Submucousal injection of Carbon nanoparticles preoperatively improves lymph node staging accuracy in rectal cancer following neoadjuvant chemoradiotherapy

Yanan Wang, PhD¹, Haijun Deng, PhD¹, Hongyuan Chen, MD², Hao Liu¹, Jun Yan, PhD¹, Qi Xue¹, Hao Chen¹, Guoxin Li¹. ¹Department of General Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China, ²Department of Gastrointestinal Surgery, Fujian Provincial Hospital, Fuzhou, China

Purpose: To evaluate the association between the number of node harvested and the rate of node positivity, and the effect of carbon nanoparticles on improving lymph node detection and staging accuracy in patients who received neoadjuvant chemoradiotherapy followed by curative resection.

Methods: One hundred and fifty-two patients with rectal cancer treated with neoadjuvant chemoradiaothepapy and curative resection were included for analysis. Of these, 45 patients underwent carbon nanoparticles injection one day before surgery (carbon nanoparticles group), while the others underwent surgery only (control group). Logistic regression model was used to explore the relationship between the number of lymph node retrieved and the node positivity. The number and positivity of lymph node harvested were compared between the carbon nanoparticles group and the control group.

Results: The proportion of patients with node-positive raised gradually from 11.3% in patients with 1-4 nodes harvested to 33.4% in patients with 16-44 nodes harvested. Multivariate logistic regression analysis revealed that the number of lymph node harvested was an independent risk factor for the node positivity (6-9 vs. 1-5: OR=5.19, 95%CI=1.00-26.99, p=0.050; 10-16 vs. 1-5: OR=10.56, 95%CI=2.17-51.47, p=0.004; 16-44 vs. 1-5: OR=6.89, 95%CI=6.42-33.54, p=0.017). The mean number of lymph node harvested was 21.2 in carbon nanoparticles group and 8.9 in the control group (p=0.002). The percentage of patients with positive lymph node increased from 21.5% in the control group to 31.1% in carbon nanoparticle group (p=0.038).

Conclusions: The lymph node positivity is significantly associated with the number of lymph node harvested in patients with rectal cancer following neoadjuvant therapy. Submucousal injection of carbon nanoparticles preoperatively could increase the number of lymph node retrieval and the rate of node positivity.

Keyword: Carbon nanoparticles, Rectal cancer, Lymph node, Neoadjuvant chemoradiotherapy