Conjunctival melanoma treatment outcomes in 288 patients: a multicentre international data-sharing study

Background To relate conjunctival melanoma characteristics to local control. Methods Retrospective, registry-based interventional study with data gathered from 10 ophthalmic oncology centres from 9 countries on 4 continents. Conjunctival melanoma patients diagnosed between January 2001 and December 2013 were enrolled in the study. Primary treatments included local excision, excision with cryotherapy and exenteration. Adjuvant treatments included topical chemotherapy, brachytherapy, proton and external beam radiotherapy (EBRT). Cumulative 5-year and 10-year Kaplan-Meier local recurrence rates were related to clinical and pathological T-categories of the eighth edition of the American Joint Committee on Cancer (AJCC) staging system. Results 288 patients had a mean initial age of 59.7 +/- 16.8 years. Clinical T-categories (cT) were cT1 (n=218,75.7%), cT2 (n=34, 11.8%), cT3 (n=15, 5.2%), cTx (n=21,7.3%) with no cT4. Primary treatment included local excision (n=161/288, 55.9%) followed by excision biopsy with cryotherapy (n=108/288, 37.5%) and exenteration (n=5/288, 1.7%). Adjuvant therapies included topical mitomycin (n=107/288, 37.1%), plaque-brachytherapy (n=55/288, 19.1%), proton-beam (n=36/288, 13.5%), topical interferon (n=20/288, 6.9%) and EBRT (n=15/288, 5.2%). Secondary exenteration was performed (n=11/283, 3.9%). Local recurrence was noted in 19.1% (median=3.6 years). Cumulative local recurrence was 5.4% (3.2-8.9%), 19.3% (14.4-25.5%) and 36.9% (26.5-49.9%) at 1, 5 and 10 years, respectively. cT3 and cT2 tumors were twice as likely to recur than cT1 tumours, but only cT3 had statistically significantly greater risk of local recurrence than T1 (p=0.013). Factors such as tumour ulceration, plica or caruncle involvement and tumour thickness were not significantly associated with an increased risk of local recurrence. Conclusion This multicentre international study showed that eighth edition of AJCC tumour staging was related to the risk of local recurrence of conjunctival melanoma after treatment. The 10-year cumulative local recurrence remains high despite current management.