Although it is widely recognized that telomere dysfunction plays an important role in cancer, the relationship between
telomere function and bladder cancer risk is not well defined. In a case–control study of bladder cancer in Egypt, we
examined relationships between two telomere features and bladder cancer risk. Telomere fluorescent in situ hybridization
was used to measure telomere features using short-term cultured blood lymphocytes. Logistic regression was used to
estimate the strength of association between telomere features and the risk of urothelial carcinoma of the bladder.
High telomere length variation (TLV) across all chromosomal ends was significantly associated with an increased risk of
bladder cancer [adjusted odds ratios (OR) = 2.22, 95% confidence interval (CI) = 1.48–3.35], as was long average telomere
length (OR = 3.19, 95% CI = 2.07, 4.91). Further, TLV and average telomere length jointly affected bladder cancer risk: when
comparing individuals with long telomere length and high TLV to those with short telomere length and low TLV, the
adjusted OR was 14.68 (95% CI: 6.74–31.98). These associations were stronger among individuals who are 60 years of age
or younger. In summary, long and heterogeneous telomere length in blood lymphocytes was strongly associated with an
increased bladder cancer risk in Egyptian and the association was modulated by age.