This was a retrospective case-control study designed and conducted under the approval of the ethic committee of Tehran University of Medical Sciences. All patients with gastric cancer referring to Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran, during February 25th and December 25th 2020, were enrolled to the study.

This was a retrospective case-control study designed and conducted under the approval of the ethic committee of Tehran University of Medical Sciences. All patients with gastric cancer referring to Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran, during February 25th and December 25th 2020, were enrolled to the study. February 25th was the day Ministry of Health and Medical Education announced COVID-19 as a national disaster and set restrictive rules of social distancing. The control group consisted of the gastric cancer patients whom referred to Cancer Institute during February 25th and December 25th of 2019. So the investigators compared two groups of gastric cancer patients one in the era of COVID-19 pandemic and other group from previous year when there was no COVID-19.

Cancer Institute as the pioneer of cancer management in Iran set institutional regulation for hospitalization of cancer patients during COVID-19 pandemic with the primary goal of delivering the best available treatment as timely as possible. In order to achieve this, each patient regardless of cancer type must had proceeded these steps before elective hospitalization and during preoperative, operation and postoperative days:

1. Prior to hospitalization, patients were referred to infectious disease clinic, where they were visited by attending infectious disease specialists who had fellowship in infectious disease of immunocompromised and transplanted patients. Every patient monitored for COVID-19 sign and symptoms and those with high susceptibility were examined utilizing spiral chest computed tomography scan (SCCT) and polymerase chain reaction (PCR) for SARS-CoV-2. If a patient had positive result of either SCCT or PCR, he/she was managed either in outpatient or inpatient setting for COVID-19 treatment based on national protocol and subsequent cancer management was postponed. If it was confirmed that patient is eligible for hospitalization and entering operation room, he/she was admitted to surgical oncology ward.
2. During pre-operative days, all patients were hospitalized in single or double bed room, family members were not allowed to accompany except for under legal aged patient and those who need special attention because of the low performance status. All patients were educated about COVID-19 transmission routs and preventive measures and asked to respect social distancing, wear facial mask and wash hands using alcohol- based antiseptic formulas given. Each patient underwent daily monitoring for sign and symptoms of COVID-19, heart rate, blood pressure, temperature and oxygen saturation by commercially available pulse oximetry devices. In case of developing signs and symptoms related to COVID-19 or unexplained temperature > 38°C, oxygen saturation < 93% or > 5 unit drop in oxygen saturation from the baseline, infectious disease consultation was ordered.
3. During operation time, the minimum number of personnel needed to activate a safe operation environment whom were fully equipped with personal preventive clothing including surgical cap, gown, facial mask and shield were present at the theater. The operation theater was well ventilated.
4. During post-operative days, for both intensive care unit and ward patient, daily monitoring of signs and symptoms related to COVID-19 besides unexplained temperature > 38°C, oxygen saturation < 93% or > 5 unit drop in oxygen saturation from the baseline, C-Reactive Protein Level > 40 persistent for 3 days activated infectious disease consultation.

Patients of both case and control group were enrolled to the study as if they gave written consent of participation, had confirmed gastric cancer using esophago-gastro-duodenoscopy and pathologically proven biopsy and spiral thoraco-abdomino-pelvic computed tomography scan prior to surgery. All patients became candidates to undergo staging laparoscopy (SL) in order to investigate local and peritoneal invasion of the tumor based on National Comprehensive Cancer Network guideline for gastric cancer 2020. Patients with following criteria were excluded from the study; radiological evidence of metastatic disease, current or previous history of chemotherapy.

All patients of both groups underwent SL by the same two attending onco-surgeon, using the same technique and the same laparoscopic device. Under general anesthesia and in supine position SL was performed. A 10 mm optic laparoscopic port was inserted via the midline incision below the umbilicus using Hasson technique. All four quadrants of the abdomen as well as pelvis were inspected during laparoscopy and biopsy was taken from any suspicious lesion through insertion of 5mm port. All specimens underwent cytological evaluation by two independent pathologists. The presence of any malignant cells, regardless of the number, confirmed the positive cytology. In the event of discordant reports between two pathologists, specimens were sent for the third review by a pathologist who was blinded to the previous results. Laparoscopic evaluation was considered positive as if adjacent organ involvement, omental involvement or peritoneal seeding were seen.

Data were collected on the following variables: age, gender, tumor location, gastric lesion pathology and clinical stage based on the 8th edition of the American Joint Committee on Cancer tumor-node metastasis staging system for gastric cancer[16].

Categorical variables are shown as number and relative frequency. Also, continuous variables are shown as mean ± SD. Collected data for categorical variables were compared using the chi-squared test. An independent student t-test was used to compare means between the two groups. All analyses were performed by the two-sided method using Statistical Package of Social Science software (SPSS version 22; SPSS, Inc., Chicago, IL), and the p-value of < 0.05 was set as statistically significant.

Inclusion Criteria:

All patients became candidates to undergo staging laparoscopy (SL) in order to investigate local and peritoneal invasion of the tumor based on National Comprehensive Cancer Network guideline for gastric cancer 2020.

Exclusion Criteria:

Patients with following criteria were excluded from the study; radiological evidence of metastatic disease, current or previous history of chemotherapy.

All patients with gastric cancer referring to Cancer Institute, Tehran University of Medical Sciences, Tehran, Iran, during February 25th and December 25th 2020, were enrolled to the study.

data will be available up on reasonable request from Amirisina Sharifi.M.D.(a.s_sharifi@yahoo.com).