Objective To investigate the influence of perioperative probiotics supplement on short⁃term clinical outcomes in gastric cancer patients receiving neoadjuvant chemotherapy combined with radical gastrectomy.

Methods The prospective randomized controlled study was conducted. The clinicopathological data of 80 patients who underwent neoadjuvant chemotherapy combined with radical gastrectomy in the Affiliated Hospital of Qingdao University from July 2020 to September 2021 were selected. Based on random number table, patients were allocated into two groups. Patients undergoing perioperative probiotics supplement were allocated into the experiment group, and patients undergoing perioperative conventional treatment were allocated into the control group, respectively. Observation indicators: (1) grouping situations of the enrolled patients; (2) intraoperative situations; (3) follow‑up and postoperative situations; (4) inflammation related hematological indexes. Follow‑up was conducted using telephone interview and outpatient examina-tion to detect postoperative complications and startup of adjuvant chemotherapy up to October 31,2021. Measurement data with normal distribution were represented as Mean±SD, and comparison between groups was conducted using the independent sample t test. Measurement data with skewed distribution were represented as M(range), and comparison between groups was conducted using the Mann‑Whitney U test. Count data were described as absolute numbers, and comparison between groups was performed using the chi‑square test or Fisher exact probability. Comparison of ordinal data was analyzed using the Mann‑Whitney U test. Repeated measurement data were analyzed by the repeated ANOVA or generalized estimating equation.

Results (1) Grouping situations of the enrolled patients. A total of 80 patients were selected for eligibility. There were 51 males and 29 females, aged 64(42-80)years. Of the 80 patients, there were 40 patients in the experiment group and 40 patients in the control group, respectively. (2) Intraoperative situations. All patients in the experiment group and the control group underwent radical gastrectomy successfully. Cases with yield pathologic TNM (ypTNM) stage 0, stage Ⅰ, stage Ⅱ, stage Ⅲ after neoadjuvant chemotherapy, cases undergoing laparoscopic radical gastrectomy or Da Vinci robotic radical gastrectomy, the operation time, the volume of intraoperative blood loss, cases undergoing digestive tract recons-truction as Billroth Ⅱ anastomosis or Roux‑en‑Y anastomosis were 2, 7, 15, 13, 19, 21,205(180-240)minutes, 50(30-60)mL, 6, 34 in the experiment group, versus 4, 6, 12, 16, 23, 17, 218(190-251)minutes, 50(43-60)mL, 11, 29 in the control group, showing no significant difference in the above indicators between the two groups (U=683.00, χ²=0.80, U=668.00, 681.00, χ²=1.87, P>0.05). (3) Follow‑up and postoperative situations. All the 80 patients were followed up for 1 month after surgery. Cases with postoperative infectious complications were 6 in the experiment group, versus 15 in the control group, showing a significant difference between the two groups (χ²=5.23, P<0.05). The application of antimicrobial agent, time to postoperative first flatus, time to postoperative first defecation, time to tolerance of solid food, duration of postoperative hospital stay, time to postopera-tive startup of adjuvant chemotherapy were 3(3-6)doses, 53(49-66)hours, 72(62-82)hours, (72±18)hours, 6.0(5.5-7.0)days, 26.0(25.0-28.0)days in the experiment group, versus 6(3-10)doses, 66(60-88)hours, 94(82-112)hours, (107±23)hours, 7.0(6.4-8.3)days, 30.0(28.0-33.0)days in the control group, showing significant differences in the above indicators between the two groups (U=471.50, 432.00, 343.50, t=-7.62, U=411.50, 319.50, P<0.05). (4) Inflam-mation related hematological indexes. ① The white blood cell counts before surgery and at postoperative day 1, 3, 5 were (5.6±1.4)×10⁹/L, (9.9±3.2)×10⁹/L, (7.7±2.6)×10⁹/L, (6.8±1.8)×10⁹/L in the experiment group, versus (6.1±1.9)×10⁹/L, (12.3±2.9)×10⁹/L, (9.7±3.6)×10⁹/L, (7.8±2.7)×10⁹/L in the control group, meeting the mauchly′s test of sphericity (χ²=4.17, P>0.05). Results of intrasubject effect test showed that there were significant differences in the time effect, intervention effect and interaction effect of white blood cell counts between the two groups (F=106.61, 10.45, 4.56, P<0.05). ② The neutrophilic granulocyte percentages before surgery and at postoperative day 1, 3, 5 were 55%±10%, 76%±11%, 73%±9%, 69%±9% in the experiment group, versus 56%±9%, 84%±5%, 79%±8%, 74%±9% in the control group, not meeting the mauchly′s test of sphericity (χ²=16.63, P<0.05). Results of multi-variate test showed that there were significant differences in the time effect, intervention effect and interaction effect of neutrophilic granulocyte percentages between the two groups (F=92.42, 11.46, 5.55, P<0.05). ③ The levels of C‑reactive protein before surgery and at postoperative day 1, 3, 5 were 1.35(1.15-1.97)mg/L, 14.94(8.24-21.22)mg/L, 33.39(13.02-66.02)mg/L, 18.36(8.27-60.43)mg/L in the experiment group, versus 1.62(0.97-2.27)mg/L, 24.03(10.42-36.52)mg/L, 81.66(31.20-116.76)mg/L, 46.84(28.30-80.26)mg/L in the control group, not meeting the normal distribution. Results of generalized estimation equation test showed that there were significant differences in the time effect, intervention effect and interaction effect of levels of C‑reactive protein between the two groups (Waldχ²=145.74, 9.48, 9.90, P<0.05). ④ The levels of procalcitonin before surgery and at postoperative day 1, 3, 5 were 0.02(0.02-0.04)μg/L, 0.08(0.06-0.12)μg/L, 0.12(0.07-0.21)μg/L, 0.09(0.06-0.15)μg/L in the experiment group, versus 0.02(0.02-0.04)μg/L, 0.14(0.07-0.71)μg/L, 0.35(0.14-0.71)μg/L, 0.24(0.10-0.48)μg/L in the control group, not meeting the normal distribution. Results of generalized estimation equation test showed that there were signifi-cant differences in the time effect, intervention effect and interaction effect of levels of procalcitonin between the two groups (Waldχ²=62.88, 14.71, 18.33, P<0.05).

Conclusion Perioperative supple-ment of probiotics can reduce the incidence of postoperative infectious com-plications and the application of antimicrobial agent, promote recovery of gastrointestinal function, reduce the level of inflammation related indexes, shorten the duration of postoperative hospital stay and the time to postoperative startup of chemotherapy in patients undergoing neoadjuvant chemotherapy combined with radical gastrectomy.