Metastatic melanoma death rates by anatomic site after proton beam irradiation for uveal melanoma

Background: Ciliary body location is an established prognostic factor for metastasis-related death from uveal melanoma. We evaluated alternative approaches for classifying this covariate when constructing predictive models of patient survival. Methods and Destgn: The analyses were based on a consecutive series of 1848 primary choroidal and/or ciliary body melanoma patients treated with proton beam irradiation (70 cobalt gray equivalent in 5 fractions) at the Harvard Cyclotron Laboratory, Boston, Mass, between July 1975 and December 1995. For each patient, the anatomic site of the tumor was classified according to an estimate of the proportion of the tumor base lying anterior to the ora serrata. Using proportional hazards regression, we estimated relative risk ratios and death rates from melanoma metastasis according to the extent of ciliary body involvement. All estimates were adjusted for other established prognostic factors. Results: Patients were followed up through April 30, 1998; none were lost to follow-up. Of 1848 patients analyzed, 378 died of melanoma metastasis. The median follow-up period among survivors was 9.5 years. Ciliary body origin (>50% of tumor base anterior to the ora serrata) was positively associated with tumor pigmentation (P<.001), tumor height (P<.001), and extrascleral extension of the tumor (P<.001). Compared with tumors involving only the choroid, melanoma-associated death rates increased with the proportion of the tumor base lying within the ciliary body (P=.006); the multivariate-adjusted relative risk ratio for greater than 75% involvement was 2.30 (95% confidence interval [CI], 1.26-4.23). The covariate-adjusted 5-year death rates for ciliary body origin and choroidal origin were 15.9% (95% CI, 11.3%-21.2%) and 9.8% (95% CI, 8.3%-11.7%), respectively. Conclusion: Patients with melanomas of presumed ciliary body origin seem to be subject to a higher risk of death resulting from melanoma metastasis.