The last several months I've been immersed in a six-part project on cancer therapy, a topic that is at once bleak and exciting. Targeted agents in development and genetic profiling for individualized treatment suggest a future of increasingly hopeful outcomes. Nevertheless, the million dollar question for people who receive a diagnosis of aggressive malignancy remains, How long have I got?
Clinical trials in these settings typically use median survival--overall survival or progression-free survival--as the measuring post by which to compare one treatment regimen to another or to placebo or observation. To review statistics 101, the "median" number in a series of numbers is the middle value, with half the numbers above and half the numbers below. For example, if 32 apples are distributed among 7 children, with one child receiving one apple, three children receiving four, two receiving five, and one receiving ten, the median number of apples is four. An understanding of median is important in thinking about survival data because the upper and lower range of numbers in the series doesn't change the median. If instead of 10 apples, the last child in the example above received 1,000 apples, the median would still be four. (In contrast, mean is the average of all the numbers in the series and mode is the most common). In cancer terms, if the median survival is one year, the survival for some is a few months, and for others, many years.
For Christmas 2007, my son gave me a book of essays by Harvard professor and evolutionary biologist Stephen Jay Gould called The Richness of Life (great title!). One of the essays, "The Median Is Not the Message," is about the hope inherent in statistics, contrary to popular belief. In 1982, Gould was diagnosed with abdominal mesothelioma, a particularly aggressive form of cancer with a median survival of eight months. He read everything he could about cancer, this cancer, and survival statistics. Once he realized, with relief, the extended possibility of survival beyond the median, he knew he had time to "think, plan, and fight." He flung his efforts into increasing his odds of landing at the far end of the survival range, which he succeeded in doing, living for 20 more years.
His essay explains in very understandable terms the good news he found through his analysis of statistics. It's worth a read if you have cancer, know someone with cancer, are afraid of cancer, or just want to have some practice looking at a negative situation from a positive point of view. You can find the essay in the anthology I mentioned or on numerous cancer advocacy sites, including here.
It is the day before New Year's Eve and so a more appropriate post on this day might be a hip-hooray for the fresh start ahead, or a musing on how the changing economy colors the outlook for the coming year, or even a preview of what I'll be serving guests as the clock strikes midnight. But I'll stay with this post anyway. After all, what better time to focus on the who-knows-what-is-possible streaming flare of life than hours before a new year begins.
Figure source: http://www.stat.psu.edu/online/development/stat500/lesson02/lesson02_02.html