In the Original Investigation titled "Estimates of Overall Survival in Patients With Cancer Receiving Different Treatment Regimens: Emulating Hypothetical Target Trials in the Surveillance, Epidemiology, and End Results (SEER)--Medicare Linked Database,"^[@zcx200015r1]^ published March 5, 2020, the authors were in violation of the SEER-Medicare data use agreement and had to remove data from 1 sentence in the Results and remove or replace data in the Supplement. The second sentence of the fifth paragraph of the Results should read as follows: "Compared with 569 individuals in the existing randomized clinical trial,^15^ 940 individuals included in the present analysis were older (median \[range\] age, 74 \[66-93\] years vs 64 \[36-92\] years), more likely to be male (547 \[58%\] vs 298 \[52%\]), and less likely to have undergone prior chemotherapy (53 \[6%\] vs 45 \[8%\])." This article has been corrected.^[@zcx200015r1]^
