Our response to the letter to the editor for the article "Comparison of survival between unilateral and bilateral breast cancers using propensity score matching: a retrospective single-center analysis".

They expressed their concerns about making comments regarding the sample size in our study. The preferred propensity score analysis was the statistical method chosen because it is the analysis after balancing the small number of patients with the much larger number of patients in this situation in terms of both number and prognostic factors. In fact, the reference to future studies on this subject has been made for new retrospective series rather than prospective randomized studies. We wanted to draw the attention of researchers to propensity score analysis and to show that future retrospective series studies can ask questions with clearer answers using propensity score analysis.