Every wonder why the new cancer advances, such as bevacizumab (Avastin), gefitinib (Iressa), cetuximab (Erbitux), trastuzumab (Herceptin) and so on, don’t work in most patients? Why their benefit is often hardly measurable? And why they cost so much (up to and over $100,000/year)
The reason is that cancer is complicated: (From the American Association for Cancer Research Meetings and the NY Times):
Through a series of random mutations, genes that encourage cellular division are pushed into overdrive, while genes that normally send growth-restraining signals are taken offline.
With the accelerator floored and the brake lines cut, the cell and its progeny are free to rapidly multiply. More mutations accumulate, allowing the cancer cells to elude other safeguards and to invade neighboring tissue and metastasize.
And:
But recent discoveries have been complicating the picture with tangles of new detail. Cancer appears to be even more willful and calculating than previously imagined.
Most DNA, for example, was long considered junk — a netherworld of detritus that had no important role in cancer or anything else. Only about 2 percent of the human genome carries the code for making enzymes and other proteins, the cogs and scaffolding of the machinery that a cancer cell turns to its own devices.
Medicynical Note: Read the article. It’s fascinating and makes clear that there are many unanswered questions and that a “cure” for cancer is not likely to happen soon.
Regarding cost, drug companies simply take advantage of the sick and infirm and overcharge.
Medicynic 
Amen! I refused Herceptin because the absolute benefit was just a little over 6%. In other words only about 6 out of 100 women with Her2+ cancer would benefit from a drug that costs about 50, 000 dollars for a one year treatment, the recommended course. The relative benefit of Herceptin in the NEJM Oct. 2005 was 55%, yet another way we are deceived as most people would take that as an absolute benefit.