In vivo sentinel lymphatic mapping in rectal cancer

ABSTRACT

Nearly 30% of patients with stage I, II rectal cancer with no evidence of nodal deposits develop systemic disease despite radical curative surgery. It is postulated that a subset group of patients do harbor nodal micrometastases not detected by the classic Hematoxylin and Eosin [H and E] staining. This prospective study aimed to assess the feasibility of in vivo sentinel lymphatic node [SLN] mapping and biopsy in accurate nodal staging and decision making. This might offer a reasonable clue to whether lateral lymph node metastases can be diagnosed by SLN mapping and so provide benefit to patients with advanced rectal cancer regarding consideration of more extensive resection. The study included 25 patients with mid and low rectal tumours. In mid rectal tumours blue dye was injected circumferentially in the peritumoral area in the subserosal plane. Similarly in low rectal tumours submucosal injection around the tumour through proctoscopy was performed. Immediate labeling and prompt dissection of blue stained nodes were followed by the standard radical resection. The sentinel nodes were separately sent for focused histopathological examination, the surgical specimen including other nodes for routine examination. H and E negative SLN were tested Immunohistochemically [IHC]. Sentinel Lymph Node [SLN] mapping was feasible in 24 out of 25 patients [96%] with a mean number of SLN 2.87 patient [0-3].Positive SLN were found in 9 patients [38%] while negative SLN were found in 15 patients [62%].The incidence of metastasis in SLN was 26%.Lateral positive nodes were found in 3 patients [13%].Upstaging of T2-3NO to T2-3N1 was done in 15% of cases. Skip lesions were present in one patient. Sentinel Lymph Node [SLN] In vivo mapping using blue dye is a promising and feasible technique with a short learning curve. Lateral node dissection was excluded in 87% of patients. Proper nodal Staging by SLN focused analysis leads to identification of a subset group of patients that could benefit from Adjuvant therapy