Epidemiologic evidence for a role of telomere dysfunction in cancer etiology

► Telomere crisis implicated as a common crucial event in malignant transformation. ► Telomere length has emerged as a putative biomarker of cancer disease risk. ► Estimates from prospective studies are much weaker than from retrospective studies. ► Differences may be due to biases intrinsic to retrospective study design. ► Study design considerations are given for future investigations.