Multicenter, International Assessment of the Eighth Edition of the American Joint Committee on Cancer Cancer Staging Manual for Conjunctival Melanoma.

This case series assesses whether the eighth edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual can be used to accurately estimate mortality rates of conjunctival melanoma. Key PointsQuestionCan the eighth edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual for conjunctival melanoma be used to accurately estimate metastasis and mortality rates? FindingsIn this case series of 288 patients, there was a significantly higher cumulative mortality rate among patients with cT2 and cT3 conjunctival melanoma compared with those presenting with cT1 conjunctival melanoma. MeaningHigher T-staged tumors were associated with both an earlier and greater incidence of metastasis; therefore, the results from this multicenter, international registry study support the use of the eighth edition AJCC staging system for conjunctival melanoma. ImportanceEye cancer staging systems used for standardizing patient care and research need to be validated. ObjectiveTo evaluate the accuracy of the eighth edition of the American Joint Committee on Cancer (AJCC) Cancer Staging Manual in estimating metastatis and mortality rates of conjunctival melanoma. Design, Setting, and ParticipantsThis international, multicenter, registry-based case series pooled data from 10 ophthalmic oncology centers from 9 countries on 4 continents. A total of 288 patients diagnosed with conjunctival melanoma from January 1, 2001, to December 31, 2013, were studied. Data analysis was performed from July 7, 2018, to September 11, 2018. InterventionsTreatments included excision biopsy, cryotherapy, topical chemotherapy, radiation therapy, enucleation, and exenteration. Main Outcomes and MeasuresMetastasis rates and 5-year and 10-year Kaplan-Meier mortality rates according to the clinical T categories and subcategories of the eighth edition of the AJCC Cancer Staging Manual. ResultsA total of 288 eyes from 288 patients (mean [SD] age, 59.7 [16.8] years; 147 [51.0%] male) with conjunctival melanoma were studied. Clinical primary tumors (cT) were staged at presentation as cT1 in 218 patients (75.7%), cT2 in 34 (11.8%), cT3 in 15 (5.2%), and cTx in 21 (7.3%). There were no T4 tumors. Pathological T categories (pT) were pTis in 43 patients (14.9%), pT1 in 169 (58.7%), pT2 in 33 (11.5%), pT3 in 12 (4.2%), and pTx in 31 (10.8%). Metastasis at presentation was seen in 5 patients (1.7%). Metastasis during follow-up developed in 24 patients (8.5%) after a median time of 4.3 years (interquartile range, 2.9-6.0 years). Of the 288 patients, 29 died (melanoma-related mortality, 10.1%) at a median time of 5.3 years (interquartile range, 1.8-7.0 years). The cumulative rates of mortality among patients with cT1 tumors were 0% at 1 year, 2.5% (95% CI, 0.7%-7.7%) at 5 years, and 15.2% (95% CI, 8.1%-27.4%) at 10 years of follow-up; among patients with cT2 tumors, 0% at 1 year, 28.6% (95% CI, 12.9%-58.4%) at 5 years, and 43.6% (95% CI, 19.6%-77.9%) at 10 years of follow-up; and among patients with cT3 tumors, 21.1% (95% CI, 8.1%-52.7%) at 1 year of follow-up and 31.6% (95% CI, 13.5%-64.9%) at 5 years of follow-up. Patients with cT2 and cT3 tumors had a significantly higher cumulative mortality rate compared with those presenting with cT1 tumors (log-rank P<.001). Patients with ulcerated melanomas had significantly higher risk of mortality (hazard ratio, 7.58; 95% CI, 1.02-56.32; P=.04). Conclusions and RelevanceThis multicenter, international, collaborative study yielded evidence that the conjunctival melanoma staging system in the eighth edition of the AJCC Cancer Staging Manual can be used to accurately estimate metastasis and mortality rates. These findings appear to support the use of AJCC staging as a tool for patient care and research.