Chemoreduction for Group E Retinoblastoma: Comparison of Chemoreduction Alone Versus Chemoreduction Plus Low-Dose External Radiotherapy in 76 Eyes

Abstract

To evaluate chemoreduction (CRD) for group E retinoblastoma. Retrospective, comparative case series. Seventy-six eyes of 56 patients with group E retinoblastoma were treated with CRD alone or CRD plus low-dose prophylactic external beam radiotherapy (CRD+P-EBR). The CRD included vincristine, etoposide, and carboplatin (6 cycles). The P-EBR was given routinely 2 months after completion of CRD at a suggested dose of 2600 cGy. Therapeutic EBR (T-EBR) was only given at the time of extensive tumor recurrence at a suggested dose of 3800 cGy. Retrospective chart review. Globe salvage. Of the 76 eyes, 64 received CRD alone and 12 received CRD+P-EBR. At the 2-year follow-up, globe salvage was achieved in 29 (53%) of 55 eyes in the CRD group and in 10 (91%) of 11 eyes in the CRD+P-EBR group. At 5 years, globe salvage was achieved in 20 (48%) of 42 eyes in the CRD group and in 4 (80%) of 5 eyes in the CRD+P-EBR group (P=0.347). Of the 64 eyes in the CRD group, 16 (25%) were salvaged with CRD alone and 13 (20%) with CRD+T-EBR, whereas 22 (34%) were enucleated after CRD alone and 13 (20%) were enucleated after CRD+T-EBR. Of the 12 eyes in the CRD+P-EBR group, 10 (83%) were salvaged with CRD+P-EBR, whereas 2 (17%) were enucleated and none required T-EBR. The median dose for T-EBR was 3800 cGy, and that for P-EBR was 2600 cGy. Eyes treated with CRD+P-EBR showed significantly less recurrence, leading to less chance of enucleation or therapeutic radiotherapy than that for CRD alone (P<0.001). Visual acuity was 20/100 or better or fix and follow in 9 (32%) of 28 salvaged eyes in the CRD group and in 4 (40%) of 10 in the CRD+P-EBR group. At 5 years, there were no patients in either group with metastasis of pinealoblastoma or who had died. In one patient in the CRD group, a second cancer developed. Group E retinoblastoma managed with CRD+P-EBR showed significantly less need for enucleation or therapeutic radiotherapy than eyes treated with CRD alone. These findings merit further study and consideration.