Precision Medicine: The Road to Customized Healthcare
By Nikoo Dalili and Bianca Nguyen
If you have ever taken a genetics class, read an article about the future of healthcare, or seen an advertisement for a new drug therapy, you may have come across terms such as individualized medicine, personalized medicine, and precision medicine. You may have even seen them used interchangeably.
What do these terms really mean and is there a difference between them? This is a good question: there does not appear to be any standardization in the language employed by various research and publications in describing the specifics of genomic research and medicine. Clarifying these terms will allow us to explore the different implications this field has for human health in the coming decades.
According to the National Research Council, “personalized medicine” is an older form of the more novel term “precision medicine”. [1] The former should be phased out in substitution for the latter, as “personalized medicine” implies that treatments and interventions can be specially tailored for each individual. Precision medicine is not a wholly individualized approach, but is useful for identifying effective treatments for patients based on their genes, lifestyle, and environment. [1] Thus, subsets of patients sharing similarities in these categories may receive more targeted treatments for their ailments. This assures that initial prescriptions will be effective with minimal side effects, which reduces time and healthcare costs, and further encourages the patient to adhere to their treatments. [1]
While this provides understanding for when both “precision” and “personalized” are used interchangeably, some researchers intentionally use “personalized” or “individualized medicine” to refer to tailoring treatment based on an individual’s own, unique genome and circumstances. [2] It is therefore important to use context in understanding intended meanings of authors throughout literature.
Both genes and environmental factors affect one’s overall wellbeing and health. One of the major areas in which precision medicine has made breakthroughs is disease genomics. Disease genomics is a subcategory of precision medicine that includes Cancer Genomics. Cancer is a genetic disease that affects millions of people around the world. Oncogenetic or cancerous growth begins when one cell loses control over its own growth and escapes death by evading the immune system. In this manner, it continues to accumulate mutations in the genome of its progeny that make these cells grow even faster. These cells use up the body’s precious resources such as glucose and oxygen, and eventually, it reaches the point where cancerous cells form a significantly sized mass of cells known as a tumor that can be detected using x-ray technology by a physician. [3]
Scientists in genomics and precision medicine realize that there are different ways in which cancer affects human beings. From the detection and prevention of cancer, precision medicine can play a great role. Firstly, diseases can be prevented using gene sequencing. For example, variations of BRCA1/2 have an 80% chance of developing into breast cancer and also a 60% chance of developing into ovarian cancer; the early detection of these genes can not only allow the individual to engage in preventative surgeries such as a double mastectomy (removal of both breasts) and oophorectomy (removal of ovaries), but also early interventions such as chemotherapy in the future if the situation arises. [4]
This is especially important when dealing with conditions such as cancer because the stages can progress rapidly, without the knowledge of the individual. Cancer treatment is in itself further complicated by the fact that one medicine that works for someone might not work for other people. This is why scientists are using new ways to understand cancer origins, progression, and determine which altered genes need to be investigated to develop appropriate drug target mechanisms. Precision medicine has many benefits, especially pertaining to the first line treatment of cancer. After detection, precision medicine can come up with more effective treatments the first time around by thoroughly analyzing and conducting a genome analysis of the individual, which would not only lessen time in trying other medications, but would also reduce healthcare costs in the near future as well. [5]
Further exploring the field of precision medicine lies a new area of medicine called Personal Genomes, which includes pharmacogenomics. This relatively new field combines the principles of genomics and pharmacology to develop effective, safe medications and doses that are tailored to variations in a person’s genes. [6] Every individual has a different allele (type of gene), which results in genetic variation. Gene variations can affect one’s drug metabolism, which means that some people may breakdown certain medications either:
- too slowly, resulting in the medication build-up and consequently severe side effects.
- too quickly, and therefore eliminate it before it has a chance to work at effective levels.
The way to combat this issue in modern medicine is to rely on the tools and technology that pharmacogenomics provides. The in-depth analysis and study of the specific person’s genome will shed light on which medication is right, and has the lowest possible side effects for that individual. This genetic profile can make these predictions: whether a specific medication is likely to help you or hurt you before you even ingest it.
An example is the set of statins (i.e. cholesterol medications) that are used for lowering body cholesterol levels. Examples are atorvastatin, simvastatin, rosuvastatin, and pravastatin, which block the liver from making cholesterol. Unfortunately, for the 20% of the population that tries to take Atorvastatin, they have severe leg and body cramps as a side effect. The individual would have to go through a lot of these medications, testing and trying them out before finding the medication that would work for them, which prevents them from receiving proper treatment. This is where pharmacogenetics comes in: testing and analyzing how a statin might act on one’s body, as well as the dosage that would be required to get the best result, will help design the best plan for the patient, effectively increasing health outcomes. [7]
It is clear that precision medicine offers promising possibilities in eliminating disease and preserving the health of our future loved ones. But what are the current challenges and potential implications in pursuing this venture? Clinical and hospital databases will need to be designed to store much larger amounts of patient data, as information about patients’ genomes will need to be included. [8]
Additionally, designing more secure systems is necessary to safeguard this private, sensitive information. Extension of informed consent procedures is imperative, as it is extremely important patients understand the risk and benefits of releasing their genetic information. [8] One of the biggest concerns is that precision medicine will only be an option available to the most affluent of our society, widening the health disparities gap between the rich and poor; drugs targeting specific characteristics will inevitably become more expensive and will not be covered by insurance. [9] Lastly, doctors and other medical professionals will need to take on the additional responsibility to learn how to interpret genetic test results to provide relevant recommendations/treatments, as well as being able to translate this knowledge and share it with their patients. [8]
Among voices echoing these concerns is the public health community. Although acknowledging that precision medicine allows us to understand patterns of resistant strains of disease, classify disease for improved implementation of prevention strategies, and ensure treatments are effective while minimizing harm, commentators worry that its narrow focus on the genome detract from population-based public health interventions, which take into account environmental and social determinants of health. [10] Relying on genetic risk information may lead individuals to believe in ‘biological determinism’ — that the course of their disease cannot be altered by lifestyle and behavioral changes. More dangerously, this can lead to harmful, invasive interventions when failing to consult clinical data in tandem with genetic testing. [10]
Lastly, low-income minority groups, who are the most disproportionately affected by higher rates of disease, will likely not reap these benefits as additional genetic sequencing and specific therapies will warrant costs that are not covered by insurance. Further, ethnic minorities express higher levels of distrust of genetic services, which is a deterrent from precision medicine reaching these individuals even if they do have access. This distrust is likely a result of the long history of medical racism and research abuse enacted on marginalized racial groups.
Individuals of European descent are also overrepresented in genome studies, resulting in poor data and interventions that are not inclusive of minority groups. [10] Enrolling underserved communities in precision medicine research also requires awareness that these individuals do not have equal opportunities to take action on the medically relevant results they receive, and is another understandable barrier to their participation. [11] For precision medicine to serve the health of all, it is imperative to uphold population health as we collectively take steps to acknowledge and alleviate these aforementioned inequities.
Nikoo graduated from UCLA with a major in Neuroscience. Bianca is a fourth-year Human Biology Society major at UCLA. Nikoo and Bianca are both THINQ 2020–2021 clinical fellows.
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