No Cure for Cancer….?

There’s a question that I’m often asked.  It happens all the time.  Whenever anyone finds out I work in cancer research, they will invariably ask something along the lines of, “So, when are you going to find a cure for cancer then?”  I don’t have the heart to tell them it’s not going to happen.  There Is No Cure For Cancer.

Now, that’s not to say that cancer can never be curable. Obviously, it can.  Survival rates are improving all the time.  What I mean is that there will never be one, single cure.

There are a couple of reasons for this.  The first reason is quite simple, but it’s not generally understood.  Cancer is not one disease. What we call cancer is actually a large variety of different conditions (over 200), which cause similar symptoms.  So, lung cancer is different from colorectal cancer, which is different from pancreatic cancer, which is different from…..you get the general idea.

But it’s even more complicated than that.  What we call “lung cancer” is not one disease either.  It can be separated into Small cell lung cancer (caused by smoking) and Non-small cell lung cancer.  And Non-small cell cancer can be further separated into another three diseases, namely squamous cell carcinoma, adenocarcinoma and large cell carcinoma.  Oh, and there’s also Mesothelioma, which is asbestos-related.  The same is true for diseases that affect other organs.  So, instead of one disease, that can appear in a variety of organs, there is a huge multitude of different diseases, affecting many organs throughout the body, all lumped together under the umbrella term “cancer”.

So.  That is Reason No.1.  There can’t be a single cure, because there isn’t a single disease.

Now for Reason No.2.

When most people talk about a “cure” for a disease, they are normally (knowingly or unknowingly) talking about a vaccine.  Over the last couple of centuries, medical science has become incredibly good at finding cures for diseases that previously proved fatal.  Smallpox, cholera, hepatitis A & B, influenza….the list goes on.  Now the way these vaccines work, is that they trigger the immune response and it is this immune reaction that kills the infection.  Basically, the patient cures themselves – all the vaccine does is give their immune system a kick-start.

Now, in the case of cancer, what you have to remember is that cancer arises from the patient’s own body.  It is part of them.  And this is the problem.  Every single cell in your body is covered in a marker that is unique to you., called the MHC (Major Histocompatability Complex).  The MHC acts like an “identity card” that allows your immune system to recognise the cells of your own body.  If your immune system comes across cells that do NOT have the correct MHC then it recognises them as “foreign invaders” and kills them.  Yup, your immune system hates “foreigners”.  It is the UKIP of biology.

This is what can happen if someone gets an organ transplant. Beforehand, the doctors have to seek out a matched donor – someone whose MHC is similar enough to the patient’s, so that the patient’s immune system won’t automatically attack the new organ.  This can be a close family member, but it can also be a total stranger.  Even when a donor is found whose MHC is compatible, the patient still has to take immunosuppressants (drugs which suppress the immune response) for the rest of their lives, in order to prevent organ rejection (which is what we call it when the immune system attacks the new organ).

But, in the case of cancer, this system works against the patient.  As the cancer has arisen from the patient’s own cells, the tumour cells have the correct MHC, therefore the immune system won’t recognise it as foreign and therefore leaves it alone.  So, the medical tricks we have learned to provide cures for other diseases simply don’t work on cancer.  (And in case you’re wondering, the same is true of other curative drugs, like antibiotics.  Antibiotics work against bacterial and fungal infections.  But cancer is neither, so these treatments will not, and cannot, have any effect.)

…And there we have it.  The reasons why there is no cure for cancer, and never will be.  But don’t get depressed!  As I said at the start, I’m not saying that cancer is incurable.  New treatments are being developed all the time, and survival rates are constantly improving.  I just ask you to remember how complicated the situation is.  Cancer, or to be more accurate, cancers, are difficult diseases to attack, but we are getting better at it all the time, and one day we’ll get there.  There may never be A Cure For Cancer, but, one day, cancer will be 100% curable.

ResearchBlogging.org

AG McCluskey (2015). No Cure for Cancer….? Zongo’s Cancer DIaries

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5 thoughts on “No Cure for Cancer….?

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