A confirming review of studies: "Telomeres play a key role in the maintenance of chromosome integrity and stability, and telomere shortening is involved in initiation and progression of malignancies. A series of epidemiological studies have examined the association between shortened telomeres and risk of cancers, but the findings remain conflicting. ... A dataset composed of 11,255 cases and 13,101 controls from 21 publications was included in a meta-analysis to evaluate the association between overall cancer risk or cancer-specific risk and the relative telomere length. ... The results showed that shorter telomeres were significantly associated with cancer risk compared with longer telomeres. ... Studies have showed that telomeres are critical for maintaining genomic integrity and that telomere dysfunction or shortening is an early, common genetic alteration acquired in the multistep process of malignant transformation. In addition, telomere dysfunction has been found to be associated with decreased DNA repair capacity and complex [cellular] abnormalities. Both of animal studies and clinical observations have shown that shorter telomeres were associated with increased risk of cancers, such as epithelial cancers. However, telomere shortening might play conflicting roles in cancer development. For example, the progressive loss of telomeric repeats with each cell division can induce replicative senescence and limit the proliferative potential of a cell, thus functioning as a tumor suppressor. But, once telomeres reach a critical length, it will result in chromosome break, causing genome instability and enhancing potential for malignant transformation."

Link: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC3112149/