Cancer Clinical Trials: what does “significant” mean?

When we hear the words there was a significant treatment effect, you would naturally assume that significant means large, important, or noteworthy. This may be true—but not necessarily. More often than not, significant refers to statistically significant, which means that the difference between the two groups of patients was statistically meaningful and unlikely to be random.

          Statistical significance is an important concept. Without measuring the statistical significance of study results in cancer treatment, it is possible that any effects may not even be real but rather just chance. However, statistical significance is not enough. Another medical term—clinically significant—means “important to patient care.” This is what we are after. If a small effect is statistically significant, it may still not be large enough for us to care much about it. Watch out for the word significant, and assume it’s likely “statistics-speak” and not necessarily the large, important improvement you might think.