Abstract
Purpose: :
To analyze the regression rate of posterior uveal melanoma following iodine-125 (I-125) plaque radiotherapy, and evaluate the predictive factors for tumor regression rate as well as the correlation of the regression rate with metastasis.
Methods: :
The clinical records of 95 patients with uveal melanomas treated with I-125 plaque radiotherapy at the Kellogg Eye Center between 1996-2006 and had more than three years of follow up were retrospectively reviewed. Data collected included gender, age, tumor location, ciliary body involvement, growth pattern, tumor thickness before treatment and at every 4 to 6 months follow-up, tumor recurrence and development of metastasis. A mixed linear regression statistical model was used to analyze the data.
Results: :
Following iodine-125 plaque radiotherapy, regression of posterior uveal melanoma followed a hyperbolic curve. For every 50% increase in follow-up time, tumors less than 3 mm in thickness showed 0.30 mm decreases in thickness, while tumors between 3 and 8 mm showed 0.57 mm decreases in thickness, and tumors thicker than 8 mm showed 0.99 mm decreases in thickness (p <0.0001). Superior tumor location was a statistically significant predictor of tumor regression rate [tumors in the superior location had an initial thickness on average 1mm larger than those located in the nasal region (p=0.0032)]. Patients who develop metastasis had faster tumor regression rates than patients who did not develop metastasis (P<0.01). Additionally, the patients who develop metastasis had a larger tumor thickness than patients who did not develop metastasis.
Conclusions: :
Regression rates are significantly faster for large uveal melanomas than medium and small melanomas. Tumors that developed metastasis showed faster regression rates and were larger than ones that did not. Superior tumors were significantly larger than nasal tumors.
Keywords: tumors • melanoma