Positive correlation between telomere length and mitochondrial copy number in breast cancers

We read with great interest the article published by Campa et al. (1) about mitochondrial DNA (mtDNA) copy and telomere length (TL) in breast cancer. It suggested that telomere elongation and mitochondrial instability contribute to the carcinogenesis in breast cancer. TL and mtDNA copy number have been considered as important factor to cancer progression in various cancers. And their correlation in normal tissues and cancers also has been observed by several authors (2,3). However, Campa et al. (1) did not present the correlation between TL and mtDNA copy number in breast cancer. Recently, we are studying clinical and prognostic values of TL and mtDNA copy number in breast cancers, therefore, their association was analyzed.