Staging of Ciliary Body and Choroidal Melanomas Based on Anatomic Extent

Abstract

To refine the anatomic classification and staging of ciliary body and choroidal melanomas in the TNM classification. Tumor largest basal diameter and thickness of 7,369 patients were analyzed based on registry data from five ocular oncology centers. T categories were derived empirically by dividing data into blocks representing 3- × 3-mm fractions. Blocks with similar survival were grouped together so that no T category comprised a large majority of tumors, and each was uniform in survival, using randomly drawn 60% building and 40% validation data sets. Presence of ciliary body involvement (CBI) and extraocular extension (EXE) was analyzed among 5,403 patients to define T subcategories. Stages were generated by iteratively combining subcategories with similar survival. Of the 7,369 tumors analyzed, 24% were classified as T1, 33% as T2, 31% as T3, and 12% as T4. Ten-year Kaplan-Meier survival estimates for the T categories were 89%, 77%, 58%, and 39%, respectively (P < .001). Survival of patients in four subcategories based on presence or absence of CBI and EXE differed significantly within each T category (P = .018 for T1; P < .001 for T2 to T4). EXE exceeding 5 mm in largest diameter carried a worse prognosis than smaller extensions (P < .001) and was assigned a separate subcategory. Ten-year Kaplan-Meier survival estimates for stages I, IIA to IIB, and IIIA to IIIC were 88%, 80%, 67%, 45%, 27%, 10%, respectively (P < .001). This evidence-based anatomic classification provides a basis for staging ciliary body and choroidal melanomas in the seventh edition of the Cancer Staging Manual of the American Joint Committee on Cancer.