In this study, the 30% fall in case load during the COVID-19 period and the proportion of local patients in PCG being lower than those in CG could be attributed to the travel restrictions and lockdown imposed on Beijing. During the COVID-19 period, the use of telemedicine and remote counselling has made great strides. This has helped in reducing the number of outpatients and unnecessary physical contacts. Tolone et al. used triage questionnaires for elective surgical patients in cases of positive symptoms and contact history associated with COVID-19. These questionnaires were administered through the telephone [11]. Gambardella et al. reported their experience regarding treatment for old cancer patients. They documented several procedures that could help in preventing disease transmission among patients. These procedures encompassed the use of a telephone triage before admission, and the application of telemedicine [12]. In CG, appointments and triage protocols were to be performed virtually through telemedicine such as mobile phones, applications or the websites, thereby, clinical visits were to be performed based on reserved numbers and recommended time.
The COVID-19 outbreak brought to the importance of infection control measures for pandemic diseases. Successful implementation of infection control measures require the strict management of inpatients during this period. Patients with cancers have been established to be immunocompromised, which makes them more susceptible to COVID-19 [4, 10]. Therefore, we suggest that all outpatients should be triaged before admission to reduce the possibility of exposure in hospital. In CG, to screen for suspected infections, patients were subjected to chest CT scans and new coronavirus nucleic acid tests before admission, which explains the longer waiting time before admission in CG. In addition, the provinces were relatively isolated during the pandemic, therefore, compared with PCG, the proportion of local patients in CG had increased.
After admission, patients were isolated in separate single-room wards without contact to surgeons or nurses. If the fever was lower than 37.3℃ or other symptoms associated with pneumonia were absent after 3 days of admission, surgical procedures would then be performed. The waiting time before surgery was, therefore, longer. During the pandemic, routine surgical techniques should be based on the principles of safety and efficiency, with the main purpose of reducing the incidences of postoperative complications while accelerating the patient's recovery and discharge [13-15]. It was necessary to avoid performing surgical procedures beyond the established guidelines, including oversized lymph node dissections with uncertain effects and complex digestive tract reconstruction methods. For better surgical outcomes, attention should be paid during surgery to reduce the risk of bleeding. This decreases the chances for blood transfusion.
During COVID-19 period, more laparoscopic surgeries were performed. COVID-19 is mainly transmitted through respiratory droplets, but the risk of COVID-19 transmission is greatly increased during aerosol generation procedure (AGP) in laparoscopic surgery [16]. Compared with open surgery, there are concerns that the leaked CO2 and smoke may lead to the generation of COVID-19 contaminated aerosols, which may be due to the application of ultrasonic surgical instruments, low gas motility of pneumoperitoneum, and gas expulsion through trocars or ports [17]. Therefore, The Intercollegiate General Surgery Guidance on COVID-19 and The Society of Gastrointestinal and Endoscopic Surgeons (SAGES) initially highlighted the risk of aerosolization during laparoscopic surgery, although their updated guidance acknowledged a lack of evidence [18, 19].
However, both open surgery and laparoscopy could generate surgical smoke. When necessary preventive measures are taken, smoke control can be achieved in the closed cavity of laparoscopic surgery, while it cannot be properly controlled in open surgery. The key factors for safe control of smoke hazards are smoke evacuation completely purified by filters and intelligent use of ultrasonic surgical instruments.
We have rigorously analyzed the researches associated with surgical smoke and found there was lacking of enough evidence that laparoscopic surgery is routinely prohibited simply due to the aerosol generation procedure during operation. Moreover, there was less evidence that had shown relationship between COVID-19 transmission and surgical smoke generated by ultrasonic surgical instruments [20-23]. By the way, during the COVID-19 pandemic, we also use the smoke extractor with vacuum motors which were applied to inhale smoke from the surgical site through a completely enclosed vacuum tube and filter. Medical staffs were therefore protected from potential contamination. Therefore, we have used laparoscopy more frequently during COVID-19, and information about laparoscopic surgeries, such as surgery time, blood loss and complications, indicated that the method was safe and feasible. However, although we have not found any evidence of particular risk in laparoscopic surgery, the risk might still exist. Further investigation in this field is of critical importance.
The hospitalization costs were significantly increased in CG. As for the reason, we would like to elaborate on prolonged hospital stay. Patients in CG were observed in the separate single-room wards for three days to prevent potential infection. Therefore, the preoperative hospital stay was longer. As for the post-operative hospital stay, during the COVID-19 period, patients had to have their stitches removed in outpatient clinics and local hospitals after discharge. This increased the risk of unnecessary viral infections. It was better to stay longer in our department until stitches were removed. The hospital stay period after surgery was, therefore, longer in CG.
We found no statistically differences in postoperative fever. If the patient developed fever of unknown cause after surgery, appropriate ward isolation measures should be taken and measurements of postoperative blood routine, C-reactive protein, procalcitonin, chest CT, and new coronavirus nucleic acid tests were necessary.
Limitations
This study had some limitations. Firstly, the presented results are for a short-term follow-up period which fails to illustrate the long-term outcomes such as progression-free survival and mortality. Secondly, oversized lymph node dissections with uncertain effects were not performed beyond authoritative guidelines, which may have also impact on oncologic outcome. More studies are needed to investigate the impact of these procedures on oncologic outcomes. Thirdly, the study was retrospectively performed in a single center and may therefore involve selection bias.