Re: Short Telomere Length, Cancer Survival, and Cancer Risk in 47 102 Individuals

Extract

In a recent article, Dr Weischer and colleagues evaluated the association of peripheral leukocyte telomere length (TL) with cancer risk and cancer survival in 47102 Danish participants ( 1 ). Participants were followed for up to 20 years (median = 6 years), during which time 3142 individuals developed a first cancer, and of these, 1730 died. They concluded that “short telomere length is associated with reduced survival after cancer but not with cancer risk.”

This excellent study has many strengths, including large sample size, prospective and population-based study design, long-term follow-up, and precise assay technique. However, we have reservations about the conclusion that short TL was not associated with cancer risk. We propose that the data actually support the association of TL with cancer risks in a cancer site–specific manner: in some cancers, short TL confers increased risk, whereas in others, short TL confers reduced risk ( 1 ). When pooling data for all the cancer sites, the opposite associations cancel each other out, resulting in the null finding. For cancers of different etiology and risk factors, it is more prudent to analyze them separately.