‘Carbon dating’ cancer? What’s that all about?

May 16, 2017 in In the News

Last week, the Institute of Cancer Research announced that scientists have been able to precisely pinpoint the timing in which different stages of a patient’s cancer developed. This could result in some interesting progress in the treatment and understanding of cancer and I will explain how researchers are doing this, but first- what is cancer?

Cancer is a group of diseases caused by the uncontrollable division of damaged cells. Cells can become damaged in this way due to a mutation in their DNA which intervenes with the regulation of mitosis (cell division). More specifically, the genes proto-oncogenes and tumour suppressor genes can become mutated. Proto-oncogenes trigger division, however mutated ones (known as oncogenes) trigger mitosis to happen at a much faster rate than normal. Meanwhile, mutated tumour suppressor genes fail to inhibit cell division as they should. Both mutations, as you can imagine, lead to the fast and furious growth of a cell into a tumour.

Mutations naturally occur quite frequently, but not all mutations cause cancer, and in fact it often requires more than one mutation in a cell in order for it to become cancerous. Most of the time either the mutation is relatively harmless, the DNA is repaired or the cell ‘kills itself’ before it can do any harm (apoptosis). However, in cancer cells the signals telling them to undergo apoptosis can be overridden so that the damaged cell continues to divide, producing even more damaged cells.

There are multiple methods currently in use to treat cancer, but the three most common treatments are surgery, chemotherapy and radiotherapy. In surgery, the tumour is simply removed from the body however this only completely cures if the cancer is contained in one area and hasn’t spread. Surgery is often used in combination with other treatments such as chemotherapy to shrink the tumour before surgery (neo adjuvant treatment).

Chemotherapy is the use of drugs to treat cancer, usually by stopping cells from dividing. The drugs do this by either preventing DNA from replicating (which occurs in the time preceding mitosis) or by interrupting mitosis during the metaphase stage. Chemotherapy is most effective against rapidly dividing cells like cancer cells but it can also effect other cells which divide frequently such as hair-producing cells. This explains some of the side effects such as loss of hair that can occur during chemotherapy.

Radiation works by damaging the DNA in cells that are dividing using high-energy rays (normally x-rays). Seems confusing, doesn’t it, given that cancer itself occurs due to damage to DNA in the first place? Radiation is different because the way in which it damages the cells means that they can’t grow or divide anymore. That damage can generally be repaired in normal cells, but not always which is why there are unwanted side effects to radiotherapy, but cancer cells cannot fix themselves so they die over time.

So now that you are clued up on how cancer occurs and can be stopped, back to carbon-dating. Carbon dating is used to determine the age of organic matter by measuring the amount of carbon-14 that they contain, but here’s the burn- I’m not really talking about carbon dating. Sorry! Don’t leave just yet, because what these scientists did to find out when various stages of cancer progressed in a patient is still pretty interesting. The researchers used genetic analysis and mathematical models that’s normally used in evolutionary biology and applied it to cancer instead. In evolutionary biology, genetic data from current species can be used in combination with carbon-dated fossils of ancestral species to estimate when the current species- or species in between ‘now’ and ‘then’- arose throughout history. Now you can perhaps see why the carbon-dating link comes in.

These methods could only be applied, however, due to a needle tract tumour which occurred when a biopsy of the patient’s tumour was taken. What this means is that a sample of the cancer was taken using a needle and where that needle was removed, some of the cancer cells contaminated the needle track. These cancer cells grew into a metastatic tumour (tumour which has spread from the primary site of cancer to a different area) but because the scientists knew exactly when this tumour happened, the genetic data from these cancer cells could be analysed and compared etcetera etcetera so that a timeline of how the cancer had started and spread was made.

This timeline is useful because it could help with diagnosis and treatment, not only directly but also from what else the scientists found. The researchers discovered that the cancer spread faster during the first year, however after metastasis this progression slowed. What this suggests is that the degree of genetic instability may play a more important part in the deadliness of cancer  than the amount that the cancer has spread. This could be used to determine a patient’s prognosis more accurately, and could help doctors when evaluating how well a treatment might- or might not- work. Furthermore, tracking a cancer’s progression could enable doctors to better predict the cancer’s behaviour in the future thus influencing the strategy for treating it.

So that’s a bit of information about what cancer is, how it can be treated and a recent research development in the field. Some of what I have shared in this post, I learnt at a ‘medicine insight day’ hosted by a group of medical students at Oxford University. They shared with us tips on how to get into university, explained some of the science in cancer and educated us about ovarian and testicular cryopreservation- a method to preserve the fertility of teenagers who have survived cancer.

This preservation is necessary because if a young person survives cancer, the treatment against cancer is often so aggressive that an ‘early menopause’ is triggered in the patient meaning they become infertile (unable to have children). The Future Fertility Trust is  charitable trust fund which offers cryopreservation in which ovarian or testicular tissue is collected, stored and re-implanted after cancer treatment. This enables young cancer survivors to have children in later life, however the work is not funded by the NHS so relies on donations and fundraising. I would like to see ovarian and testicular cryopreservation help more young people and hope that it might become available to all young people by the NHS is the future, and this could be possible if enough cases are funded to show the usefulness and success of  the technique. If you would like to find out more about cryopreservation, Future Fertility Trust, or to donate, go to http://www.futurefertilitytrustuk.org.

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