A Multi-Center Study of Using Carbon Nanoparticles to Track Lymph Node Metastasis in T1-2 Colorectal Cancer

Jun Yan, MD, Fangqin Xue, MD, Hui Zhang, MD, Gang Chen, MD, Jianping Lu, MD, Lisheng Cai, MD, Mingzhi Cai, MD, Gao Xiang, MD, Yunfeng Hong, MD, Wenbo Chen, MD, Guoxin Li, MD. Department of General Surgery, Nanfang Hospital, Southern Medical University.

Background:

There are approximately 10 percent patients with lymph node metastasis in T1 colorectal cancer and approximately 20 percent patients with lymph node metastasis in T2 colorectal cancer. How to identify whether T1-2 colorectal cancer have lymph node metastases is a crucial problem in clinic. The purpose of this study was to evaluate the feasibility of using carbon nanoparticles to track lymph node metastasis in T1-2 colorectal cancer.

Methods:
A multi-center study was performed between July 2012 and September 2013. Seventy six patients with T1-2 colorectal cancer identified by pre-op endoscopic ultrasonography were recruited. One milliliter Carbon nanoparticles suspension, which was approved by Chinese Food and Drug Administration, was injected around cancer. Laparoscopic radical colorectomy with D2 (T1 cancer) or D3 (T2 cancer) lymph node dissection was performed. Carbon nanoparticles dyed lymph nodes were identified from all dissected lymph nodes, and pathology confirmed whether lymph nodes have cancer metastasis and the accuracy of carbon nanoparticles dyed lymph nodes as sentinel lymph node in T1-2 colorectal cancer.

Results:
There were 21 patients with T1 colorectal cancer and 55 patients with T2 cancer underwent surgery. Carbon nanoparticles could clearly show local lymph nodes, which were black-dyed under laparoscopy (Fig. 1A, 1B). Two patients (9.52%) had lymph node metastasis in 21 patients with T1 colorectal cancer, and 10 patients (18.18%) had lymph node metastasis in 55 patients with T2 colorectal cancer. In pathology, carbon nanoparticles were seen in lymphatic vessels (Fig. 1C), and lymphoid sinus (Fig. 1D, 1E) and macrophage (Fig. 1F) in lymph nodes. No other lymph node had cancer metastasis when carbon nanoparticles black-dyed lymph nodes were negative. When lymph nodes had cancer metastasis, carbon nanoparticles were seen around cancer cells in lymph nodes (Fig. 1G-1I).

Conclusions:
It is feasible to use carbon nanoparticles to track lymph node metastasis in T1-2 colorectal cancer. Carbon nanoparticles black-dyed lymph node plays a role as sentinel lymph node in T1-2 colorectal cancer.

Key words:
Carbon nanoparticles; Sentinel lymph node; Lymph node metastasis; T1-2 colorectal cancer; Multi-center study.