Why are cancer, rare diseases and infectious diseases the principle targets of the 100,000 Genomes Project?
Is cancer genetic or inherited?
How can cancer be inherited?
What are the approaches involved in managing familial cancer?
What test does cancer genomics principally involve?
What three other approaches are also used?
Why are cancer, rare diseases and infectious diseases the principle targets of the 100,000 Genomes Project?
In February 2015 it was announced that an estimated 50% of Britons will get some form of cancer at some stage in their lives. Also three million people, half of them children, suffer from rare diseases. Genome sequencing is a new technology, which we want to use to maximize medical insights alongside new scientific discoveries as early on as possible. We want to understand how genomics influences diseases and how it can be applied within a healthcare setting.
Is cancer genetic or inherited?
Cancer is not purely a case of cells dividing too fast; it is caused by the loss of control of the balance between cell growth, cell maturity (called differentiation) and cell death. As a result it is usually due to the accumulation of changes (mutations) in a number of different types of genes involved in regulating the division of cells. The vast majority of these gene changes are not inherited and approximately 10% overall have a strong inherited component. This involves mistakes in processes such as cells growing, cells dividing, cell death, repair of DNA damage, development of own blood supply, ability to invade and attach to new tissues.
How can cancer be inherited?
Up to 20,000 different mutations can be present within the tumour. The vast majority of these are not inherited and therefore cancer can be described as a genetic condition but only 5-10% is inherited. Occasionally an inherited alteration in a gene can greatly increase the risk of cancer. As we have two copies of each of our genes and pass one on to each of our children, the risk of passing on the gene change to any child is 50%. Without intervention, the risk of cancer in these situations can be over 80%. A tumour is more likely to be inherited if it occurs at a young age or if there is already a family or personal history of the same or related tumours. Overall 5-10% of patients with cancer have a single high-risk gene alteration and this equates to about 1% of the population.
What related tumours should you be aware of?
- Breast, ovarian or prostate cancer
- Stomach and breast cancer
- Melanoma and pancreatic cancer
- Stomach, bowel and gynaecological cancer
- Kidney and nervous system
- Any combination of hormonal gland tumours
- Breast, thyroid and womb cancer
What are the approaches involved in managing familial cancer?
- Taking a personal and family history of symptoms and cancer
- Determining if genetic or genomic testing is indicated, which is usually possible if the likelihood of identifying a significant gene alteration is calculated to be at least 10%
- Using empirical evidence and results to calculate future risk
- Offering risk reducing strategies, which may involve lifestyle changes, medication (often offered at 4% ten year risk) or surgical options (often offered at 10% ten year risk)
- Offering advice on early detection and screening (usually offered at more than 3% ten year risk)
- Framing advice within context of personal experience and cultural background to ensure patient is supported through their cancer journey, both within the healthcare department and in providing opportunities to take part in research and link with stakeholder groups.
What test does cancer genomics principally involve?
Carrying out a blood test to look at the 100 genes that have been associated with an increased risk of inherited cancer.
What three other approaches are also used?
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- Assessing the tumour to identify new non-inherited mutations in the DNA code that might be driving the tumour and may make the tumour vulnerable to specific targeted therapies
- Identifying circulating free DNA in the blood, which had been released into the bloodstream that can help with decision-making around timing of or need for chemotherapy
- In time looking for patterns in the DNA of tumours or blood from cancer patients to identify common patterns that may tell us more about the causes of cancer or help predict response to treatments.
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