3.2 I Cataract
Five patients developed bilateral cataracts at a median duration of 3.2
years (1.2 – 5.1 years) after completion of radiation (Table 3). All
these patients received CSI for embryonal tumors (4 medulloblastoma, 1
primitive neurectodermal tumor/PNET). The incidence of cataract was 12%
(5/42) in the cohort overall, and 38% (5/13) for those who received
CSI. Four patients had posterior sub-capsular cataracts, with details
not available for 1 patient who died due to disease, a few months after
cataract detection at an outside center. Three patients underwent
cataract surgery.
Of the 5 patients with cataracts after CSI, 2 each received 23.4 and 36
Gy RBE, and 1 received 25.2 Gy RBE to the whole brain and spinal cord,
with a median of 29.3 Gy to the lenses. The median radiation dose to the
lens for patients with cataract was significantly higher than that for
patients without cataract (Table 4).
Multivariable analysis identified CSI radiation volume, infratentorial
tumor location and the use of radiosensitizer chemotherapy as
significant risk factors for the development of cataract (Table 5) and
ocular complications overall (cataract and dry eyes) (Supplementary
Table 2). All 5 patients who developed cataract after CSI, had
infratentorial tumors, and 4 received radiosensitizing chemotherapy (2
Vincristine, 1 Carboplatin and Vincristine, 1 Temozolomide and
Irinotecan). Of the 13 patients in the cohort who received CSI, 12 had
infratentorial tumors (10 medulloblastoma, 1 mucoid spindle sarcoma, 1
primitive neurectodermal tumor in the cervical spinal cord). All 10
patients with medulloblastoma received weekly Vincristine during
radiation, and 1 received additional Carboplatin.
One patient with craniopharyngioma, with a normal eye exam prior to
radiation, developed left retinal scarring 2.2 years after, and cataract
3.5 years and 4.7 years in the left and right eyes, respectively, after
IFRT. She received both photon and proton radiation, and hence was
excluded from analysis.