Ethical statement
All procedures performed in studies involving human participants were in accordance with the ethical standards of the institutional and/or national research committee and with the 1964 Helsinki declaration and its later amendments or comparable ethical standards. The study protocol was approved by the Institutional Review Boards of the JOCSC (No. 26-01, Aug. 5, 2014). Informed consent was obtained from patients. Although the analysis was retrospective, data for the anonymized JOCSC database were collected in a normal clinical setting, and the confidentiality of the patients involved was protected. All patients’ records/information was anonymized and de-identified prior to analysis.