24 July 2015
Genetic variants play a significant role in common diseases, especially cancer. Yet evidence for the inclusion of genetic profiling in population health screening and prevention programmes has been weak, and risk assessment currently tends to focus solely on age, sex, family history and certain lifestyle factors (for example, smoking).
In the last few years, there has been a dramatic shift in the evidence base in support of the potential utility of genomic information in common disease prevention. Numerous common genetic variants have been linked to the risk of developing specific cancers, including 86 ‘susceptibility variants’ for breast cancer and more than 100 for prostate cancer.
Using genetic information to refine risk for screening
Though the effect of an individual common genetic susceptibility variant on the risk of disease is generally moderate, the presence of multiple variants influencing the same complex disease appear to have cumulative effects; for example, increasing the risk of prostate cancer risk by as much as 5-fold. Including this ‘polygenic’ (derived from knowledge about variants in multiple genes) information in established risk prediction models can improve the accuracy of risk prediction.
Compared to the standard age-based breast cancer screening, ‘risk-stratified screening’ that uses polygenic information as well as age could detect almost the same number of breast cancer cases whilst screening fewer women. This is desirable, because potential harms are associated with screening, notably the phenomenon of overdiagnosis (diagnosing and treating breast cancers that, if undetected, would not have shown any clinical progression in the woman’s lifetime).
Additionally, there are ongoing population studies that aim to explore the effectiveness and feasibility of risk-stratified prev ention (for example see Howell et al. 2012). Overall, the picture suggests growing evidence to support the inclusion of genetic profiling as part of population disease prevention in some shape or form within the healthcare system. However, successful implementation relies on the preparedness of the health system, including the people working on the frontline to deliver these programmes. Are primary care health professionals e quipped to use genetic information in risk-stratified prevention?
Assessing the competences gap
The potential ability to calculate disease risk more accurately in an asymptomatic individual (who may not have family history of the condition in question) is exciting. It offers the prospect of stratifying populations to identify those people at greatest risk much more accurately, allowing the offer of personalised interventions such as more frequent screening tests. Those at lower risk could receive general advice rather than active screening.
Through its role in the multicentre European research, Collaborative Oncological Gene-environment study (COGS), the PHG Foundation has been pioneering exploration of the implications of integrating genetic profiling into established screening programmes. Several papers emerging from this work have been published in the medical media, including most recently in the Journal of Personalized Medicine, where we argued that in order to implement genetic profiling in stratified prevention, clarity is needed on the implications for skills development among relevant health professionals.
Although preliminary investigation suggests that knowledge and skills gaps are not extensive, we recommended that a formal education and training needs assessment should be conducted to establish the current baseline position, and then plan appropriate changes. This will allow timely preparation of the health work-force as an essential component towards successful implementation of genomics into 21st century healthcare – and a matter for consideration by the Health Education England Genomics Education Programme as well as professional groups.
You can read the full paper, Do Health Professionals Need Additional Competencies for Stratified Cancer Prevention Based on Genetic Risk Profiling? here