Abstract
Background: Biofluids collected in a non-invasive fashion are potentially valuable samples for assaying genomic alterations for early detection and monitoring of cancer. The low cellularity and nucleic acid content in biofluids, the high copy number of the mitochondrial genome (mtgenome) and its noted early imprints in cancer make this molecule theoretically more sensitive than nuclear targets to measure for early cancer detection. Objective: This review explores mtgenome analysis in biofluids and addresses the question of whether targeting the mtgenome in biofluids is superior or equivalent to analysis of nuclear genomic alterations. Methods: The literature was retrieved from PubMed using a combination of the following keywords: mtDNA, mutation, deletion, content, copy number, cancer, biofluids, bodily fluids and the specific cancers described here. Studies that analyzed mtgenome alterations in biofluids were included. Analytical methods available for assaying mtgenome changes in biofluids are discussed. Results: Despite the limited data available, mtgenome changes in biofluids have been demonstrated in a wide variety of cancer patients. Conclusion: Mtgenome analysis in biofluids is feasible and relatively easy. Despite the paucity of data, tumor-specific mtgenome changes are observed in biofluids of cancer patients. Given the multiple copies per cell of the mtgenome, future cancer detection efforts should consider complementary analysis of mtgenome changes in biofluids.
Acknowledgements
Thanks to C Karwinski for editorial assistance and the anonymous reviewers for their comments on the manuscript.