Lymph node retrieval after colorectal cancer surgery: a comparative study of the efficacy between the conventional manual method and a new fat dissolution method

Enzymatic Fat Dissolution Improves Detection of Small Lymph Nodes in Colon Cancer Surgery

Background Accurate lymph node evaluation is essential for staging colon cancer and guiding postoperative treatment decisions. In this study, we compared the efficacy of a simple enzymatic fat dissolution method with the conventional method for lymph node sampling from specimens after colon cancer surgery. Methods We enrolled 58 patients who underwent elective laparoscopic surgery for colon adenocarcinoma between May 2018 and May 2021 at Fukuoka University Hospital in Fukuoka, Japan. The specimens from these patients were treated using fat dissolution and were compared with specimens from 58 patients for which conventional manual palpation was used. Results A significantly greater number of lymph nodes were detected by the fat dissolution method compared with the conventional method (average per patient, 27.5 vs. 22.6, P = 0.02). In particular, the between-group difference was significant for lymph nodes measuring <5 mm (average per patient, 26.1 vs. 20.9; P = 0.01). Multivariate analysis showed that, compared with the conventional method, the fat dissolution method was significantly associated with the identification of lymph node metastasis. The positive rate of lymph nodes ≥10 mm in diameter was markedly higher along the inferior mesenteric artery than the ileocolic artery (100% vs. 52.6%). Conclusions The use of the fat dissolution method led to an increase in the number of small lymph nodes detected. Rates of metastasis according to lymph node size may depend on the lymph node station.

A new fat-dissociation method to detect lymph nodes in colorectal cancer: a prospective randomized study

Histological examination of the lymph nodes (LNs) is crucial to determine the colorectal cancer (CRC) stage. We previously reported a new fat-dissociation method (FM) to detect LNs from surgically resected mesentery. This study aimed to examine the effectiveness of FM compared with that of conventional palpation method (PM) in CRC. This single-center, open-label, randomized controlled study was performed at Osaka International Cancer Institute in Japan in 2014. Randomization was performed using a computer-generated permuted-block sequence. Patients were stratified by surgical procedures and the LN dissection area. The primary endpoint was the time required for LN identification. The secondary endpoint was the number of LNs and 5-year cancer-specific survival. The 130 enrolled patients were randomly assigned in a 1:1 ratio to the FM and the PM groups. LN identification times were 45 (range 15-80) and 15 (range 7-30) minutes in the PM and the FM groups, respectively (P < 0.001). In the PM group, body mass index and identification time were correlated (P = 0.047). The number of LN which could be examined pathologically was 16 (range 2-48) and 18 (range 4-95) in the PM and FM groups, respectively (P = 0.546). In right-sided CRC, the number of LNs was higher in the FM group than in the PM group (P = 0.031). Relapse-free survival rates and cancer-specific survival rates did not differ between the groups. In conclusion, FM reduced the time required for LN detection without reducing the number of detected LNs, making it is a useful method to detect LNs in surgical specimens.

Efficacy of the fat-dissociation method for nodal harvesting in gastric cancer

BACKGROUND

There is an increased need for accurate staging for gastric cancer treatment. Consequently, it is necessary to carefully examine all dissected lymph nodes for precise staging. Recently, the fat-dissociation method has been developed as a quick and accurate method for harvesting dissected lymph nodes of colorectal cancer cases.

AIM

To investigate the usefulness of the fat-dissociation method for harvesting dissected lymph nodes of gastric cancer cases.

METHODS

Fifty-six resected specimens from gastric cancer patients who underwent standard curative gastrectomy and lymph node dissection at our hospital were used. Group 2 lymph nodes were separated from each specimen, and the remaining adipose tissue containing the group 1 lymph nodes was used. Some resected specimens were subjected to the fat-dissociation method. One vial of Imofully® was dissolved in 50 mL of saline and injected into the tissue. The tissue was incubated for 1 h and the dissolved fat was removed. Subsequently, the nodes were identified, picked up with scissors, and mapped. The number of nodes in each lymphatic compartment and duration of lymph node harvest and mapping were compared.

RESULTS

The fat-dissociation method was used for 24 samples, while the conventional dissection method was used for 32 samples. The total number of harvested lymph nodes was 45.9 in the fat dissociation group and 44.3 in the control group, and there was no significant difference between the two groups. There were also no significant differences in the number of lymph nodes between the two groups based on a comparison of the lymphatic compartments. However, the total median duration of the fat-dissociation method was 38.2 min, reflecting a reduced duration of approximately 60 min compared to the control group.

CONCLUSION

Based on our results, the fat-dissociation method is effective in shortening the duration of lymph node harvest in gastric cancer surgery.