As similar as the two terms may seem, there is a fundamental difference between genetics and genomics.
Understanding this difference also means understanding their implications in cancer care, from prevention to treatment. First, we have to differentiate the terms: genetics is a branch of biology that studies individual genes, genetic variation and heredity; whereas genomics is a more recent term for the study of the genome (an organism’s complete set of DNA, so all of its genes, as well as their interactions and influence).
Genomics and genetics : related to cancer
Now you may be thinking, how are these fields linked to cancer? Well, you first have to understand what cancer is: it is a group of diseases caused by abnormal cell growth that can spread to other parts of the body. In other words, cancer starts with a tumour (or neoplasm, an abnormal or excessive growth of tissue) which is a “mass” of cells whose growth is unregulated (the cells do not die normally, ignore signals to stop producing more cells and start encroaching on other biological processes).
The overwhelming majority of cancer originates from genetic mutations caused by environmental factors (with an estimated five to ten percent due to inherited genetics). So, studying genetics and genomics is key in understanding how cancer works and how to fight it (or prevent it, ideally).
And aside from cancer, a significant part of the leading causes of death in developed countries (such as heart disease, diabetes, Alzheimer’s disease, etc.) are influenced by genomic factors. While humans are 99.9% identical in their genetic makeup, the remaining 0.1% holds important information regarding causes of diseases. Understanding that last portion that makes up all the genetic differences in humans can yield crucial clues to combating some of the deadliest diseases our kind face.
How do we apply each to cancer research and therapy?
Genetics can study the variants in specific genes that can be inherited from parent to children and that can increase someone’s chance of developing cancer down the road. “Cancer genetics” is thus the study of those predispositions to developing certain types of cancer.
Those five to ten percent of “hereditary cancers” can be of the following types: prostate, melanoma, pancreatic, breast, ovarian, endometrial, colorectal, stomach or small bowel cancers. Taking into account a patient’s family history can thus give doctors even more information on how to predict their possible diseases and treat them.
On the other hand, genomics has a more holistic approach: while genetics mostly focus on how specific genes can cause specific cancer risks, genomics is also interested in how genes interact with each other and the environment (and thus, both discover new therapies and new ways of diagnosing patients).
And to go even further, the human genome is not the only subject; tumours also have their own genomic makeup which can be studied to both better understand how each kind appears and develops but also how to personalise each patient’s treatment. Indeed, some mutations can confer tumours resistance to certain drugs, and vice-versa, others can be susceptible to specific medications; understanding tumours’ genomic makeup thus makes it possible to understand their response to drugs.
In the same vein, oncology is not the only domain where genomics is applicable: genomic medicine can have applications in pharmacology, rare and undiagnosed diseases and infectious diseases. This is a facet of personalised or precision medicine, which aims to use information about a patient’s genome and environment on top of the more “traditional” data that has been used up until now.
What are some of the techniques and technologies derived from these fields?
Proteomics takes the same approach as genomics to study the DNA sequence of genes (which carry the instructions for building proteins in a molecule called the RNA) to study all the body’s proteins. This field can help identify which specific abnormal proteins can lead to diseases (such as some cancers).
Pharmacogenetics and pharmacogenomics are related and very close terms that are both concerned with determining a patient’s response to specific drugs. But more specifically, just like the difference between genetics and genomics, pharmacogenetics studies the variability of drug response due to the variation in single genes (thus allowing for personalised therapy); while pharmacogenomics studies the variation in multiple genes.
Pharmacogenomics can also be concerned with variations on population scale, to see how drugs might affect different groups. Both these fields allow for more personalised medicine depending on genetic makeup and environment (and the interactions between both).
Stem cells can also be considered a related field, as their stem cell “status” is due to the genetic code they contain. Stem cell therapy is thus yet another application of our better understanding of human genetics and genome.
To go even further, cloning may yet be another application of these fields: a clone is technically a genetic “double”. Therefore, in the case of cells, any cell that is the exact same as another cell can be considered “a clone”. Therapeutic cloning is the process of growing cloned cells or tissues from an individual (most often from stem cells) which we could use in regenerative medicine down the line (think growing back missing or damaged tissue to implant into a patient’s body).
To conclude, both these fields are extremely important to the future of medicine, as the promises they hold could tremendously improve the state of modern medicine. The possible applications of information gained from deeper understanding of singular genes’ effects can be multiplied and improved by a better understanding of the entire genome.
Among those applications are earlier diagnostics (tackling a disease earlier or even predicting its onset is always better, even if it does not always lead to a better outcome, especially if it is a disease we know little about), earlier interventions (with better hopes of curing it altogether) and targeted treatment (not only the aforementioned “personalised medicine” but also just identifying the patient’s ills more precisely to determine which treatment would be most efficient for them).
