The latest British study on Intratumor Heterogeneity and Branched Evolution Revealed by Multiregion Sequencing may hinder personalized medicine strategies that depend on results from single tumor biopsy samples.
A reply to a Dr. Robert Nagourney blog posting about this study, brought up the Oncotype DX assay. The woman's breast tumor was early stage 1/grade 1 NO ER/PR positive Her2 negative and her Oncotype DX showed 8% recurrence rate.
After reading her pathology report, three years ago, she raised the question as to why the whole tumor was not looked at after the lumpectomy to make sure the diangosis was the same throughout the tumor. She was told it would be to lengthy, costly and she had nothing to worry about. She was told that they only test a slice of the tumor and throw the rest away. She was taken back by the oncologist's comment. Indeed, so would I.
After she read an article on the British study, is she to assume she may have been right? Or was the pathologist correct in telling her with his assessment of her tumor coupled with the Oncotype DX that things looked good for her and she was not on the Titanic. She was very depressed for someone who was three years out and wondering whether or not the treatment she received was really what she needed.
Indeed, intratumor heterogeneity can lead to underestimation of the tumor genomic landscape portrayed from single tumor-biopsy samples and may present major challenges to personalized medicine and genetic biomarker development. Intratumor heterogeneity, associated with heterogeneous protein function, may foster tumor adaptation and therapeutic failure.
The study is significant because it suggests relying on one sample could overlook important genetic biomarkers that help make tailored treatments effective, explaining perhaps why personalized cancer therapy has been less successful than expected. This does refer to genetic testing and not to functional profiling.
Intratumor Heterogeneity and Branched Evolution Revealed by Multiregion Sequencing
http://cancerfocus.org/forum/showthread.php?t=3640
Greg