As a scientist, Gould knew better. The median, the measure of central tendency used in this example, describes that point in a distribution that separates the cases in half. Half the people lived fewer than eight months, and half lived for a longer time. Yet we tend to see it as the one essential truth to be extracted from that statistic. In fact, the opposite is true.
All evolutionary biologists know that variation itself is nature's only irreducible essence.
Variation is the hard reality. Just as important, the statistics had been based on conventional treatment. With a new experimental protocol and the best medical care, he might well outlive even the best predictions. Fourteen years later, Gould considers himself a survivor. If you research the studies on treatment of metastatic disease, you are likely to encounter the same problems.