Assessment of Lymph Node Metastasis in Elderly Patients with Colorectal Cancer by Sentinel Lymph Node Identification Using Carbon Nanoparticles

Purpose: To evaluate the value of sentinel lymph node (SLN) identification using carbon nanoparticles in abdominal lymph node metastasis in elderly (>60 years old) patients with colorectal cancer.

Methods: Eighty patients admitted at Weihai Second Municipal Hospital affiliated to Qingdao University from November 2014 to February 2017 were selected and divided into the control group (n=40) and the observation group (n=40) using the random number method. The control group was treated with surgery, while the observation group was administered carbon nanoparticle tracer for intraoperative dye detection and positioning; the first to four black-stained lymph nodes were marked as SLN, then radical surgery for colorectal cancer was performed. Pathological examination of intraoperative specimens was performed to assess the effect of SLN in the abdominal lymph node metastasis.

Results: There were no statistically significant differences in the metastasis rate and lymph node metastasis rate between the two groups (p>0.05). The total number of lymph nodes and the number of lymph nodes with micrometastases (<2mm) in the observation group were larger than those in the control group (p<0.05); the ratio of fewer than 12 lymph nodes in the observation group was lower than that in the control group (p<0.05). In the observation group, 8 out of 40 cases had lymph node metastasis, the detection rate of SLN using carbon nanoparticles was 92.50%, the accuracy rate 94.59%, the specificity of diagnosis 87.50%, the false negative rate 12.50% and the negative predictive value 21.88%. There was no statistically significant difference in the metastasis rate of black-stained and non-black-stained lymph nodes in the observation group (p>0.05). The blackstained rate of micro lymph nodes was higher than the total black-stained rate (p<0.05); the rate of micro lymph node metastasis was lower than that of lymph node metastasis >5mm (p<0.05).

Conclusion: Preoperative SLN examination can evaluate the abdominal lymph node status in elderly patients with colorectal cancer, which is simple and accurate and can guide the clinical treatment, so it is worthy of popularization and application.