Compare yourself with a stranger on the street and you could probably come up a long list of what make the two of you different: your skin colour, your height or even your personality. Although the two of you share 99.9 percent of the same DNA, the remaining 0.1 percent can clearly make a world of a difference.
Yet when it comes to healthcare, individual differences are often ignored in favour of treating the ‘average’ patient. Although doctors do take factors such as age, sex and family history into account, most patients with the same disease receive the same drugs, even if they may not ultimately benefit from it. The situation is particularly dire for conditions like Alzheimer’s disease, where 70 percent of patients do not respond to the medications available.
But what if doctors had more information at their disposal to make better recommendations to their patients? This is the goal of precision medicine, which aims to move away from a one-size-fits-all approach to provide targeted treatments. It not only considers a patient’s genetic background, but their lifestyle and environmental exposure as well, providing a much more holistic understanding of each patient and how he or she might respond.
Far from being a distant reality, precision medicine is actually already being practiced today, albeit in a limited way. For example, once a patient has been diagnosed with breast cancer, they are often offered a test to determine whether their cancer cells have certain markers, information that can help them identify which drugs would be the most effective for their specific type of cancer.
As scientists learn more about the genetic causes of a growing list of diseases, such tests will slowly become commonplace in the clinic, helping doctors chart the best course of treatment for their patients upon diagnosis instead of putting them through a trial-and-error process of figuring out the right drugs. By comparing each your DNA against sequences in large genetic databases, medical professionals will be more likely to find patients like you, and tailor your treatment based on what was found to be best for those patients.
Precision medicine could also be a matter of life or death for certain patients. Because they lack an enzyme to process a common amino acid, patients with phenylketonuria must avoid certain foods and artificial sweeteners or risk severe brain damage and even death. Just as the screening of newborns at birth has saved the lives of many people with phenylketonuria, precision medicine could also identify which patients might suffer severe side effects before the drugs are given, potentially averting disaster.
While precision medicine holds great promise for individual patients and their family members who may share the same genetic variants, its greatest impact may be at the population level instead. Not only do more effective treatments and fewer side effects reduce the overall burden on the healthcare system, but the ability to identify patients at risk of disease allows doctors to focus on prevention rather than cure. This is because conditions diagnosed when the disease is pronounced are much harder—and more costly—to treat, with no guarantee of success. For example, while diabetes can be managed at the early stage, patients that find out about their condition only when the symptoms are severe could face heart disease, stroke or even the loss of limbs.
Although there is the misperception that precision medicine is expensive and only serves to drive patients to unaffordable tests and treatments, the reverse is true. In a recent study of biomarker-based screening for gastric cancer, researchers found that screening was cost-effective for Chinese men aged 50 to 75, largely because they are four times more likely to have gastric cancer than the general population. In the case of other diseases, such as diabetes or heart disease, other ethnic groups are more at risk and would benefit from screening. Thus, when used for those who need it the most, precision medicine can help make good use of finite healthcare budgets.
In fact, responsibly and carefully considered applications of precision medicine could mitigate Singapore’s rising healthcare expenditures in the face of challenges like an ageing population and the attendant surge of chronic diseases. Empowered with information about their genetic susceptibility to disease, patients can take targeted prevention and health promotion measures, while those who receive diagnoses can expect more personalised treatments and a lower risk of adverse drug reactions.
The true power of precision medicine, however, is that it will provide a deeper understanding of ourselves and what goes wrong in the context of disease. The genetic, lifestyle and environmental data collected will shed light on the causes of disease and what can be done to avoid or ameliorate them. Importantly, this understanding will lead to better ways of diagnosing different diseases and the development of urgently needed new treatments.