Novel management indications for conservative treatment of chylous ascites after gastric cancer surgery

BACKGROUND Chylous ascites(CA) presents a challenge as a relatively common postoperative complication in gastric cancer(GC). Primary conservative therapy involved total parenteral nutrition, continuous low-pressure drainage, somatostatin, and a lowfat diet. Drainage tube(DT) clamping has been presented as a potential alternative conservative treatment for GC patients with CA.AIM To propose novel conservative treatment strategies for CA following GC surgery.METHODS The data of patients with CA after GC surgery performed at the Fudan University Shanghai Cancer Center between 2006 and 2021 were evaluated retrospectively.RESULTS 53 patients underwent surgery for GC and exhibited postoperative CA during the study period. Postoperative hospitalization and time of DT removal showed a significant positive association(R~2 = 0.979, P < 0.001). We further observed that delayed DT removal significantly extended the total and postoperative hospitalization, antibiotic usage duration, and hospitalization cost(postoperative hospitalization: 25.8 d vs 15.5 d, P < 0.001;total hospitalization: 33.2 d vs 24.7 d, P < 0.01;antibiotic usage duration: 10.8 d vs 6.2 d, P < 0.01;hospitalization cost: ￥9.2 × 104vs ￥6.5 × 104, P < 0.01). Multivariate analysis demonstrated that postoperative infection and antibiotic usage were independent factors for delayed DT removal.Furthermore, DT removal times were shorter in seven patients who underwent DT clamping(clamped DT vs normal group, 11.8 d vs 13.6 d, P = 0.047;clamped DT vs delayed group, 13.6 d vs 27.4 d, P < 0.001). In addition, our results indicated that removal of the DT may be possible after three consecutive days of drainage volumes less than 300 mL in GC patients with CA.CONCLUSION Infection and antibiotic usage were vital independent factors that influenced delayed DT removal in patients with CA. Appropriate standards for DT removal can significantly reduce the duration of hospitalization. Furthermore, DT clamping might be a recommended option for conservative treatment of postoperative CA.

Microencapsulated tumor assay:Evaluation of the nude mouse model of pancreatic cancer

AIM: To establish a more stable and accurate nude mouse model of pancreatic cancer using cancer cell microencapsulation. METHODS: The assay is based on microencapsulation technology, wherein human tumor cells are encapsulated in small microcapsules (approximately 420 μm in diameter) constructed of semipermeable membranes. We implemented two kinds of subcutaneous implantation models in nude mice using the injection of single tumor cells and encapsulated pancreatic tumor cells. The size of subcutaneously implanted tumors was observed ona weekly basis using two methods, and growth curves were generated from these data. The growth and metastasis of orthotopically injected single tumor cells and encapsulated pancreatic tumor cells were evaluated at four and eight weeks postimplantation by positron emission tomography-computed tomography scan and necropsy. The pancreatic tumor samples obtained from each method were then sent for pathological examination. We evaluated differences in the rates of tumor incidence and the presence of metastasis and variations in tumor volume and tumor weight in the cancer microcapsules vs single-cell suspensions. RESULTS: Sequential in vitro observations of the microcapsules showed that the cancer cells in microcapsules proliferated well and formed spheroids at days 4 to 6. Further in vitro culture resulted in bursting of the membrane of the microcapsules and cells deviated outward and continued to grow in flasks. The optimum injection time was found to be 5 d after tumor encapsulation. In the subcutaneous implantation model, there were no significant differences in terms of tumor volume between the encapsulated pancreatic tumor cells and cells alone and rate of tumor incidence. There was a significant difference in the rate of successful im- plantation between the cancer cell microencapsulation group and the single tumor-cell suspension group (100% vs 71.43%, respectively, P = 0.0489) in the orthotropic implantation model. The former method displayed an obvious advantage in tumor mass (4th wk: 0.0461 ± 0.0399 vs 0.0313 ± 0.021, t = -0.81, P = 0.4379; 8th wk: 0.1284 ± 0.0284 vs 0.0943 ± 0.0571, t = -2.28, respectively, P = 0.0457) compared with the latter in the orthotopic implantation model. CONCLUSION: Encapsulation of pancreatic tumor cells is a reliable method for establishing a pancreatic tumor animal model.