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GREATER LYMPH NODE RETRIEVAL IMPROVES SURVIVAL IN NODE-NEGATIVE RESECTED GASTRIC CANCER
Katelin Mirkin*, Christopher S. Hollenbeak, Joyce Wong
Surgery, Penn State, Hershey, PA
Background:
Western guidelines recommend retrieving 15 or more lymph nodes during gastric cancer resection. This study sought to determine if number of examined lymph nodes (eLN), a proxy for lymphadenectomy, impacts survival, even in node-negative disease.
Methods:
The U.S. National Cancer Data Base (2003-2011) was reviewed for patients with resected gastric adenocarcinoma. Patients with positive lymph nodes or stage IV disease were excluded. Patients were categorized by receipt of neoadjuvant therapy (NAT) versus initial resection, and further stratified by eLN: ≤10, 11-15, 16-20, 21-30 and >30. Univariate and multivariate survival analyses were performed.
Results:
4,126 patients with clinical stages I-III resected gastric adenocarcinoma were included. Of the 1,036 (25.1%) stage II-III patients who received NAT, 40.5% (N=420) had ≤10 eLN, 21.8% (N=226) had 11-15, 16.8% (N=174) had 16-20, 13.4% (N=139) had 21-30, and 7.4% (N=77) >30 eLN. 2,795 stage I-III patients underwent initial surgery; 42.5% (N=1,187) had ≤10 eLN, 19.8% (N=553) had 11-15, 14.5% (N=404) had 16-20, 15.5% (N=432) had 21-30, and 7.8% (N=219) had >30 eLN. In both groups, the majority underwent proximal gastrectomy, followed by total gastrectomy and uncommonly distal gastrectomy. After controlling for patient, cancer, and treatment characteristics, greater eLN was associated with improved survival (NAT cohort: eLN 16-20: HR 0.71, p=0.039, eLN 21-30: HR 0.55, p=0.001; surgery cohort: eLN 11-15: HR 0.81, p=0.021, eLN 16-20: HR 0.73, p=0.004, eLN 21-30: HR 0.62, p<0.001, eLN >30: HR 0.58, p=0.001).
12.8% (N=359) of patients who underwent initial surgery received adjuvant therapy.
Interestingly, adjuvant therapy appears to improve survival in those with a sub-optimal (≤15 eLN) lymphadenectomy in stage II and III disease (5 year survival: 45.2% vs 60.5%, p=0.1538, 49.0% vs 63.0% p=0.5095, respectively).
Conclusion:
In the U.S., the majority of gastric cancer patients have a suboptimal lymphadenectomy. Even in node-negative gastric cancer, greater lymph node retrieval up to 30 eLN appears to have therapeutic and prognostic value, irrespective of initial treatment, suggesting a survival benefit to meticulous lymphadenectomy. Administration of adjuvant therapy appears to attenuate the survival detriment in those who have fewer than 15 eLN.
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