Sentinel Lymph Node Biopsy in Colon Cancer: an Institutional Experience

Abstract

Lymph node staging is a major prognostic factor in colorectal cancer and remains to be the most important criterion for selecting patients for adjuvant therapy. The standard approach for lymph node evaluation is based on manual dissection and histological evaluation of HE-stained slides. For stage III disease (node positive), adjuvant chemotherapy increases the survival rate, while in node-negative stage II disease, in most cases, the chemotherapy is contraindicated due to increased morbidity without real benefit. Up to 30% of patients with node-negative colon cancer staged by standard pathologic techniques ultimately suffer disease recurrence and tumour-related mortality following potentially curative primary resection. Variations in outcome among patients with node-negative early-stage disease may reflect inadequate nodal resection and inaccuracies of pathologic staging. Hence, an accurate pN stage becomes essential. It is seen that classic pathological exam sometimes fails to identify lymph node micrometastases or isolated tumour cells, which might explain local or distant relapses in stage II patients. Sentinel lymph node study has the potential to detect micrometastases and lead to upstaging the disease which is crucial for planning adjuvant therapy and follow-up in these patients. In our study, we carried out SLNB in 40 clinically stage II patients operated for colon cancer. We used peritumoural injection of dye at the time of surgery to detect SLN(s) and analysed them using both microsectioning and immunohistochemical (IHC) staining. Our results show that SLNB can improve the accuracy of pTNM staging.