Correction to: International Journal of Clinical Oncology (2021) 26:1661–1670 https://doi.org/10.1007/s10147-021-01946-4

In the original publication, under Study design heading in Methods section, the sentence starting with: “The study was approved by…” should read as:

The study was approved by the Institutional Review Board of Saitama Medical Center at Saitama Medical University (925), the Ethics Committee of Saitama Medical University (747), and the institutional review board at each participating institution.

The original publication has been corrected.