PREDICTIVE FACTORS FOR THE DEVELOPMENT OF SECONDARY GLAUCOMA AFTER STEREOTACTIC RADIOSURGERY FOR CHOROIDAL MELANOMA
Authors:   N. N. Alexandrov National Cancer Centre of Belarus, Minsk, Belarus, Zherka I. Y. , Dziameshka P. D. ,   N. N. Alexandrov National Cancer Centre of Belarus, Minsk, Belarus, Naumenko L. V. ,   N. N. Alexandrov National Cancer Centre of Belarus, Minsk, Belarus, Zhyliayeva K. P. ,   N. N. Alexandrov National Cancer Centre of Belarus, Minsk, Belarus, Hizemava V. A. ,   N. N. Alexandrov National Cancer Centre of Belarus, Minsk, Belarus, Polyakov S. L. ,   N. N. Alexandrov National Cancer Centre of Belarus, Minsk, Belarus
Published: July 2022

Stereotactic radiosurgery (SRS) demonstrates satisfactory results in terms of local tumor control and survival of patients with choroidal melanoma. At the same time, there are practically no studies aimed at establishing the dependence of the frequency and severity of SRS complications on the initial characteristics of the tumor and dose parameters of radiosurgery. The aim of this study was to analyze the incidence of post-radiation complications, as well as the relationship between the clinical characteristics of the tumor and the dosimetric parameters of stereotactic radiosurgery and secondary glaucoma. Material and methods. The prospective study included 43 patients with cT1-3N0M0 choroidal melanoma. The median prescribed dose per tumor margin at 50% isodose was 30 Gy, (23-35 Gy). The immediate effect of the treatment was assessed as positive in all the cases, except for increased blood flow according to Doppler ultrasound data, an increase in tumor size by more than 20% of the previously determined lesion according to MRI. Univariate and multivariate regression analyzes were performed using the Cox proportional hazards model, ROC analysis for statistically significant variables. Results. During the follow-up period (median was 16 months), an objective tumor response to treatment was recorded in 100% of cases. Secondary cataract after SRS developed in 4 (9.3%) cases, post-radiation retinopathy - in 9 (20.9%) cases, secondary retinal detachment - in 7 (16.3%) cases, secondary glaucoma - in 6 (14%) cases. After SRS during the observation period, the eyeball was preserved in 90.7% of patients. For the tumor volume parameter, the area under the curve was 0.92 (95% CI 0.84-1.00) with a cut-off point of 800 mm3. With a tumor volume less than this indicator, no cases of secondary glaucoma were detected. In the case of tumors with a volume equal to or greater than the calculated value, secondary glaucoma developed in 71% of cases. For the tumor thickness parameter, the area under the curve was 0.78 (95% CI 0.63-0.93) with a cut-off point of 7.6 mm. With a tumor thickness of less than 7.6 mm, the incidence of secondary glaucoma was 5% during the observation period, with a tumor thickness greater than this indicator - 72%. Conclusion. In the treatment of tumors with a volume of more than or equal to 800 mm3 and/or a thickness of more than or equal to 7.6 mm, radiosurgery as a monomethod is not recommended; it is necessary to resort to a combined method, including, along with SRS, tumor endoresection.