... the drug companies sit on the patents forever and can charge what they like for them.
Much as I dislike disagreeing with people, my understanding is that this is not so.
I think the life of a patent in the US is 20 years (it's probably similar in other countries), and since the patent has to be filed fairly early in the drug discovery process, well before it can actually be sold, the period when it's actually producing a profit for the patent-holder is quite a bit shorter. Once it's out of patent, anyone can make it (subject to getting a suitable manufacturing licence) and the original patent-holder gets no money from them.
Bear in mind also that the cost of developing a new drug is of the order of a billion US dollars. That R&D cost has to be covered from income on existing drugs, or else there will very shortly be no more new drugs. Very often, the drug companies cannot charge what they like; in countries with state health systems, for example, drug prices will, be negotiated between the manufacturers and the state, and end up below the manufacturers' list prices.
My source for all of this? The
In The Pipeline blog. I've linked to it before, in connection with some exciting chemistry; it's written by a chemist working in drug discovery, and unsurprisingly he has quite a lot to say about
drug pricing.
I sometimes think one of the reasons cancer hasn't been cured yet is that it is a most profitable business in treating it.
Again, I disagree. "Big pharma" could make a fortune with an effective, reliable cure for cancer, and indeed is spending fortunes at the moment in the search for cures. The reason it hasn't been cured yet is simply that it is
very, very difficult. Biological systems are orders of magnitude more complicated than any sort of engineering. In fact, there isn't an "it" to cure - the thing we call cancer is a multitude of different diseases, each of them a different way in which the growth of human cells can go wrong, and very often requiring different treatment. The source for all this is, again,
In The Pipeline.