Marginal revolution

Orac has a great post on the cost-effectiveness of cancer treatments, particularly Avastin, an extremely expensive angiogenesis inhibitor.

Basically, what is being discussed here is whether a drug affects overall survival (OS), which is mortality from all causes in a cancer patient, versus whether it affects progression-free survival (PFS), which is the period of time before a given tumor progresses. Surprisingly, at least to non-oncologists and lay people, OS and PFS are often unrelated. If, for example, a drug slows tumor growth sufficiently to demonstrate a significant affect on PFS, it doesn't necessarily mean that OS will be better too. Sometimes it will, sometimes it won't. Moreover, it's long been a debate over whether PFS is a valid endpoint for approving a drug. Traditionally, the thinking has been that if a drug does not improve OS, then it probably shouldn't be approved as a first line agent given up front to new cancer patients who have not been treated yet, although it can be approved as a second-line or third-line agent, to be tried after first line agents fail.

However, thinking has been evolving over the last few years towards accepting a somewhat looser standard of valuing PFS. . .

. . . resources are not endless, and one has to ask how much a few months of PFS without a concomitant increase in OS are worth. I don't know the answer to that one, as this is a very difficult debate that we in the U.S. have thus far been able to avoid. Our colleagues in nations with nationalized health care systems cannot avoid it, though. For example, in Canada, it's been estimated that the addition of Avastin to breast cancer and lung cancer treatment would add $299 million a year to Canada's health care costs. In a country like Canada, the only choices are to cut money out of other programs to pay for this or to raise taxes. In the U.S., our insurance premiums just go up.

Everyone in the healthcare debate is looking for a villain: heedless consumers, careless doctors, grasping pharma companies. But the truth is, most of the increase in health care costs comes from new treatments, not abuse of the system. And a lot of those new treatments raise a question: how much are we willing to pay for marginal improvements in survival, or quality of life?

As Orac says, so far we've ducked that question because we have no central planner that has to make it. But eventually, we're going to have to face it through the mechanism of rising premia. And there's no easy answer. It's easy to dismiss these improvements as marginal, but marginal is not the same thing as "insignificant". Baby steps will eventually bring you to the same place as one giant leap--it just takes a little longer. My understanding is that the reason we've made such immense advances in pediatric oncology is that the oncologists just kept grinding away, producing minor improvements that over time added up to a gigantic increase in life expectancy for children with cancer.