Esophageal carcinoma (EC) is one of the most common malignancies worldwide, ranking seventh and sixth in terms of incidence and mortality in the world cancer spectrum, respectively (1). The major histological subtypes of EC include squamous cell carcinoma and adenocarcinoma, with esophageal squamous cell carcinoma accounting for most cases (1–3). At present, the treatment of esophageal cancer mainly includes surgery, radiotherapy, chemotherapy, and immunotherapy, and surgery is the main treatment. Despite improvements in minimally invasive treatment strategies (4, 5), surgery remains the mainstream curative management. However, esophagectomy is a complex procedure that has a high rate of postoperative mortality and morbidity, including pulmonary complications (6–10). Because of complications, the length of hospital stay is significantly long. The duration of recovery in the perioperative period was consistent in patients with EC. In this period, patients always experience fatigue and pain (11).

The weight of sputum is considered a predictive indicator of pulmonary complications (12). Several studies have indicated that sputum contains microorganisms that could cause diseases, such as pneumonia and systemic inflammatory response syndrome (7, 13). The Borg scale was used to assess the tolerance of patients who engage in aerobic exercises (14, 15). The 6-min walk test (6-MWT) can be used to identify heart and lung function to some extent after surgery (16–18). Moreover, the Borg scale and 6-MWT can be utilized to evaluate the recovery of patients after surgery.

In the beginning, the active cycle of breathing technique (ACBT) provides a short-term improvement in secretion clearance in individuals with lung diseases, particularly non-cystic fibrosis bronchiectasis and cystic fibrosis bronchiectasis (19–24). In patients with cystic fibrosis, additional physical treatment, including ACBT, can improve muscle function, oxygen saturation, and small airway function and can reduce dyspnea. ACBT, which comprised breathing control and huff, was developed using the forced expiration technique and resulted in fast-track recovery after thoracic surgery. A typical ACBT is composed of breathing control, thoracic expansion exercises, and the forced expiration technique. The frequency of ACBT is flexible. However, all parts of the cycle must be included and interspersed with breathing control. A previous study has indicated that ACBT could increase the volume of sputum and the 6-MWT and Borg scale scores in patients with lung cancer who underwent lung resection (25).

The current study focused on the effect of ACBT on the perioperative outcomes in patients with EC who underwent esophagectomy. The following clinical observational indicators were used to assess the effect of ACBT: the weight of sputum, length of hospital stay, Borg scale score, anastomotic leakage, and 6-MWT score.

To the best of our knowledge, this study is the first to observe ACBT training in EC patients. The cases were divided into the observation and ACBT groups. We provided ACBT training before surgery, with the hope that this technique could improve the outcomes of rapid rehabilitation in patients after esophagectomy. In the course of the study, we used the 6-MWT and Borg scale to evaluate the tolerance of aerobic exercise in patients with EC before and after surgery. We collected data about weight of sputum, smoking index, tumor location, pTNM stage, pathway of surgery, surgical approach, anastomotic leakage, and length of postoperative hospital stay. These data were analyzed using statistical tools. The results of this study confirmed that ACBT could increase the weight of sputum and tolerance to aerobic exercises after surgery in EC patients, based on the results of Yang Mei's study about lung cancer (25). To reduce confounding effect of the smoking index, age, surgical approaches, and tumor location on the observed indicators, we used the chi-squared test, CMH test, and Kruskal–Wallis test to assess the data before surgery. We found that the mean weight of sputum in the observation group was lighter than that in the ACBT group. On the basis of the above-mentioned results, ACBT training could increase the weight of sputum after esophagectomy; thus, patients should receive ACBT training before surgery to help them cough sputum much easier. Using the Borg scale, we found that the mean score was not different between the observation and ACBT groups before surgery; however, the 6-MWT scores before surgery differed between the observation and ACBT groups. After surgery, the ACBT group had better outcomes than the observation group. Based on the analysis of pre-surgery data, we found that the mean distance achieved in the 6-MWT was longer in the ACBT group than in the observation group (P = 0.024). We combined the scores of the 6-MWT and Borg scale to assess tolerance of aerobic exercise, and results showed that ACBT could improve this tolerance after surgery.

We paid more attention to the findings associated with complications, which were a major concern of our research. Anastomotic leakage was considered to be the main cause of prolonged hospitalization. In this research, 16 patients had anastomotic leakage, among which 1 case occurred in the ACBT group and 15 cases occurred in the observation group. The occurrence rate of anastomotic leakage was significantly different between the two groups. We speculated that ACBT might decrease the occurrence of anastomotic leakage.

The length of postoperative hospital stay decreases with the reduction in complication rate. In our study, the ACBT group had a shorter length of postoperative hospital stay than the observation group. Thus, ACBT was likely to improve the outcomes of postoperative surgery in EC patients. Compared with previous studies, this study had a larger sample size and a higher number of patients who underwent esophagectomy.

The present study had some limitations. It was conducted at a single institution, and the sample size was relatively small. Therefore, multicenter studies with larger cohorts must be conducted to validate the results of the current study. Lacking related information of BMI, nutrition status and neo-adjuvant therapy was another drawback. In future studies, these factors should be taken into consideration to evaluate their impact on perioperative outcomes. Moreover, although patients with various histological types were included in this study, squamous cell carcinoma took the lead due to its prevalence in China and thus causing the disproportion of histology type. Given that it was the perioperative outcomes that we focused on, unbalance in the histology type barely had impact on the results. Nevertheless, these patients required longer observation and follow-up. Thus, prospective studies must be performed to validate the results of this study.

In a conclusion, ACBT is likely to help patients of EC improve perioperative outcome after esophagectomy, which may decrease the time of hospital stay. However, more prospective studies are needed to explore the impact of ACBT on postoperative complications in EC patients after esophagectomy.

The datasets presented in this study can be found in online repositories. The names of the repository/repositories and accession number(s) can be found below: https://www.researchdata.org.cn/Default.aspx. Approval number: RDDA2019001345.

The studies involving human participants were reviewed and approved by Ethics Committee of Sun Yat-sen University Cancer Center. The patients/participants provided their written informed consent to participate in this study.

C-ZL, G-WM, J-DZ, and HY designed the research. L-LW and S-WZ processed data and wrote the draft. S-WZ, MW, C-ZL, and W-JW recorded the data of patients. All authors observed the patients. HY, G-WM, W-JW, and J-DZ reviewed and edited the article. All authors contributed to the article and approved the submitted version.

This work was supported by Guangdong Esophageal Cancer Institute Science and Technology Program (No. Q201601).

The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.

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