Clinical significance of post-surgical residual tumor burden and radiation therapy in treating patients with lacrimal adenoid cystic carcinoma

Retrospective analyses were done on 19 lacrimal adenoid cystic carcinoma (ACC) patients who underwent curative treatment between 1997 and 2013. Nine patients (47.4%) had T1-2 disease and ten (52.6%) had T4 disease. Surgical procedures were globe-preserving tumor resection in 11 patients (57.9%), incisional biopsy in five (26.3%), and orbital exenteration was undertaken in three (15.8%). Residual tumor burdens were R0/1 in 12 patients (63.2%) and R2 in seven (36.8%). Radiation therapy (RT) was recommended to all patients, and 16 (84.2%) completed RT (median 60 Gy). After median follow-up of 57.5 months, seven (36.8%) developed progression and three (15.8%) died. Local recurrence occurred in four patients (21.1%), distant metastasis in one (5.3%), and combined local recurrence and distant metastasis in two (10.5%). Progression-free survival and overall survival rates at 5-years were 64.5% and 82.6%, respectively. Among 12 patients following R0/1 resection, two (16.7%) developed local recurrence and none died, while among seven following R2 resection, five (71.4%) developed progression and three (42.9%) died. RT following R0/R1 resection could reduce progression. Globe-preserving surgery and RT seemed optimal strategy for T1-2 disease. Careful attention should to be paid to minimize residual tumor burden at surgery and effort for safe radiation dose escalation would be desired.