Inr. J. Radiation Oncology Bml. Phys., Vol. 26, pp. 625-630 Printed zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA in the U.S.A. All rights reserved. 0360-3016/93 $6.00 + .OO Copyright 0 1993 Pergamon Press Ltd. ?? Clinical Original Contribution zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDC CATARACTOGENESIS AFTER COBALT-60 EYE PLAQUE RADIOTHERAPY MARKUS KLEINEIDAM, M.D.,’ JAMES J. AUGSBURGER, M.D.,’ CARLOS HERNANDEZ, M.D.,2 PATRICK GLENNON, M.S.2 AND LUTHER W. BRADY, M.D.2 ‘Oncology Unit, Retina Service, Wills Eye Hospital, Jefferson Medical College; and %he Department of Radiation Oncology and Nuclear Medicine, Hahnemann University, Philadelphia, Pennsylvania, USA Purpose: This study zyxwvutsrqponmlkjihgfedcbaZYXWVUTSRQPONMLKJIHGFEDCBA was designed to estimate the actuarial incidence of typical postirradiation cataracts and to identifyprognostic factors related to their development in melanoma-containing eyes treated by Cobalt-60 plaque radiotherapy. Our special interest was the impact of calculated radiation dose and dose-rate to the lens. Methods and Material: The authors evaluated theactuarial occurrence of post-irradiation cataract in 365 patients with primary posterior uveal melanoma treated by Cobalt-60 plaque radiotherapy between 1976 and 1986. Results: Only 22% (S.E. = 4.6%) of the patients who received a total dose of 6 to 20 Gy at the center of the lens developed a visually significant cataract attributable to the radiation within 5 years after treatment. Using multivariate Cox proportional hazards modeling, the authors identified thickness of the tumor, location of the tumor’s anterior margin relative to the equator and the ora serrata, and diameter of the eye plaque used as the best combination of covariables for predicting length of time until development of cataract. Surprisingly, the dose of radiation delivered to the lens, which was strongly correlated to all of these covariables, was not a significant predictive factor in multivariate analysis. Conclusion: The results suggest that success of efforts to decrease the occurrence rate of post-irradiation cataracts by better treatment planning might be limited in patients with posterior uveal melanoma. Uveal melanoma, Cataract, Brachytherapy, Cobalt-60 eye plaques. INTRODUCTION On the basis of currently available, non randomized but statistically-adjusted comparative survival studies, epi- scleral plaque radiotherapy and enucleation (21) are be- lieved to be nearly equivalent in terms of the survival prognosis of patients having a posterior uveal malignant melanoma ( 1-7, 9, 19). If this is true, plaque treatment has the advantage of preserving vision, at least to some degree, in the tumor-containing eye in a substantial pro- portion of patients for intervals of up to 5 years or even longer. Unfortunately, the great majority of patients treated by episcleral plaque radiotherapy lose a substantial portion of their vision over 5- 10 years, largely on the basis of radiation-related complications ( 15). One of the most widely recognized and common com- plications of episcleral plaque brachytherapy in eyes with primary posterior uveal melanoma is cataract formation (8, 14, 15, 17). The classic features of post-irradiation cat- aract, as described by Cogan, Donaldson and Reese in 1952 (lo), include posterior subcapsular lens clouding caused by damage to the subcapsular epithelium. In spite of the fact that post-irradiation cataracts are well-known to ophthalmologists, the actuarial incidence of this form of cataract following specific methods of ocu- lar radiotherapy has not been reported. This study was designed to estimate the actuarial incidence of typical postirradiation cataracts and to identify prognostic factors related to their development in melanoma-containing eyes treated by Cobalt-60 plaque radiotherapy. Our special in- terest was the impact of calculated radiation dose and dose-rate (12) to the lens. METHODS AND MATERIALS Patients Four hundred patients with posterior uveal malignant melanoma were treated primarily by Cobalt-60 plaque radiotherapy at Wills Eye Hospital, Philadelphia, between Reprint requests to: James J. Augsburger, M.D., Oncology Unit, Retina Service, Wills Eye Hospital, 900 Walnut St., Phil- adelphia, PA 19 107, USA. Acknowledgement: The authors would like to acknowledge Jerry A. Shields, M.D., who managed some of the patients evaluated in this study. 625 This study was supported in part by a grant from the Deutsche Krebsgesellschaft, Dr. Mildred Scheel Stiftung, Bonn, Germany, to Dr. Markus Kleineidam, and an unrestricted grant from Re- search to Prevent Blindness, Inc., New York, NY, U.S.A., to Wills Eye Hospital. Accepted for publication 15 February 1993.