The Case for Observational Management of Suspected Small Choroidal Melanoma

Abstract

I N DECEMBER 1997, THE ARCHIVES reported the outcome of the Collaborative Ocular Melanoma Study small tumor observational study documenting factors predictive of growth and treatment in this multicenter clinical trial. Accompanying that issue was an editorial that delineated the pros and cons to observation vs early treatment for small choroidal melanoma. In that editorial, an argument was made for a randomized clinical trial to definitively address the critical clinical question, “Do I treat now or do I wait?” Now approaching the latter half of a decade from this discussion, we as the ophthalmologists managing patients with suspected small choroidal melanomas are still faced with the dilemma as to the best treatment approach for these patients. Recent advances in clinical oncology and in ocular oncology have focused on delivering early, targeted, definitive therapy to primary malignancies. Cutaneous melanoma management has benefited from aggressive screening programs to identify suspicious lesions, to evaluate these lesions with new imaging techniques, and to excisionally manage atypical lesions to prevent progression and increased risk of tumor metastasis. The ease of identification and monitoring of cutaneous lesions has improved the early detection of stage I cutaneous melanoma and enhanced longterm survival. Recent histopathologic classification for cutaneous melanoma has noted significant decrease in mortality as a factor of tumor thickness. For cutaneous malignant melanoma undergoing excisional surgery, patient survival is 90% for lesions less than 0.76 mm in thickness, 79% for lesions 0.76 to 1.50 mm in thickness, and 62% for lesions 1.51 to 2.50 mm in thickness. Using this analysis, one could argue to remove all pigmented cutaneous lesions, but the significant caveat is that this study included only lesions undergoing excision and having malignant histopathology. Nonetheless, cutaneous melanoma differs significantly from ocular melanoma in its patterns of growth, vascularity, immunologic profile, sites for metastasis, and response to treatment. Ocular melanoma is clearly a distinct entity that requires independent evaluation as a unique tumor type. The National Eye Institute and National Cancer Institute (Bethesda, Md) devoted significant resources to the Collaborative Ocular Melanoma Study, targeting randomized evaluations for treatment of medium and large choroidal melanoma. These studies documented no benefit to pre-enucleation radiation therapy followed by enucleation for large choroidal melanoma and no benefit of enucleation relative to globeconserving brachytherapy in medium choroidal melanoma. Further, this study documented melanomaspecific 5-year mortality rates of 27% and 10%, respectively, for large and medium choroidal melanoma. The Collaborative Ocular Melanoma Study small tumor observational study included 204 patients with tumors between 1.0 and 3.0 mm in apical height and 5.0 and 16.0 mm in largest basal dimension. This observational study noted a 5-year documented tumor growth rate of 31% and a 5-year melanomaspecific mortality rate of 1.0% and defined features predictive of tumor growth to include larger tumor size, presence of orange pigment, absence of drusen, and absence of retinal pigment epithelium alterations adjacent to the small choroidal tumor. This observational study was devised to provide a framework for a small tumor randomized clinical trial to evaluate immediate vs deferred treatment for globe-conserving therapy. In the absence of clinical trials data, the clinician must use his or her best judgment from existing information, focusing on the best evidencebased data. Theophthalmologicmanagement ofsuspectedsmallchoroidalmelanoma isuniqueinseveralways,includingthe inability toadequatelyexciseatypical choroidal lesions, thevariationwithin thesesmall lesionsonhistopathologic review precluding effective nonexcisional biopsy, the potential for vision andglobecompromisewithdefinitive therapy(retinopathy,neuropathy),and the extremely low mortality rates associatedwiththemanagementofsmall choroidal malignant melanoma. The issueofmanaging these lesions is criticalbecauseapproximately10%of the population harbor 1 or more pigmented choroidal lesions (typically evaluatedwithinanon-Hispanicwhite population study). Several advances in the clinical management of intraocular lesions have come to the forefront over the last decade, including enhanced ocular imaging with digital photography(Panoret,Medibell,YoqneamIpit, Israel; RetCam, Clarity Medical SysAuthor Affiliations: Ocular Oncology Service, Bascom Palmer Eye Institute, University of Miami School of Medicine, Miami, Fla (Dr Murray); and Massachusetts Eye and Ear Infirmary, Boston (Dr Sobrin).