Genetic alterations play a role in the growth of all types of cancer, and ... DNA is made up of combinations of four che
EMERGING ISSUES BRIEF Together-Eliminating Cancer
Precision Medicine: How Genetic Sequencing is Changing Cancer Care By Gregory J. Tsongalis, PhD, professor and director of Molecular Pathology at Norris Cotton Cancer Center; and Christopher I. Amos, PhD, associate director for Cancer Center Population Studies and head of the Center for Genomic Medicine at Norris Cotton Cancer Center.
or arrangement of the bases determines code units (referred
Genetic alterations play a role in the growth of all types of cancer, and researchers also have found that individual cancer
the exception of identical twins, the DNA of two individuals is different, and most of these differences are benign variations
Our genes differentiate us from other species, and from each other,
medicine” is used to describe how genetic information about a variations can consist of a change in a single base or alterations in Advances in the analysis of cancer tumors and the technology used for DNA sequencing now allow researchers to create
The first DNA sequencing
been developed that effectively target genetic differences in While only a few tumor types are currently known to respond
DNA sequencing, a process used to determine the exact order of
report the sequential order of bases in DNA (for which he and
What are genetic codes? Deoxyribonucleic acid or DNA (the molecules inside cells that carry genetic information and pass it from one generation to the made up of combinations of four chemical structures (known
allowed them to determine the sequence of bases in a DNA used by the Human Genome Project to map the human genome, a project that took ten years, many research-hours, and over a
reference sequence is now used routinely to identify benign and
Broader clinical applications for genetic sequencing
of bases in one DNA fragment, the process offered limited
50 genes known to be related to cancer, other clinical applications include testing for traditional genetic diseases and for common
progressed, and our recognition of the importance of the genetic contribution to human disease increased, it was clear that healthcare providers needed far more sequence information to
genome (with 3 billion bases) contains approximately 20,000 genes, only parts of the genome code for proteins that cells use
Next generation sequencing (NGS) Several new methods for DNA sequencing have been developed chemistries are similar to Sanger sequencing, new instruments use to perform millions of sequencing reactions simultaneously, is broken into small pieces, and each piece is labeled with a computer software is able to distinguish patients by these
to sequence a clinical exome of this size and, using this extensive panel, can provide clinicians with detailed information useful to managing patient care for most clinical scenarios, regardless of
The challenges of NGS: “incidental findings” and “difference of unknown significance”
is compared to sequences from healthy people to identify genetic
Genetic sequencing in cancer treatment
on a patient with a suspected genetic disease, sequencing the clinical exome may identify variations associated with conditions
with cancer: patients with colon cancer, brain tumors, melanoma, and lung cancer have been sequenced with a panel that reports on
should it be reported to the patient and/or family? Would the patient or relatives want to know information they were not seeking?
human cancers and contains those disease-related variants that are with NGS technologies, genetic variants not previously described will be benign, without any known (or even likely) clinical targeted because they make the tumor cells sensitive to therapy, and other mutations are targeted because they are known to
have established ethics committees and molecular tumor boards to address these issues and develop the working policies needed
Opportunities and unknown impact (such as monoclonal antibodies and tyrosine kinase inhibitors added to traditional cytotoxic chemotherapies) are shrinking
low-cost sequencing approaches can be applied to tumor samples
other instances, sequencing is helping to highlight where targeted on work at Dartmouth-Hitchcock that described mutations in study found that the types of mutations observed can identify the stages of appendiceal tumors, and these mutational observations can be used to identify targets for new therapies to effectively
NH Comprehensive Cancer Collaboration in partnership with DartmouthHitchcock Norris Cotton Cancer Center.
Together-Eliminating Cancer
August 2014
targeted therapies often respond dramatically to those therapies, but the vast majority of the differences between individual and
revolutionize our management of cancer patients, its appropriate
