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.