Patterns of local failure for sinonasal malignancies.

To identify the patterns of local failure for sinonasal malignancies treated with radiation therapy (RT).We retrospectively identified 79 patients with sinonasal malignancies treated between 2000 and 2011. The median follow-up was 34 months (7-137). Fifty patients (63%) had surgery and RT with or without chemotherapy, and 29 (37%) received definitive chemoradiation therapy. Twenty-six of 79 patients (33%) failed locally; 11 had persistent disease and 15 had local recurrence (LR). The patients with LR had at least a 3-month disease-free interval posttreatment. Imaging of the 15 LR was registered to the treatment planning computed tomography. Failures were categorized as in-field, marginal, or out-of-field if >95%, 20%-95%, or <20% of the LR was within the 95% prescription isodose line, respectively.Of the 15 patients with LR, 7 were in-field, 2 were marginal, and 6 were out-of-field. For 3 patients, treatment plans were not retrievable; however, it was apparent from clinical records that 2 had in-field LR and 1 had an out-of-field LR (untreated contralateral maxillary sinus). No patient with a marginal or out-of-field recurrence had more than 39% of their recurrent tumor volume within 95% of the prescribed dose. Coverage of the LR by 54 Gy and 45 Gy was suboptimal in 7/7 and 5/7 patients with LR, respectively. Marginal and out-of-field LR were predominantly above the pretreatment tumor location and at the level of or superior to the eyes.Sinonasal malignancies failed marginally or out-of-field in 53% (8/15) of LR and 31% (8/26) of all local failures. The anatomic location of these marginal and out-of field LR are predominately at, or superior to, the level of the eyes. This pattern of failure may be directly related to efforts to minimize RT to the optic structures and the degree of difficulty of skull base operations.