Evaluation of the learning curve for conformal sphincter preservation operation in the treatment of ultralow rectal cancer.

BACKGROUND: To investigate the learning curve of conformal sphincter preservation operation (CSPO) in the treatment of ultralow rectal cancer and to further explore the influencing factors of operation time. METHODS: From August 2011 to April 2020, 108 consecutive patients with ultralow rectal cancer underwent CSPO by the same surgeon in the Department of Colorectal Surgery of Changhai Hospital. The moving average and cumulative sum control chart (CUSUM) curve were used to analyze the learning curve. The preoperative clinical baseline data, postoperative pathological data, postoperative complications, and survival data were compared before and after the completion of learning curve. The influencing factors of CSPO operation time were analyzed by univariate and multivariate analysis. RESULTS: According to the results of moving average and CUSUM method, CSPO learning curve was divided into learning period (1-45 cases) and learning completion period (46-108 cases). There was no significant difference in preoperative clinical baseline data, postoperative pathological data, postoperative complications, and survival data between the two stages. Compared with the learning period, the operation time (P < 0.05), blood loss (P < 0.05), postoperative flatus and defecation time (P < 0.05), liquid diet time (P < 0.05), and postoperative hospital stay (P < 0.05) in the learning completion period were significantly reduced, and the difference was statistically significant. Univariate and multivariate analysis showed that distance of tumor from anal verge (≥ 4cm vs. < 4cm, P = 0.039) and T stage (T3 vs. T1-2, P = 0.022) was independent risk factors for prolonging the operation time of CSPO. CONCLUSIONS: For surgeons with laparoscopic surgery experience, about 45 cases of CSPO are needed to cross the learning curve. At the initial stage of CSPO, beginners are recommended to select patients with ultralow rectal cancer whose distance of tumor from anal verge is less than 4 cm and tumor stage is less than T3 for practice, which can enable beginners to reduce the operation time, accumulate experience, build self-confidence, and shorten the learning curve on the premise of safety.

[Molecular classification of colorectal carcinoma based on integration of gene expression profile and copy number variation].

OBJECTIVE: To classify colorectal carcinoma (CRC) by TNM staging integrated with the gene expression profile and copy number variation (CNV). METHODS: Profile data of gene expression and CNV of CRC were downloaded from public database and processed with batch bias adjustment, quartile normalization, missing value estimation and feature filtration. The processed profiles of mRNA and CNV were introduced into the codes of Bayesian consensus clustering (BCC) method and were used to calculate the subclasses of CRC. With the follow-up information of disease free survival of CRC patients, the prognostic values of the subclasses was investigated and the software of function enrichment analysis was employed to discover the major pathway signaling to each interesting subclass. All statistic analyses were performed under R-3.0.1 environment or by using SPSS 16.0 software. RESULTS: Profile data of gene expression and corresponding CNV from 335 CRC patients with TNM stage Ⅱ-Ⅲ and followed-up information were obtained. After feature filtering, the profiles contained 1578 probes of mRNA and 345 location of CNV. Four CRC subclasses were identified by the integrative analysis with BCC, and the concordances of BCC subclasses and each of gene-based subclasses (Cramer's V=0.49), CNV-based subclasses (Cramer's V=0.51) and Marisa's subclasses (Cramer's V=0.32) were statistically significant (Ps<0.001). Among BCC subclasses, BCC-I had a favorable prognosis, while BCC-Ⅳ had more unfavorable prognosis. The differences of prognosis were significant among BCC-I, BCC-(Ⅱ+Ⅲ) and BCC-Ⅳ with an overall log-rank P<0.001. The top enriched function was DNA damage and repair signaling when BCC-I compared to BCC-Ⅳ, and the new subgroups classified by the genes associated with enriched signaling had the better prognostic value than BCC subclasses but both of them were significantly correlated (Cramer's V=0.39, P<0.001). CONCLUSION: BCC method is effective to integrate multi-type genomic data for molecular classification of colorectal carcinoma, and the BCC-Ⅳ subclass has poor prognosis, which may be associated with the decreased repairing function of DNA damage.