A reappraisal of the significance of largest basal diameter of posterior uveal melanoma

Objectives To evaluate the significance of the largest tumour diameter (LTD) of posterior uveal melanomas (ie, involving choroid), correlating this feature with histological and cytogenetic predictors and mortality. Methods Patients with posterior uveal melanoma were included. LTD was measured by echography and correlated with histological and cytogenetic findings and metastatic death. Results The cohort comprised 1776 patients with a median age of 60 years, a median tumour diameter of 14.0 mm, and a median tumour height of 7.5 mm. The LTD was greater in older patients (t-test, P<0.001). The presence of epithelioid cells, closed loops, high mitotic rate, chromosome 3 deletion, and chromosome 8 gains all correlated significantly with LTD (t-test, P<0.001). The 1521 British patients had a median follow-up of 4.9 years, with a disease-specific mortality of 28.9%. Metastatic death correlated with LTD (Cox multivariate analysis, P<0.001). Tumours with the same LTD showed significant variation in survival, according to the presence of epithelioid cells (Log rank, P<0.001), closed loops (Log rank, P=0.002), high mitotic rate (Log rank, P=0.003), and chromosome 3 loss (Log rank, P=0.008). Conclusions The value of LTD as a predictor of survival after treatment of posterior uveal melanoma is enhanced by taking histological and cytogenetic factors into account. Eye (2009) 23, 2152-2162; doi:10.1038/eye.2009.235; published online 30 October 2009