Dry eye after whole brain radiation: Analysis from a prospective study.

Abstract

198 Background: Lacrimal glands (LGs) receive incidental dose of unknown significance in patients undergoing whole brain radiation therapy (WBRT). Median survival following diagnosis of brain metastases is poor, so quality of life is of utmost importance for these patients. We enrolled patients on a prospective observational cohort study with an endpoint of dry eye syndrome, which is not thought to be a toxicity of WBRT. Methods: Patients receiving WBRT for any diagnosis to a total dose of 25 to 40 Gy in 10 to 20 fractions were eligible. Patients received 3D-conformal WBRT using opposed lateral fields covering the skull and C1 or C2 vertebrae. LGs were not prospectively contoured before treatment but were subsequently contoured for dosimetric analysis. Patients completed the single-question Subjective Evaluation of Symptom of Dryness (5-point Likert scale) at baseline, immediately after WBRT (EndRT), 1 month (1M), 3 months (3M), and 6 months (6M). The primary endpoint was change in proportion of patients at 1M experiencing moderate or worse dry eye (defined as symptoms that cause discomfort and interfere with activities). Orbital dose was analyzed as a surrogate for LG dose as LGs were difficult to contour on computed tomography (CT) imaging. Results: 73 enrolled patients were eligible for analysis. There were 69 evaluable patients at EndRT, 55 at 1M, 33 at 3M, and 28 at 6M. Most patients received 30 Gy in 10 fractions. Median bilateral orbit mean dose was 17 Gy. Median bilateral lacrimal mean dose was 25 Gy. Median survival was 8 months. At baseline, 4% of patients had moderate or worse dry eye versus 9% at EndRT, 11% at 1M (1-tailed sign test, p = 0.031), 9% at 3M, and 7% at 6M. No significant relationship was noted between presence of dry eye and CT-contoured lacrimal gland or orbit doses. Conclusions: WBRT appears to cause a small increase in dry eye symptoms. A correlation between dry eye and LG dose was not observed, perhaps due to the overall low rate of toxicity, uncertainty in CT-based contouring of the LGs, set-up variations between planned and delivered doses, and the possibility of non-radiation causes of dry eye. Nonetheless, physicians should be aware of the possible occurrence of dry eye after WBRT, given its potential effects on quality of life.