The impact of the number of lymph node metastases on the overall recurrence of colon cancer in the era of sentinel lymph node mapping

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Background: Sentinel Lymph Node Mapping (SLNM) in colon Cancerc (Cca) has been shown to be successful, sensitive and accurate. We aimed to evaluate the recurrence rates in patients(pts) with Cca after SLNM and correlate it to the number of positive(+ve) LNs. Methods: Between 1996 and 2006, pts diagnosed with Cca were enrolled in a prospective trial and underwent SLNM and oncologic resection including regional LNs. The primary outcome was development of recurrence with minimum follow-up (f/u) of 24 months. For recurrence analysis, exclusion criteria included: stage IV disease, benign pathology, lost to follow-up, refusal of indicated chemotherapy, non cancer related death or second cancer. A retrospective matched control (diagnosed with Cca undergoing standard colon resection without SLNM, gp B) from our own institution were analyzed and compared to the SLNM group for the same period. Results: A total of 486 pts with Cca were included. Of these, 272 consecutive pts underwent SLNM between 1996–2006. SLNM was successful in 99.8% of pts, with a sensitivity, negative (-ve) predictive value, and overall accuracy of 85.3%, 91.7% and 94.4% respectively. The nodal positivity was 46.0%; of these, 15.1% had micrometastasis. The average number of LNs resected / pt was 15.0 and the average number of SLNs / pt was 2.4. For recurrence analysis, 153/272 pts with minimum f/u 2 years were included. Of these, 49 had stage I, 46 had stage II and 58 had stage III disease. The recurrence rates were 4.1%, 8.6% and 15.5% in stage I, II, and III disease respectively. The recurrence rates were significantly lower when our 153 pts were compared to 214 matched controls ( table 1 ). The recurrence rates increased from 6.3% in pts with no +ve LNs to 11.5% when one LN was +ve, 16.7% when 2 LNs were +ve and 20% when 3 or more LNs were +ve. Conclusions: SLNM in Cca is associated with decreased rates of recurrence as compared to conventional therapy. The number of positive LNs is an independent risk factor for recurrence.

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No significant financial relationships to disclose.