5-Year Survival Data Not Always a Good Measure of Progress

Extract

The 5-year survival rate used to measure progress in the current SEER analysis of adolescent and young adult cancer prognosis is controversial. Although the statistic is common in cancer research, many experts suggest that it can also be prone to biases and misleading results.

Of chief concern is that 5-year survival rates are heavily influenced by the time of diagnosis, says H. Gilbert Welch, M.D., who codirects the Veterans Administration Outcomes Group at Dartmouth Medical School in New Hampshire. To illustrate how that skews their interpretation, he offers the following example: Consider two individuals who both contract cancer at age 42 and then die from it at the age of 50. However, one isn't diagnosed until age 47, while the other is diagnosed at age 42. The first patient lives 3 years with a cancer diagnosis and contributes nothing to 5-year survival, while the second patient lives with the diagnosis for 8 years. Nevertheless, both patients live with cancer for the same duration and die from it at the same age.