Staging of ciliary body and choroidal melanomas based on anatomic extent

Abstract

Purpose: To refine the anatomic classification and staging of ciliary body and choroidal melanomas in the TNM classification. Patients and Methods: 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. Results: 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). Conclusion: 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.