A multi-center study of using carbon nanoparticles to track lymph node metastasis in T1-2 colorectal cancer.

BACKGROUND: How to identify whether T1-2 colorectal cancers have lymph nodes metastases pre-op or intra-op is a crucial problem in clinic. The purpose of this study was to evaluate the feasibility of using carbon nanoparticles to track lymph nodes metastases in T1-2 colorectal cancers.

METHODS: A multi-center study was performed between July 2012 and January 2014. Seventy-three patients with T1-2 colorectal cancer identified by pre-op endoscopic ultrasonography (EUS) were recruited. 1 ml carbon nanoparticles suspension was endoscopically injected into the submucosal layer at four points around the site of the primary tumor 1 day before surgery. Laparoscopic radical resection with lymphadenectomy was performed. Sentinel lymph nodes (SLNs) were defined as nodes that were black-dyed by carbon nanoparticles. Pathology confirmed whether lymph nodes have cancer metastases and the SLNs accuracy.

RESULTS: SLNs were easily found under laparoscopy. The mean number of SLNs was 3 (range 1-5). All patients had SLNs lying alongside the mesenteric vessel or main arterial vessel. After pathological analysis, 2 patients (9.52%) had lymph node metastasis in 21 patients with EUS T1 cancers, and 10 patients (19.23%) had lymph node metastasis in 52 patients with EUS T2 cancers. In two T1 cases with lymph node metastasis, SLNs were positive with 100% accuracy. In ten T2 cases with lymph node metastasis, SLNs were positive in nine cases. In pathology, carbon nanoparticles were seen in lymphatic vessels, and lymphoid sinus and macrophages in negative SLNs. When SLNs were positive, carbon nanoparticles were seen around cancer cells in lymph nodes. The overall sensitivity, specificity, accuracy of SLNs in T1-2 colorectal cancers were 91.67, 100, 98.63%, respectively.

CONCLUSIONS: We demonstrated the feasibility of using carbon nanoparticles to track lymph nodes metastases in T1-2 colorectal cancers. Carbon nanoparticles black-dyed lymph nodes play a role as SLNs in T1-2 colorectal cancers.