Early ultrasonographic tumor regression after linear accelerator stereotactic fractionated photon radiotherapy of choroidal melanoma as a predictor for metastatic spread

Prognosis Prediction of Uveal Melanoma After Plaque Brachytherapy Based on Ultrasound With Machine Learning

INTRODUCTION

Uveal melanoma (UM) is the most common intraocular malignancy in adults. Plaque brachytherapy remains the dominant eyeball-conserving therapy for UM. Tumor regression in UM after plaque brachytherapy has been reported as a valuable prognostic factor. The present study aimed to develop an accurate machine-learning model to predict the 4-year risk of metastasis and death in UM based on ocular ultrasound data.

MATERIAL AND METHODS

A total of 454 patients with UM were enrolled in this retrospective, single-center study. All patients were followed up for at least 4 years after plaque brachytherapy and underwent ophthalmologic evaluations before the therapy. B-scan ultrasonography was used to measure the basal diameters and thickness of tumors preoperatively and postoperatively. Random Forest (RF) algorithm was used to construct two prediction models: whether a patient will survive for more than 4 years and whether the tumor will develop metastasis within 4 years after treatment.

RESULTS

Our predictive model achieved an area under the receiver operating characteristic curve (AUC) of 0.708 for predicting death using only a one-time follow-up record. Including the data from two additional follow-ups increased the AUC of the model to 0.883. We attained AUCs of 0.730 and 0.846 with data from one and three-time follow-up, respectively, for predicting metastasis. The model found that the amount of postoperative follow-up data significantly improved death and metastasis prediction accuracy. Furthermore, we divided tumor treatment response into four patterns. The D(decrease)/S(stable) patterns are associated with a significantly better prognosis than the I(increase)/O(other) patterns.

CONCLUSIONS

The present study developed an RF model to predict the risk of metastasis and death from UM within 4 years based on ultrasound follow-up records following plaque brachytherapy. We intend to further validate our model in prospective datasets, enabling us to implement timely and efficient treatments.

Regression rate of choroidal melanoma following iodine-125 brachytherapy is not associated with metastatic spread

Nearly half of choroidal melanomas progress to the metastatic stage at 15 years. The purpose of our study was to evaluate the prognostic value of tumour-height regression rate in medium-sized choroidal melanomas treated with iodine-125 brachytherapy. A retrospective cohort study was performed on 128 patients with medium-sized choroidal melanoma who were treated with iodine-125 brachytherapy. Tumour characteristics including tumour apical height at baseline and after irradiation, recurrence, metastasis and mortality were collected from patients' records. Regression rate was defined in mm/month or in percentage of baseline apical height. Patients were statistically stratified in three groups of regression rate at 6 months using the Ward's method and Euclidian distance (slow, medium and fast regression groups). Mean initial apical height was of 5.71±1.79 mm. At 6 months, the average regression rate was 0.02±0.12 mm/month in the slow group (n=60), 0.32±0.11 mm/month in the medium group (n=52) and 0.67±0.21 mm/month in the fast group (n=16). Cox regression analysis for the recurrence, metastasis and mortality rates according to the three groups did not show any statistically significant difference. Sensitivity analyses with the regression rates at 12 months showed similar associations. Exudative retinal detachment resolved with treatment at 5.9±4.0 months, and it was more common at presentation in the fast regression rate group. The regression rate at 6 and 12 months after iodine-125 brachytherapy is not associated with a higher metastatic rate in medium-sized choroidal melanoma.