Background: A lateral pelvic lymph node dissection (LPLD) for lower rectal cancer may be beneficial for a limited number of patients. If sentinel node (SN) navigation surgery could be applied to lower rectal cancer, then unnecessary LPLDs could be avoided. The aim of this study was to investigate the feasibility of lateral region SN biopsy by means of indocyanine green (ICG) visualized with a near-infrared camera system (Photodynamic Eye, PDE).
Methods: This study investigated the existence of a lateral region SN in 25 patients with lower rectal cancer. ICG was injected around the tumor, and the lateral pelvic region was observed with PDE.
Results: With PDE, the lymph nodes and lymph vessels that received ICG appeared as shining fluorescent spots and streams in the fluorescence image. This allowed the detection of not only tumor-negative SNs but also tumor-positive SNs as shining spots. The lateral SNs were detected in 6 of 6 T1 and T2 diseases and 17 of 19 T3 diseases. The lateral SNs were successfully identified in 23 (92%) of the 25 patients. The mean number of lateral SNs per patients was 2.1. Of the 23 patients, 6 patients underwent LPLD. Of the 3 patients who had a tumor-negative SN, all dissected lateral non-SNs were negative in all 3 cases.
Conclusions: We could detect the lateral SNs, not only in T1 and T2 disease, but also in T3 disease. Although this is only a preliminary study, the detection of lateral SNs in lower rectal cancer by means of the ICG fluorescence imaging system is considered to be a promising technique that may be used for determining the indications for performing LPLD.