Epithelial ovarian cancer (EOC) is the most common ovarian malignancy. The 2018 International Federation of Gynecology and Obstetrics (FIGO) guideline recommended selective lymphadenectomy of the pelvic and para-aortic lymph nodes as part of the staging surgery for early-stage ovarian cancer. The 2019 version 1 edition of the National Comprehensive Cancer Network guidelines recommended that surgical treatment of EOC should include the para-aortic lymph node at least to the level of the inferior mesenteric artery, preferably that of the renal vessels. However, this radical treatment significantly increased the incidence of nerve and vascular injuries and intra-operative blood loss, as well as the incidence of chylous leakage, lymphatic leakage, and lymphedema. The most important risk factor associated with post-operative chylous leakage is that the intra-operative lymphatic vessels are not well exposed. Currently, research on lymphangiography in ovarian cancer surgery is mainly focused on sentinel lymph node (SLN) mapping and the prevention of chylous leakage by intra-operative chylous tube imaging. In this study, we presented our experience with the use of pre-operative oral peanut oil to identify the chylous tubes in the abdominal aortic region and to explore a new method of preventing post-operative chylous leakage.
This study was approved by the Ethics Committee of the Second Affiliated Hospital of Zhengzhou University (2020009). We retrospectively analyzed the clinical data of 103 patients with ovarian cancer who underwent para-aortic lymphadenectomy up to the renal vessels and pelvic lymphadenectomy, performed by the same group of doctors between January 2017 and December 2019. After obtaining informed consent, 52 cases were administered 60 mL of pre-operative oral peanut oil 10 h before surgery, while 51 cases were not administered oral peanut oil as the control group. The diagnostic criteria for chylous leakage were as follows: (1) post-operative abdominal drainage fluid is milky or chylous; (2) triglyceride ≥110 mg/dL (1.2 mmol/L); (3) daily drainage volume ≥200 mL; and (4) microbial culture and leucocyte testing rule out infection.
The average age of the 103 patients was 52.5 ± 8.8 years and the average body mass index was 24.15 ± 3.15 kg/m2. The histological types were serous carcinoma in 67 cases (65.05%), mucinous carcinoma in five cases (4.85%), clear cell carcinoma in 12 cases (11.65%), endometrioid carcinoma in 18 cases (17.48%), and carcinosarcoma in one case (0.97%). According to the FIGO guidelines, the surgical pathological staging was as follows: stage I in three patients (2.91%), stage II in 19 patients (18.45%), stage III in 71 patients (68.98%), and stage IV in ten patients (9.71%). The mean number of dissected pelvic and para-aortic lymph nodes was 25.77 ± 11.00 and 15.02 ± 8.57, respectively. Thirty-three patients underwent hyperthermic intraperitoneal chemotherapy. No statistically significant difference was found between the two groups in the aforementioned parameters. The difference in the incidence of chylous leakage was statistically significant, being significantly higher in the control group than in the oral peanut oil group (15.69% [8/51] vs. 3.85% [2/52], P = 0.042). The mean time of chylous leakage occurrence in these ten cases was 6.02 ± 2.35 days after surgery. Histologic types were as follows: eight cases of high-grade serous carcinoma, one case of carcinosarcoma, and one case of clear-cell carcinoma.
After taking 60 mL of peanut oil before surgery, the surface of the small intestine could be seen as a white grid or linear distribution of capillary lymphatic vessels [Figure 1A], and all the intestinal trunk was white in the abdominal aorta area [Figure 1B]. The intra-operative lymphatic vessel development rate was 98.08% (51/52). Intestinal trunk and affiliated lymphatic vessels distribution characteristics were as follows: chylous tubes distribution in the left side of the abdominal aorta and inferior mesenteric artery, 17.31% (9/52); lower part of the left renal vein, above the inferior mesenteric artery, 86.54% (45/52); the surface of the abdominal aorta, lower part of duodenal levels, 73.08% (38/52); and 5.77% (3/52) of patients had a variation of chylous tubes across the surface of the abdominal aorta and inferior vena cava, extending to the inferior vena cava on the right side of the pelvic course. In the case of intra-operative lymphatic drainage of milky white fluid, ligation or electrocoagulation was performed. Hemolok clamping, local spraying of biological protein glue or packing of absorbable materials was also performed.
The specific occurrence of lymphatic or chylous leakage mainly depends on the anatomical site of the lymphatic vessel injury. After absorption of fatty acids, glycerol, and glycerate by the villous epithelium of the small intestine to synthesize fat particles, they mainly enter the lymphatic capillaries, converge to form the intestinal trunk and then flow into the cisterna chyli. Chylous leakage may occur when the intestinal trunk is damaged. Chylous ascites lead to the loss of proteins and lymphocytes, which in turn leads to a series of mechanical, nutritional, and immune problems. After 1 to 3 days of intestinal preparation and cleansing before surgery, the lymphatic fluid of the intra-operative chylous tube was colorless and transparent, and the chylous tube pressure was lower. Therefore, it was difficult to visually identify the injury site of the chylous tubes. After oral administration of peanut oil before the operation, the intestinal trunk and its associated lymphatics appeared milky white with the absorption of fatty acids by the villous epithelium of the small intestine. Regarding the distribution, most of the chylous tubes were distributed in the area above the level of the inferior mesenteric artery. Therefore, the incidence of chylous leakage after para-aortic lymphadenectomy up to the inferior mesenteric artery or the renal vessel may also be different.
In summary, during para-aortic lymphadenectomy of ovarian cancer, pre-operative oral peanut oil could facilitate the identification of the intestinal trunk, which has a great effect on the prevention of chylous leakage after para-aortic lymphadenectomy and is worth promoting. Further prospective studies of the combination of chylous tube imaging and SLN mapping to specifically narrow the surgical scope and reduce the relative complications of ovarian cancer are warranted.
Conflicts of interest
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