High incidence of gallstones after Roux-en-Y reconstruction gastrectomy in gastric cancer: a multicenter, long-term cohort study

Background: Roux-en-Y reconstruction is a common anastomosis technique during gastrectomy in gastric cancer. There is a lack of studies on gallstones after Roux-en-Y reconstruction gastrectomy. This study investigated the incidence and potential risk factors associated with gallstones after Roux-en-Y reconstructive gastrectomy in gastric cancer. Methods: The study analyzed data from gastric cancer who underwent radical gastrectomy and Roux-en-Y reconstruction at two hospitals between January 2014 and December 2020. The patients fall into distal and total gastrectomy groups based on the extent of gastrectomy. The cumulative event probability curve was plotted using the Kaplan–Meier, and differences in gallstone between groups were evaluated using the Log-Rank. Propensity score matching was applied to construct a balanced total versus distal gastrectomies cohort. A Cox regression was employed to analyze the risk factors for gallstones after Roux-en-Y reconstructive gastrectomy in gastric cancer. Further subgroup analysis was performed. Results: Five hundred thirty-one patients were included in this study, 201 in the distal gastrectomy group and 330 in the total gastrectomy. During the follow-up, gallstones occurred in 170 cases after gastrectomy, of which 145 cases accounted for 85.29% of all stones in the first two years after surgery. Then, to reduce the impact of bias, a 1:1 propensity score matching analysis was performed on the two groups of patients. A total of 344 patients were evaluated, with each subgroup comprising 172 patients. In the matched population, the Cox regression analysis revealed that females, BMI ≥23 kg/m2, total gastrectomy, No.12 lymph node dissection, and adjuvant chemotherapy were risk factors for gallstones after Roux-en-Y reconstructive gastrectomy. Subgroup analysis showed that open surgery further increased the risk of gallstones after total gastrectomy. Conclusion: The incidence of gallstones increased significantly within 2years after Roux-en-Y reconstructive gastrectomy for gastric cancer. Patients with these risk factors should be followed closely after gastrectomy to avoid symptomatic gallstones.


Introduction
Gastric cancer is the fifth most common cancer and the fourth leading cause of cancer-related deaths worldwide [1] .The primary treatment method for resectable gastric cancer is radical gastrectomy.This procedure can disrupt the normal physiological pathways, affecting gastrointestinal function and increasing the risk of complications.Among the long-term follow-ups after gastrectomy, gallstone is a common complication with a 7.4-40% prevalence [2][3][4][5] .The mechanism of gallstones after gastrectomy remains uncertain.It might be associated with the severed vagus nerve and anatomical changes, leading to impaired gallbladder contraction and changes in intestinal hormone [6,7] .These factors ultimately contribute to the alterations in bile composition, promoting gallstone formation postgastrectomy.
The survival time for gastric cancer after gastrectomy has increased due to early diagnosis, comprehensive perioperative treatment, and improved surgical technology [8,9] .However, gallstones after gastrectomy can potentially result in acute cholecystitis, which requires surgical intervention, otherwise it can affect the patient's quality of life.The anatomical changes and abdominal adhesions from gastrectomy heighten the likelihood of biliary tract injury in cholecystectomy, making cholecystectomy more difficult postgastrectomy.Consequently, it is crucial to investigate gallstone-related issues following gastrectomy to give valuable findings for prevention and therapy.
Current research on gallstones after gastrectomy is limited, especially in the presence of gallstones after a specific anastomotic technique in gastrectomy.Roux-en-Y reconstruction, a commonly employed anastomosis technique during gastrectomy, results in decreased secretion of gastric acid and pepsin, encourages gastric emptying, prevents alkaline reflux, and mitigates the risk of reflux gastritis [10] .We designed a retrospective cohort study to explore the incidence and risk factors related to gallstones after Roux-en-Y reconstruction gastrectomy in gastric cancer to complement the research gaps in the field.

Study design and participants
This study is a two-center, retrospective cohort study, divided into a distal gastrectomy group and total gastrectomy according to the extent of gastrectomy to investigate the incidences and potential risk factors of gallstones after Roux-en-Y reconstruction gastrectomy in gastric cancer.This study was complied with Strengthening the Reporting of Cohort Studies in Surgery (STROCSS) guideline [11] (Supplemental Digital Content 1, http:// links.lww.com/JS9/B815).
This study used data from patients who underwent surgical intervention for gastric cancer from January 2014 to December 2020 in the Department of General Surgery of the First Hospital of Lanzhou University and the Department of Gastric Surgery of the Gansu Wuwei Tumor Hospital.The applied exclusion criteria were as follows: (1) Not Roux-en-Y reconstruction; (2) a history of upper abdominal surgeries, such as gastrectomy and cholecystectomy; (3) preoperative gallbladder diseases, including gallstones, gallbladder polyps, cholecystitis; (4) a previous history of malignant tumors; (5) emergency or palliative surgeries; (6)  incomplete case data.
The study was approved by the ethics committee and registered at clinicaltrials.gov.

Surgical procedures
All patients underwent general anesthesia and radical gastrectomy, including resection of the primary lesion (either the entire stomach or the distal stomach), D1 or D2 standard Lymph node dissection, Roux-en-Y reconstruction, and postoperative nutritional support.In distal gastrectomy, 3/4 to 4/5 of the stomach was resected, the duodenal stump was closed, and the jejunum was severed 10-15 cm from the distal end of the Treitz ligament.The remnant stomach was anastomosed with the distal jejunum.The proximal jejunal was connected to the jejunal with located 45-60 cm below this gastrointestinal anastomosis sit.In cases of whole-stomach removal, the duodenal stump was closed, and the jejunum was severed 15-20 cm from the distal end of the Treitz ligament level, the esophagus was joined with the distal jejunum.The jejunal segment located 40 cm below this anastomosis point was linked to the proximal jejunal (Fig. 1).

Outcome
The primary outcome was gallstone after gastrectomy, with a follow-up period through October 2023.Gallstones after gastrectomy were defined as detected following gastrectomy in patients who had no gallstones before gastrectomy.Secondary outcomes encompassed bile duct stones, acute cholecystitis, and gallbladder polyps after gastrectomy.The confirmation of all outcomes was achieved through imaging.
Patients were reviewed monthly within 6 months of surgery, semi-annually after 6 months, and annually after 2 years.Abdominal ultrasonography, regarded as the gold standard for diagnosing gallstones, exhibits strong echoes within the gallbladder and demonstrates postsounding and movement in response to changes in body position.Computed tomography (CT) or MRI, primarily used for detecting metastatic disease, could also reveal the presence of gallstones.

Collection of covariables
Firstly, the gastrectomy range of the patients was collected, according to which the patients were divided into the distal gastrectomy group and the total gastrectomy group.Baseline data, such as sex, age, BMI, and comorbidities (hypertension, diabetes, hepatitis, fatty liver, and anemia), were systematically collected.Additionally, preoperative blood indicators, including hemoglobin (Hb), albumin (Alb), alanine aminotransferase (ALT), aspartate aminotransferase (AST), total bilirubin (TBIL), and direct bilirubin (DBIL), were assessed.Perioperative information, including mode of operation, whether hepatoduodenal ligament lymph node (No.12) dissection, whether blood transfusion, whether received neoadjuvant, postoperative pathological stage (TNM), and whether patients received at least one cycle of complete adjuvant chemotherapy were also recorded.We also collected complications after gastrectomy according to the Clavien-Dindo classification and included complications of grade II and above in our study [12,13] .

Sample size
This study was a retrospective cohort study design, with the experimental group being the total gastrectomy group and the

Baseline and perioperative characteristics
Between January 2014 and December 2020, 1558 patients who matched the inclusion criteria for surgical treatment of gastric cancer were assessed for eligibility.After rigorous screening procedures, 1027 patients were excluded from the study (Fig. 2).
The remaining patients comprised 513 and were classified into two groups based on the extent of gastrectomy: distal gastrectomy group (n = 201) and total gastrectomy group (n = 330).The follow-up deadline was October 2023.Table 1 displays the baseline and perioperative characteristics of the patients enrolled.
Statistical differences significantly differed between the groups concerning age, surgical method, and TNM.The proportion of patients with elderly (age ≥ 65 years), open surgery, and III stages was higher in the total gastrectomy group than in the distal gastrectomy group.No statistical differences in other characteristics were found between the two groups.

Primary outcome
During the study's median follow-up period of 67.89 (64.38-71.40)months, 170 cases (32.02%) developed gallstones, with 49 cases in the distal gastrectomy group and 121 cases in the total gastrectomy (Table 2).The occurrence of gallstones in patients who underwent total gastrectomy was considerably higher than in patients who underwent distal gastrectomy within 2 years postsurgery (31.52 vs. 20.90%,P = 0.003) (Fig. 3A).Within the first 2 years postgastrectomy, 145 gallstone cases were observed, constituting 85.29% of all gallstone cases after gastrectomy.Of these, 120 cases of gallstones were reported within the first year following gastrectomy, representing 70.59% of the overall incidence.Between 1 and 2 years after surgery, 25 cases (14.71%) were observed.Additionally, 25 cases of gallstones were reported 2 years following the gastrectomy, accounting for 14.71% of all gallstones.

Secondary outcome
Higher incidence of gallbladder polyps in the distal gastrectomy group than in the total gastrectomy group (6.97 vs. 2.42%, P = 0.011).There was no significant difference in bile duct stone and acute cholecystitis after gastrectomy between the distal gastrectomy group and the total gastrectomy group (Table 2).No significant differences were observed between the two groups regarding postoperative complications.

Post-PSM analysis
The 1:1 PSM analysis was performed between the two groups of patients to minimize the effect of bias in demographic and perioperative information.Ultimately, 344 patients were evaluated, with each subgroup comprising 172 (Table 4).The P values for all variables were more significant than 0.05, indicating no statistical difference in demographic and perioperative information between the two groups of patients.
The prevalence of gallstones after gastrectomy was 30.81% in the PSM cohort.The incidence of gallstones after total gastrectomy was significantly higher than in the distal gastrectomy group (36.05 vs. 25.58%,P = 0.036) (Table 5, Fig. 3B).There was no statistically significant difference between the two groups regarding postgastrectomy choledocholithiasis, acute cholecystitis, and gallbladder polyps.There was also no significant difference in postoperative complications.
Subgroup analyses of the PSM cohort showed an interaction between the surgical approach and extent of gastric resection in patients with gastric cancer on the effect of gallstones after gastrectomy (P = 0.008); Compared with distal gastrectomy, open surgery further increased the risk of gallstones after total gastrectomy.(HR 2.33; 95% CI: 1.48-3.66,P < 0.001) (Fig. 4).The relationship between postoperative complications (such as leakage and gastrointestinal obstruction) and gallstones after gastrectomy was analyzed using data from the PSM cohort, and no statistical significance was found (S-Fig.1, Supplemental Digital Content 2, http://links.lww.com/JS9/B816).

Discussion
In this study, the incidence of gallstones following gastrectomy was 32.02%, significantly surpassing the prevalence observed in the general population of Asian countries [14,15] .It was noted that a significant primarily of gallstones within 2 years following surgery, with which the outcomes of prior research aligned [16] .Findings from Cox regression analysis of the post-PSM cohort indicated a higher probability of gallstone following a total gastrectomy than a distal gastrectomy in Roux-en-Y reconstructive gastrectomy for gastric cancer.A significant risk factor for gallstones after gastrectomy, as also identified in a Korean study involving 47 752 patients, was total gastrectomy [17] .During a total gastrectomy, the vagal trunk is completely severed, resulting in the loss of hepatic branch function of the vagus nerve.The hepatic branch, originating from the anterior trunk, plays a critical role in biliary function.Damage to the hepatic branch during gastrectomy can lead to impaired gallbladder contraction, the accumulation of bile salts, cholestasis, and eventually the formation of gallstones [6,18] .
A clinical investigation involving 467 early-stage gastric cancer patients confirmed that preserving the hepatic branch of the vagus nerve during laparoscopic distal gastrectomy is recommended to reduce postoperative gallstones [19] .The Japanese Gastric Cancer Treatment Guidelines 2021 (6th edition) also advocate for preserving both the hepatic and abdominal branches of the vagus nerve, as it was believed that this approach mitigates the incidence of gallstones postoperatively, facilitates early recovery and improves patients' quality of life [20] .Total gastrectomy in Roux-en-Y reconstructive gastrectomy for gastric cancer patients in this study exhibited a higher prevalence of postoperative gallstones than distal gastrectomy.Since total gastrectomy completely severed the vagus nerve, while distal gastrectomy severed the vagus nerve to a lesser extent, the effect of the degree of vagus nerve severed on postoperative gallstones can also be confirmed laterally in this study.Thus, preserving the vagus nerve during gastrectomy in gastric cancer has a significant preventive function against postoperative gallstones.
According to a study of 1284 patients, it was found that overweight and obese individuals (BMI ≥ 23 kg/m 2 ) had an elevated risk of gallstone formation following gastrectomy [21] .It was also denoted in our research that a high BMI exacerbates the formation of gallstones postoperatively.The primary pathophysiological mechanism that drives gallstone formation is the hypokinesis of the gallbladder, a condition that inhibits gallbladder emptying, causing cholestasis and bile salt deposition, thereby paving the way for gallstone development [22] .This mechanism can be observed in obese individuals with significant  weight loss in men [23] .The association between high BMI and postoperative gallstone formation could be due to the increased visceral and omental fat content in overweight and obese patients, inducing more significant postoperative weight loss.Besides, obesity is associated with the formation of gallstones, as it enhances cholesterol synthesis and excretion in the liver, leading to cholesterol supersaturation in the gallbladder, and the formation of cholesterol stones [24] .
We also observed a significant increase in gallstone incidence among female patients postgastrectomy.Possible explanations include females' inherent predisposition to gallstone formation, or that our study focused on a population undergoing Roux-en-Y reconstruction, or it may be due to the small proportion of women in our included population [24] .Therefore, there is a need to further investigate the relationship between gender and gallstones after gastrectomy.A retrospective study of 805 patients found a direct correlation between the extent of lymph node dissection and the incidence of gallstones following gastrectomy [25] .Patients who underwent D2 or D2 + lymph node dissection had an increased risk of developing symptomatic gallstones postgastrectomy, potentially requiring revisional cholecystectomy.However, due to variations in D2 lymph node dissection scope between total and distal gastrectomy, our study only examined the influence of hepatoduodenal ligament lymph node (No.12 lymph node) on gallstone formation postoperatively.The results indicated that No.12 lymph node dissection was an independent risk factor for developing gallstones after gastrectomy.The potential mechanism may involve edema, inflammation, and adhesions surrounding the bile duct after hepatoduodenal ligament lymph node dissection, which leading to the obstruction of bile outflow and the concentration of bile in the gallbladder, which may promote gallstone formation [26] .
A study of 561 patients found that those not receiving adjuvant chemotherapy had a higher prevalence of postoperative gallstones [27] .On the contrary, our research indicated that adjuvant chemotherapy might increase gallstone risk after  gastrectomy.Postoperative adjuvant chemotherapy is a valuable approach to lowering the risk of tumor recurrence and enhancing survival rates among patients with high-risk tumors following surgical intervention.Adjuvant chemotherapy could be related to changes in intestinal flora, which plays a crucial role in gallstone formation [28][29][30][31] .Due to the unclear relationship between adjuvant chemotherapy and gallstones after gastrectomy for gastric cancer, further research is needed.
In the post-PSM cohort, subgroup analysis revealed that open surgery increased further the risk of gallstones after total gastrectomy.This may be related to the complete severing of the vagus nerve in open total gastrectomy as well as postoperative adhesions in the surrounding tissues, which in turn have a greater impact on the contractile function of the gallbladder, among other things.Diabetes is a potential risk factor for gallstone development following gastrectomy with gastric cancer in two cohort studies [32,33] .However, our study did not find a correlation between preoperative comorbidities (including hypertension, diabetes, and others) and the formation of gallstones after gastrectomy.Further research is necessary to understand the relationship between preoperative comorbidities and gallstone development after gastrectomy.We categorized postgastrectomy complications according to Clavien-Dindo and examined potential associations between leakage, gastrointestinal obstruction, and gallstones after gastrectomy in a post-PSM cohort using a log-rank test.The results showed no association, which may be due to the limited sample size.More extensive studies with larger sample sizes are needed to determine the association.
Prevention of gallstones after gastrectomy consists mainly of postoperative prophylactic use of ursodeoxycholic acid and prophylactic cholecystectomy.Prophylactic use of ursodeoxycholic acid after gastrectomy reduces the incidence of gallstones after gastrectomy and the likelihood of cholecystectomy [34,35] .In a study recommended that cholecystectomy be performed concurrently with gastrectomy in elderly patients with Roux-en-Y reconstruction [36] .Additionally, a study of 2383 patients undergoing laparoscopic sleeve gastrectomy for weight loss found that concurrent cholecystectomy was safe and necessary for symptomatic gallstones, but prophylactic cholecystectomy was deemed unnecessary in the absence of gallstones [37] .It has also been suggested that individualized prophylactic cholecystectomy for gallstones after gastric cancer surgery will be the focus of future research [38] .Prophylactic cholecystectomy during gastrectomy for gastric cancer remains controversial.
It is worth noting that Prophylactic cholecystectomy is performed to avoid repeat cholecystectomy after gastrectomy due to symptomatic gallstones.However, in the post-PSM cohort of this study, the incidence of gallstones after gastrectomy was 30.81%, while symptomatic gallstones (acute cholecystitis) accounted for only 6.6% of gallstones (7/106).Therefore, preservation of the gallbladder, along with avoidance of vagal nerve injury during gastrectomy and postoperative prophylactic use of ursodeoxycholic acid, may be a more favorable option to reduce the development of symptomatic gallstones in patients with high-risk factors.
There are limitations in the present study.First, some patients underwent only CT during the follow-up period, which could have led to negative stones undetected and affected the overall incidence of stones.Second, this study is retrospective, and bias may exist.In a subsequent multicenter prospective study, a larger patient cohort will be utilized to assess the incidence and associated risk factors of gallstones after Roux-en-Y reconstructive gastrectomy in gastric cancer, as well as further investigate preventive measures.

Conclusion
Gallstones occurred in 32.02% of patients after Roux-en-Y reconstruction gastrectomy in gastric cancer and primarily within 2 years after gastrectomy.Females, BMI ≥ 23 kg/m 2 , total gastrectomy, No.12 lymph node dissection, and adjuvant chemotherapy were risk factors for gallstones after Roux-en-Y reconstructive gastrectomy.Patients with the above risk factors should close follow-up after surgery to avoid the development of symptomatic gallstones.

Figure 2 .
Figure 2. Flow chart of inclusion and exclusion.

Figure 3 .
Figure 3. Cumulative incidence of gallstones after gastrectomy.(A) Cumulative incidence of gallstones after distal gastrectomy and total gastrectomy (P = 0.003, Log Rank test); (B) Cumulative incidence of gallstones after distal gastrectomy and total gastrectomy in PSM cohort (P = 0.035, Log Rank test).

Figure 4 .
Figure 4. Forest plot for subgroup analysis of gallstones after gastrectomy in the PSM cohort.

Table 1
Baseline and perioperative information in the distal gastrectomy and total gastrectomy groups before propensity score matching.

Table 2
Outcomes and postoperative complications in the distal gastrectomy and total gastrectomy groups before propensity score matching.

Table 3
Cox regression analysis of gallstones after Roux-en-Y reconstructive gastrectomy in gastric cancer before propensity score-matched.

Table 4
Baseline and perioperative information in the distal gastrectomy and total gastrectomy groups after propensity score matching.

Table 5
Outcomes and postoperative complications in the distal gastrectomy and total gastrectomy groups after propensity score matching.

Table 6
Cox regression analysis of gallstones after Roux-en-Y reconstructive gastrectomy in gastric cancer after propensity score-matched.