Figure 3. Empirical Risk of Recurrence or Death over Time According to ER Status.

Risk was calculated as the number of events during the year divided by the number of patients at risk for experiencing the event at the beginning of the year. Cumulative at-risk sample sizes over time are shown in the respective panels of Figure 2. In the rightmost parts of the curves the samples were relatively small, and the standard errors (not shown) were correspondingly large. Not all patients have reached the later follow-up times. In addition, patients with earlier recurrences have been eliminated from the at-risk group.