Chylous Ascites After Rectal Cancer Surgery: Incidence, Prognostic Impact, and Surgical Approach Considerations
Chylous ascites, characterized by the accumulation of milky lymphatic fluid in the peritoneal cavity, is a rare but clinically significant complication following abdominal surgery. While it is generally manageable through conservative measures, its long-term implications for cancer recurrence and survival remain understudied, particularly in the context of rectal cancer surgery. This article explores the incidence, risk factors, and prognostic implications of chylous ascites in patients undergoing neoadjuvant chemoradiotherapy (CRT) followed by rectal cancer resection, with a focus on surgical approaches and oncological outcomes.
Background and Clinical Significance
Chylous ascites arises from the disruption of lymphatic channels during surgery, leading to the leakage of triglyceride-rich fluid. Though uncommon in colorectal surgery (reported incidence: 1.0%–7.7%), it poses nutritional, immunological, and metabolic challenges due to the loss of proteins, lipids, and lymphocytes. Prior studies have highlighted its higher incidence after pancreatic or retroperitoneal surgeries (up to 11%), but data specific to rectal cancer are limited. The potential for chylous ascites to facilitate peritoneal dissemination of cancer cells via leaked lymphatic fluid has been hypothesized, though evidence remains conflicting. This study addresses these gaps by evaluating the incidence, management, and long-term outcomes of chylous ascites in a large cohort of patients with locally advanced rectal cancer (LARC) treated with neoadjuvant CRT followed by surgery.
Study Design and Patient Cohort
A retrospective analysis was conducted on 898 patients with LARC (clinical stages T3, T4, or TxN+) treated at a tertiary center in China between 2010 and 2018. All patients received neoadjuvant CRT followed by curative-intent surgery, including total mesorectal excision (TME) or partial mesorectal excision. Exclusion criteria included metastatic disease, incomplete recurrence data, or synchronous malignancies. Chylous ascites was diagnosed based on milky drainage fluid with triglyceride levels >110 mg/dL or confirmed chylomicrons.
Surgical Techniques and Postoperative Management
Three surgical approaches were compared: open surgery, laparoscopic surgery, and robotic-assisted surgery. D3 lymph node dissection, involving high ligation of the inferior mesenteric artery (IMA) and removal of regional lymph nodes, was routinely performed. Postoperatively, patients received conservative management for chylous ascites, including a low-fat diet, total parenteral nutrition (TPN), and somatostatin analogs to reduce lymphatic flow. Surgical intervention was not required in any case.
Key Findings: Incidence and Risk Factors
Chylous ascites occurred in 3.8% (34/898) of patients, with a median onset of 4 days postoperatively. The incidence varied significantly by surgical approach:
- Robotic surgery: 6.9% (6/86)
- Laparoscopic surgery: 4.2% (26/618)
- Open surgery: 1.0% (2/192)
The higher incidence in minimally invasive procedures (robotic and laparoscopic) may relate to technical factors, such as incomplete sealing of lymphatic-rich tissues near the IMA due to reduced tactile feedback in robotic systems. Younger age (mean 52.4 vs. 56.4 years; P=0.043) and a higher lymph node yield (15.6 vs. 12.8 nodes; P=0.009) were also associated with chylous ascites, suggesting aggressive lymphadenectomy as a contributing factor.
Short-Term Outcomes and Management
Patients with chylous ascites experienced a 3-day prolongation of postoperative hospitalization (11.9 vs. 8.9 days; P=0.017). The average drainage volume peaked at 262 mL/day and gradually decreased to 102 mL/day by the time of drain removal. Conservative therapy was effective in all cases, with somatostatin initiated early to reduce chyle production. No differences were observed in other complications, such as anastomotic leakage, wound infection, or pneumonia.
Long-Term Oncological Outcomes
The 5-year recurrence-free survival (RFS) rate was significantly lower in the chylous ascites group (64.5% vs. 79.9%; P=0.007), even after propensity score matching to control for confounders like age, tumor stage, and surgical approach. Overall survival (OS) also showed a nonsignificant trend toward poorer outcomes in the chylous ascites group (70.7% vs. 83.3%; P=0.066). Multivariate analysis confirmed chylous ascites as an independent negative prognostic factor for RFS (hazard ratio [HR]=3.038; P<0.001), alongside advanced ypT stage, ypN stage, and neural invasion.
Patterns of Recurrence
While overall recurrence rates did not differ between groups, peritoneal metastasis occurred more frequently in the chylous ascites cohort (5.9% vs. 1.6%; P=0.120). This aligns with the hypothesis that lymphatic fluid leakage may disseminate cancer cells intraperitoneally. However, other sites of metastasis (liver, lung, bone) showed no significant differences.
Mechanistic Insights and Clinical Implications
The study highlights two critical mechanisms linking chylous ascites to poor prognosis:
- Peritoneal Dissemination: Leaked lymphatic fluid may carry viable tumor cells, increasing the risk of peritoneal metastases.
- Delayed Adjuvant Therapy: Prolonged hospitalization (though only 3 days longer) might delay adjuvant chemotherapy, though this was not explicitly measured.
The higher incidence after robotic and laparoscopic surgeries underscores the need for meticulous technique during minimally invasive procedures. Surgeons are advised to ensure thorough coagulation of lymphatic tissues near the IMA and its branches to minimize leakage.
Limitations and Future Directions
The retrospective design and small sample size of chylous ascites cases limit causal inferences. Variations in diagnostic criteria for chylous ascites across studies also complicate comparisons. Prospective studies with standardized protocols are needed to validate these findings and explore preventive strategies, such as intraoperative lymph node mapping or fibrin sealants.
Conclusion
Chylous ascites, though rare, is a consequential complication of rectal cancer surgery, particularly after robotic and laparoscopic approaches. Its association with reduced recurrence-free survival underscores the importance of preventive measures during surgery. Clinicians should prioritize meticulous lymphatic sealing in minimally invasive procedures and monitor high-risk patients for early signs of recurrence. Further research is warranted to elucidate the biological mechanisms linking chylous leakage to peritoneal dissemination and to refine therapeutic strategies.
doi.org/10.1097/CM9.0000000000001809
Was this helpful?
0 / 0