Using low concentration sodium hypochlorite to improve colorectal surgical specimen lymph node harvest

Lymph node (LN) retrieval is a critical procedure to determine the pathological stage and adjuvant therapy for colorectal cancer. The present study aimed to recommend a novel method by using sodium hypochlorite to improve colorectal surgical specimen LN harvest. Dissolving time of mesenteric LNs and fat tissue was firstly investigated in different concentrations of sodium hypochlorite. In the sodium hypochlorite group, 65 patients with colorectal cancer who underwent curative surgery were included. After standard manual gross dissection, the mesenteric tissue was subsequently immersed in 1% sodium hypochlorite for ~30 min, and then manual dissection was again applied for additional LN harvest. In the manual method group, 68 patients with colorectal cancer were selected and only manual dissection method was applied for LN harvest. The number of LNs in both groups were recorded for each case. Sodium hypochlorite could dissolve fat tissue significantly faster than LNs and the low concentration sodium hypochlorite had the maximum dissolving time difference between fat tissue and LNs (P<0.001). After sodium hypochlorite treatment, more LNs were identified when compared with the manual dissection method (28.2±12.1 vs. 16.5±8.7; P=0.010), whereas the number of positive LNs had no significant statistical difference between the two groups (P=0.181). After sodium hypochlorite immersion, 818 additional LNs (12.5±4.8 per case) were identified and LNs ≤2 mm were 58.4% (478/818). Moreover, 16 additional metastatic LNs were found in 10 patients. A total of 7 of them were upstaged, including 2 initially N0 cases. Using sodium hypochlorite at low concentrations may be the most simple, rapid, cost-saving, nontoxic and effective technique to improve LN harvest in colorectal carcinoma specimens so far. This method should be used routinely regardless of whether the number of LNs is <12 or not.