Background Largest basal diameter (LBD) appears to have independent prognostic value in uveal melanoma (UM).
Methods All patients undergoing plaque brachytherapy or enucleation for UM involving the choroid and/or ciliary body between 2012 and 2019.
Results A total of 348 patients with a mean age of 60±14 years were included and followed for a mean of 40±26 months (3.3±2.2 years). On multivariate analysis, LBD >12 mm remained a significant independent predictor of metastasis for both class 1 (HR 21.90; 95% CI 2.69 to 178.02; p=0.004) and class 2 (HR 2.45; 95% CI, 1.03 to 5.83; p=0.04) tumours. Four prognostic groups were created: group 1 (class 1, LBD <12 mm), group 2 (class 1, LBD ≥12 mm), group 3 (class 2, LBD <12 mm) and group 4 (class 2, LBD ≥12 mm). Life tables were used to calculate the 3-year and 5-year metastasis-free survival: group 1 (98 and 98%), group 2 (86 and 86%), group 3 (81 and 62%) and group 4 (54 and 47%). Compared with the reference category (group 1), the Cox proportional hazard model demonstrated a significant worsening of survival for each progressive category (group 2 (HR 21.59; p=0.004), group 3 (HR 47.12, p<0.001), and group 4 (HR 114.24; p<0.001)). In our dataset, the four-category Cox model performed poorer compared with the American Joint Committee on Cancer (AJCC) and gene expression profile (AJCC+GEP) in the Akaike’s information criteria (AIC) (297 vs 291), fit better with the Bayesian information criteria (BIC) (309 vs 313) and performed similarly with the Harrel’s C (0.86 (95% CI 0.80 to 0.91) vs 0.89 (0.84 to 0.94), respectively).
Conclusions Combination of GEP and LBD allows separation of patients into four easy-to-use prognostic groups and was similar to a model combining AJCC stage with GEP.
Statistics from Altmetric.com
Contributors All authors have contributed to study design (KAR, EW), data collection (KAR, PG, SL), data analysis (EW), drafting (KAR) and revision (KAR, PG, SL, EW) of the manuscript.
Funding The authors have not declared a specific grant for this research from any funding agency in the public, commercial or not-for-profit sectors.
Competing interests None declared.
Patient consent for publication Not required.
Ethics approval The Health Research Ethics Board of Alberta – Cancer Committee approved this study. Ethics ID HREBA.CC-17-0625.
Data availability statement No data are available.
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