or metastatic adenoid cystic carcinoma of the head and neck (HNACC), it is not proven whether these therapies can prolong overall survival (OS). The present study investigated the impact of cytotoxic chemotherapy on survival outcomes compared with observation without chemotherapy. METHODS: We retrospectively reviewed the medical records of the patients diagnosed with recurrent or metastatic HNACC. We compared the survival outcomes, including survival time from recurrence/metastasis (OS) patients who received systemic chemotherapy with paclitaxel (200 mg/m2) and carboplatin (area under the curve 6) (TC) on day 1 of a 3-week cycle and observation alone. Subgroup analysis was conducted to identify patients who can get benefit from TC. RESULTS: Seventy-five patients (32 in TC and 43 in observation) were analyzed. There was no difference in median OS between TC and observation (52.2 months vs. 44.0 months, hazard ratio 0.76, 95% confidence interval 0.32-1.30, p = 0.21). Landmark analysis to reduce immortal bias also showed no difference between TC and observation in terms of OS. Subgroup analysis showed nonsignificant trends toward longer OS in asymptomatic patients with pulmonary metastasis and without bone metastasis. CONCLUSIONS: In our non-randomized comparison, patients who underwent TC did not show prolonged survival time from recurrence and/or metastasis diagnosis compared with observation alone in patients with recurrent or metastatic HNACC. Although systemic chemotherapy is a possible option for metastatic/recurrent HNACC, initial observation might be a valid strategy for asymptomatic patients without extrapulmonary diseases. Further research is warranted to identify the optimal patients and therapeutic regimens to prolong OS in HNACC.