A commentary on ‘Minimally invasive surgery versus laparotomy of non-metastatic pT4a colorectal cancer: a propensity score analysis’
Authors: Xiao-Lin Zhao, Xue-Lei Li, Zhi-Peng Liu, Xian-Yu Yin, Zhi-Yu Chen, Hui Zhang
Journal: International Journal of Surgery (2023)

To the Editor, With great interest, we read the article by Dr Guo et al.1. This article is a multicenter study involving an analysis of comparison of short-term and long-term oncological outcomes between the minimally invasive surgery (MIS) group and laparotomy (Lap) group for non-metastatic pT4a colorectal cancer. The authors retrospectively analyzed the outcomes of 634 patients treated with radical operations in three tertiary hospitals with 1:1 propensity score matching (317 patients in the MIS group and 317 patients in the Lap group). They found that the long-term outcomes of MIS were not inferior to those of Lap in 5 years, but the short-term outcomes of MIS were better. This is a great finding; however, after carefully reading the article, we would like to raise the following questions regarding some details. First, we noted that the t-test was in the presentation of statistical methods, whereas chi-square (χ2) and nonparametric tests were used in this study. In addition, logistic regression analysis was mentioned in statistical methods, while Cox regression analysis was used in practice. The statistical methods mentioned by the authors do not accord with practical application. In addition, the discussion section compared the time of MIS with that of Lap and considered that MIS is shorter than Lap, which is not consistent with the article. Second, we noted that in Figure 4, patients with higher CA125 and larger tumor length had lower total points and better overall survival in the nomogram prediction model, while the N2 stage of lymph node corresponded with the lowest points and the best overall survival. Similarly, in Figure 5, higher CA125 and larger tumor length corresponded with lower points. The above results are obviously not consistent with clinical practice2,3. Whether the authors can explain that? In addition, the value of a model is reflected in its clinical application. Could the authors supplement the AUC (area under the curve) values of their prediction models in the online version so that surgeons can understand the prediction performance of their models4? Third, the authors pointed out that propensity score matching cohorts were 317 and 317 individuals in MIS and Lap, respectively. However, in the corresponding Figure 3, the cohorts the authors wrote were 227 and 227 individuals, respectively. The comments on the pictures do not match the content of the article. Finally, I would like to thank Dr Guo et al. for their study on the comparison of short-term and long-term oncological outcomes between minimally invasive surgery and laparotomy for non-metastatic pT4a colorectal cancer, which will undoubtedly promote the development of minimally invasive surgery for colorectal cancer. We believe that minimally invasive surgery will play an important role in the treatment of patients with malignant tumors. Ethical approval Not available. Sources of funding Chongqing Technology Innovation and Application Development Special Key Project (No. CSTC2021jscx-gksb-N0009). Author contribution X.-L.Z.: formal analysis, conceptualization, and writing – original draft; X.-L.L.: methodology and writing – review and editing; Z.-P.L.: conceptualization and supervision; X.-Y.Y.: literature interpretation and writing – review and editing; Z.-Y.C.: funding acquisition; H.Z.: conceptualization, supervision, and writing – review and editing. Conflicts of interest disclosure All authors have declared no conflicts of interest. Research registration unique identifying number (UIN) Name of the registry: not available. Unique identifying number or registration ID: not available. Hyperlink to your specific registration (must be publicly accessible and will be checked): not available. Guarantor Hui Zhang.