The later the median age at diagnosis, the greater the expression of
KIF14 (
P = 0.006). We compared the mean increase in
KIF14 with laterality, differentiation status, and invasion of the tumor, to understand why with later age at diagnosis tumors tend to have very high expression of
KIF14. However, we did not find any statistical significance between different subtypes. As
KIF14 probably has a role in cell proliferation and the severity of RB is related to the rate of proliferation of the tumor, even with known bias in patient’s history, the duration of the disease was calculated for individual patients and correlated with the relative
KIF14 expression. No significant variability in
KIF14 expression was noted with the increase or decrease in duration of the disease. As no correlation was found with laterality, invasion, differentiation status, and the duration, very high expression of
KIF14 in late-presenting patients may be due to the more predisposing genomic instability (possibly assisted by
KIF14) required for tumor progression in older patients than in patients with early-onset tumors.
4 A CGH study on 66 RB tumor samples showed more frequent and more complex abnormalities (median, five changes/abnormal tumor versus median, 1.5 changes/abnormal tumor;
P = 0.003) than RBs from children with a young age at enucleation.
6 In that study gains of all of 1q, 2p, 17q, of the entire chromosome 19, and losses of 16q were restricted to the older age group. These results suggest that the progression of RBs from older patients follows mutational pathways different from those of younger patients.