We are living in an age of transition. Things are changing in the world of oncology, and these changes are going to have major ramifications for the clinical experiences of future cancer patients. In the last 30 years, there has been a huge improvement in cancer survival, as shown in the figure. Now, there are multiple reasons for these improvements.
The development of, and the advances in, diagnostic testing methods has led to earlier disease detection – and earlier diagnosis improves the likelihood of survival. Also, improvements in scanning machinery coupled to the huge advances in computer technology has led to the development of precise, real time 3D imaging of tumours which has improved the targeting of radiotherapy beams and surgical excision – which has, itself also been proved by advances in keyhole surgery techniques. Finally, the ongoing development of new chemotherapy drugs has increased the front-line and post-operative treatment options available to clinicians.
Now, all of this has made a difference. A massive difference. But more needs to be done. And one big change that is coming – one that is being mentioned more and more – is the future potential of Personalised Medicine.
And this, Personalised Medicine, is the transition I started this post with. Clinicians are starting to change the way they think about cancer – about what it is. Or, to be more accurate, what they are – not a single disease, remember! And this is leading to changes in how clinicians appraise the different treatment options available.
Now, I’ve mentioned before, cancer is an umbrella term for multiple diseases (see No Cure For Cancer…?). So, breast cancer is different from colorectal cancer, which is different from lung cancer….etc, etc. And I also mentioned in No Cure For Cancer…? that lung cancer is not one, single disease either, but can be subdivided into a variety of different cancers, which may require a variety of different treatments.
This type of thinking isn’t new, it’s how clinicians have thought about cancer for many years, and has, therefore, influenced both disease diagnosis and treatment scheduling. But this is now changing. It’s becoming more and more obvious that even this myriad of subdivisions is actually overly simplistic and the reality of each patient’s individual disease is much more complicated.
The reason for this is actually very simple. Each of us is a unique individual. We have our own unique genetic makeup. Also, our own individual life experiences mean that the environmental factors we are exposed to, while not completely specific to each individual, are not going to be exactly identical to anybody else’s either.
And, as I’ve mentioned previously, cancer derived from a patient’s own cells. Therefore, logically, if each patient is unique and their disease arises from themselves then this must mean that each patient’s disease is unique too! The specific environmental factors each person is exposed to, coupled to the distinct genetic makeup of every individual, means that the risk of developing cancer (in any form) is likely to be different from person to person. But, also, the way a cancer grows and spreads will likely be different from person to person too, as will the way the tumour responds to treatment, even if the tumours themselves appear to be similar at first.
So, consider the situation where two patients get diagnosed with the same disease, at the same stage, on the same day. They may appear to be identical and, up till now, this has been the criteria used by clinicians to plan treatment options. Oh, there will certainly be a whole lot of tests done to look at tumour markers, but on the whole the treatment options that are chosen will be based on size, position & stage of disease.
But actually, there is no guarantee that these two patients will respond to the same treatment in the same way. This is because their tumours, despite the outward similarity, will actually be very different at an intracellular level. They will have different genetic backgrounds, different metabolic rates and will be exposed to different environmental factors. All because of the differences between the patients themselves.
And it is this – the fundamental differences between the tumours – that influence the success of different forms of treatment. Different chemotherapy drugs target different proteins inside cells (the “Bills” from my Drug Discovery posts). So, in the example above, the two patients with outwardly similar tumour will be treated with the same chemotherapy drug. But, if one patient lacks the protein that drug targets, or has a mutation in the gene that makes it (which in turn changes the way it is put together), then the drug won’t work in this patient. And the tumour will progress in that patient.
But this is starting to change. Scientists are starting to investigate the tumours from individual patients, in order to identify the specific genes and other tumour-specific markers that can influence drug activity, tumour growth, disease progression etc, etc. Recently, a major study in Breast cancer identified 93 different genes which could influence Breast cancer growth and development. Now, these 93 genes don’t all do the same things, they are all different. And not all 93 have to be present to get the disease.
But the presence or absence of these specific genes can influence how a tumour grows. So, patient 1 might have, say, 5 of them. If so, which 5? What do those individual genes control? Patient 2, however, has 10 of them – a different subset, with no overlap to patient 1’s markers. What do these 10 genes control? How will they influence tumour growth, treatment efficacy, etc?
And this is just the beginning. Similar genotyping studies are being carried out for other types of cancer. And it will be the results of these studies that will change treatment planning. In future, when a patient is first diagnosed, as well as assessing the position, placement and stage of the disease, clinicians will also assess the specific genetic makeup of that individual patent’s individual tumour. And then they will tailor the treatments they offer, in order to meet that patient’s specific requirements.
So remember: You are an individual. Your disease is also individual. And, in future, your treatment will be individual too.
Welcome to the age of Personalised Medicine.
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