Eyeworld

EW IN OTHER NEWS 128 October 2018 by Maxine Lipner EyeWorld Senior Contributing Writer whose tumors he treats don't receive follow-up at the Colorado facility where the study occurred. "We treat children from all the neighboring states including Wyoming, Mon- tana, and Kansas," Dr. Liu said, adding that they recommend their home institution follow up with hormonal or cognitive testing, as well as perform annual eye exams. Dr. Liu recommends that such an exam be conducted by an oph- thalmologist rather than an op- tometrist, since there can be retinal and other abnormalities that can be associated with radiation treatment. Determining when to remove any cataracts that may occur is be- tween the ophthalmologist and the family. "Many of our children were 3, 4, or 5 when they were treated, so they still have a lot of growing to do," Dr. Liu said. "Ideally, you would like to do one procedure and not have to repeat this." However, in some cases he has had 5-year- olds whose vision was so poor that immediate cataract surgery was necessary. "So you do the procedure, and you recognize that you might be doing it again when they hit puberty," he said. Dr. Liu hopes that ophthalmolo- gists come away from the study with a new awareness of the importance of routinely screening those who have undergone cranial radiation therapy for potential cataracts. EW Reference 1. Whelan RJ, et al. Radiation-induced cata- racts in children with brain tumors receiving craniospinal irradiation. J Pediatr Hematol Oncol. 2018;40:304–305. Editors' note: Dr. Liu has no financial interests related to his comments. Contact information Liu: arthur@alum.mit.edu Annual screening If children develop cataracts from such treatment, it is best if these are caught quickly. "Especially in school-aged children, if you don't recognize they're having trouble with vision, that can impair school achievement," Dr. Liu said. "The children don't always tell you they can't see the board, and those who have brain tumors have a lot of reasons why they don't do well at school." Unlike radiation dosage, spot- ting such cataracts is something that practitioners have a lot of control over. "To try to minimize the dura- tion that a child has symptomatic cataract, our group routinely follows everyone annually regardless of whether or not they're complaining of something," he said. However, a significant number of patients Studying irradiation effects A pproximately 30% of children with brain tumors who have under- gone radiation therapy developed cataracts within just a couple of years of treat- ment, according to Arthur Liu, MD, PhD, radiation oncologist, Poudre Valley Hospital, Fort Collins, Colora- do. Investigators reported on study results 1 indicating that children who underwent radiation treatment for medulloblastoma and other cranial tumors were at risk for potential development of posterior polar and other cataracts. This study was launched after an ophthalmologist at the Univer- sity of Colorado where Dr. Liu was at the time irradiating the children's tumors anecdotally noted that a sur- prising number were subsequently developing cataracts. "That prompt- ed us to look more formally at our own experience," Dr. Liu said. Cataract vulnerability This retrospective chart review included 45 children who received radiation to the entire brain area and spine. Investigators found that 13 of them developed cataracts in relatively short order. "We only had about a 2-year median follow-up," Dr. Liu said. "We would expect that rate to go up substantially as you follow these children longer." This had not previously been described in the literature and given the short follow-up took practitioners by surprise. While investigators knew that the lens was sensitive to radiation, for occupational exposure, as well as treatment, they thought there was greater latitude here. "Some of the early data suggested that if you kept this below 2 gray, this was sufficient," Dr. Liu said. "But more recent data suggests the lens is even more sensitive, and doses as low as half a gray are sufficient to induce cataracts." When it comes to treating brain tumors, however, cataracts are of secondary concern. "I'll never undertreat the tumor, recognizing that while cataracts are bad, having recurrent brain cancer is far worse," Dr. Liu said. In some children, there are different techniques that radiation oncologists can utilize to explicit- ly minimize the radiation dose to the lens. But this is not possible in all cases. "It has to deal with the distance between their lens and the inferior part of their brain," Dr. Liu said, adding that if this distance is great enough, it is possible to significantly reduce the radiation dose that reaches the lens. However, in very small children, where the anatomy is extremely tight, there's not much that can be done. Cataract development in children with cranial tumors In cases of whole brain irradiation, the treatment field, as depicted here, can put patients at risk for cataracts. Source: Arthur Liu, MD Research highlight

• Cover