Save your tears.

In the world of increasing radiosurgery utilization, whole brain radiation therapy (WBRT) has decreased appeal, largely due to its negative impact on cognition. However, we also know about the negative side effects WBRT has on in-field gland secretion. Researchers from the University of North Carolina are at it again to prospectively assess patient-reported dry eye syndrome after WBRT—which admittedly isn’t often assessed by anyone else. Patients received 25-40 Gy of WBRT with dry mouth as the primary endpoint and dry eye syndrome as a secondary endpoint. Lacrimal glands were not prospectively delineated, as is typical for WBRT, but they were retrospectively identified with MRI fusion. Where are the lacrimals? They’re the blob of tissue squished between the superior-lateral globe and lateral orbital wall. A correlation between lacrimal gland dosimetry and worsening dry eyes was indeed identified. Specifically, a V20 Gy ≥ 79% was associated with significantly higher rates of worsening dry eyes after WBRT. It appears the trick to meeting this constraint would be to cover most of the lacrimal gland with an MLC (similar to the lens). TBL: Minimizing dose to the lacrimal gland with an MLC during WBRT is an easy way to reduce the chances that your palliative treatment gives your patients dry eye. | Wang, IJROBP 2019