Personal decision on personalized medicine

The story begins with the situations of breast cancer I heard from a recent lecture. There are three possible cases if you find yourself with the disease. Roughly in 70% of the cases, you will need only an surgery to be completely cured. In 20% of the cases, you need not only the operation but also chemotherapy. And in the rest 10% of the cases, sadly no effective treatment is available yet. Traditionally you don't know which case you are in and you can only try your luck, but now you have the choice to be diagnosed which type you are in, and to determine what you need (which is a preliminary form of 'personalized medicine', don't ask me why it is). Now I am going to show that if the price of the diagnosis is higher than a threshold value, the 'personalized medicine' could be no help to a patient.

Here I just make an extremely simplified calculation, assuming the patients themselves pay and decide to pay everything or not, and assuming the fees are 10 dollars for surgery and 10 dollars for chemotherapy. (I know that's impossible~ Don't blame me!) Let's say if you are cured you feel like to earn 1000, just to make it calculable.

Before the diagnosis is available, you have two options. One is to spend 10 dollars for surgery only and try your luck. Then there is 70% possibility you spend 10 and get cured, 30% possibility you spend 10 and die. Your expected net benefit will be (-10+1000)*70% + (-10+0)*30%= 690.

The other option is if you want to maximize your odd to survive, you will spend 20 for both surgery and chemotherapy. Then your expected net benefit will be (-20+1000)*90% +(-20+0)*10%=880. If you are a rational person (and suppose you don't fear chemotherapy to that extent), this is definitely your choice.

Now we have great technology to diagnose you before any treatment. Let's suppose the diagnosis fee is also 10 dollars and you indeed choose to use it on yourself and pay the price. Then what's you net benefit?

First you definitely spend 10 for the diagnosis. You get -10.

Then in 70% of the cases, you spend another 10 and your are sure to be completely cured. You get (-10+1000)*70%=693.

In 20% of the cases you know you have to spend 20 and get cured, so you get (-20+1000)*20%=196.

Finally in 10% of the cases you are unlucky. You may choose to spend your rest of the life in peace and pay nothing on medical treatment. I know you may need something to make your life easier but here I just ignore them to simplify the calculation. You get 0.

If we add the above values up you expect to get a net benefit of -10+693+196+0= 879 when you are helped by the diagnosis. Surprisingly, it is even lower than your expected benefit when you don't have the diagnosis before.

Even if you think your life is priceless, let's say it's a very big value far greater than 1000 or 10^1000, the calculation still goes the same way and the diagnosis would not become your rational choice.

Upon calculation, only when the price of diagnosis is less than 9 dollars in this case people will practically think about using the new tech.

You may think if the basic scientific advances are strong enough and all the three cases would be cured via different but available treatments, then the dilemma will disappear. I haven't done the calculation yet,so let's hope.

And the nature of the disease matters too. Let's see if the 'no-hope' possibility increases from 10% to 40% and the former two possibilities are 30% each in the above case, the diagnosis becomes even more welcome and a price up to 11 dollars is still acceptable. When your chance of surviving becomes lower you are more likely to favor the diagnosis!

You can take into account the pain of chemotherapy, the happiness of being aware of your own exact case when doing the calculation, then the result will be different. Maybe a price higher than 10 is still acceptable when these factors are considered. However, the idea I am presenting here is, the cost matters when you try to push a new application onto stage, no matter how fancy and how 'useful' it looks like.

When all factors are considered, including the true prices of each treatment, the success rate for each case, the allocation of the cost between the patient, the insurance company and the government and the emotional demand of the patient, the things will become more complicated but the cost and price determination still matters.

Personalized medicine is roaring onto the stage these days, generally claiming that the diagnosis and treatment shall be made specifically to each (or at least each type of) individual patient so that the disease can be properly cured.

I am not talking the innate dilemma underlying the conception, i.e. previously our medical guidelines are too cursory to treat patients properly, which is the reason we need personalized medicine; but if we push it to the other end there will be no guidelines at all and we need to do Aristotle's work in every single case where no guidelines could help at all, which is definitely not what we want. Yet nothing can be said as to where the compromise is.

I am not forgetting the scientific principles supporting the new concept either, which claim post-genomic advances will give a lot of hint on how a disease has originated and how the disorders can be overcome. I have no doubt of such a prospect except for the time needed to achieve that.

Considering the cost of personalized medicine in a broader vision, here is an excellent discussion by Daniel Callahan.