Inadequate lymph node staging common in gastric adenocarcinoma

The majority of patients who underwent curative-intent gastrectomy for stage I to III gastric adenocarcinoma received inadequate lymph node staging, according to study results.

Patients who received inadequate lymph node staging also demonstrated significantly shorter OS, regardless of other clinical variables, researchers added.

Guidelines issued by the American Joint Commission on Cancer and the National Comprehensive Cancer Network recommend examination of at least 15 lymph nodes for adequate staging of resectable gastric adenocarcinoma. However, the guidelines were established prior to mainstream use of multimodality therapy, and the effect of inadequate lymph node staging has not been studied comprehensively in a contemporary cohort, according to background information in the study.

Jashodeep Datta, MD, of the department of surgery at the University of Pennsylvania’s Perelman School of Medicine, and colleagues assessed the frequency with which patients received adequate lymph node staging, the factors that predicted inadequate staging, and the relationship between staging and OS.

Datta and colleagues used the National Cancer Data Base to identify 22,409 patients with stage I to stage III gastric adenocarcinoma who underwent gastrectomy between 1998 and 2011.

The median age of patients was 68 years (range, 58-76). The majority of patients were white (75.2%) and male (61.8%). The majority of tumors evaluated were >2 cm (76.8%) and had either poorly differentiated or undifferentiated histology (60.7%).

Results showed compliance with guidelines was poor, as a median 61.2% of patients underwent inadequate lymph node staging during the study period.

The percentage of patients who underwent inadequate lymph node staging increased from 23.7% per year in 1998 to 42.3% per year in 2011 (P<.0001), indicating that 57.7% of patients underwent inadequate lymph node staging as recently as 2011. The adequacy compliance rate peaked at 47.8% in 2009.

The median number of lymph nodes examined per patient increased from eight (interquartile range, 2-14) in 1998 to 12 (interquartile range, 3-20) in 2011 (P<.0001). The number peaked at 14 (interquartile range, 7-22) in 2009.

The strongest predictor of inadequate staging was receipt of subtotal or partial gastrectomy (OR=2.01; 95% CI, 1.78-2.26). Patients treated at community cancer centers were more likely than those treated at academic/research institutions to undergo inadequate staging (OR=1.92; 95% CI, 1.66-2.22).

The researchers included 9,139 patients in the survival analysis.

Among the entire cohort, median OS was 35.6 months. Researchers reported a 1-year OS rate of 75.5% and a 5-year OS rate of 39.7%. Lymph node positivity (HR=1.9; 95% CI, 1.75-2.06), age ≥76 years (HR=1.73; 95% CI, 1.53-1.97) and R1 resection (HR=1.67; 95% CI, 1.49-1.87) were the strongest predictors of shorter OS.

Researchers determined patients who received inadequate lymph node staging experienced significantly shorter median OS than those who received adequate staging (33.3 months vs. 42 months; HR=1.33; 95% CI, 1.24-1.43), regardless of tumor T classification or AJCC clinical stage subgroup (P<.001 for both).

“OS improved incrementally with higher lymph node counts, undoubtedly reflecting the contribution of stage migration,” Datta and colleagues wrote. “A therapeutic benefit of regional lymphadenectomy or influence of other unaccounted for factors are not excluded. Regardless of the underlying mechanism, the survival impact of inadequate lymph node staging, suggests that examination of ≥15 lymph nodes should be considered a benchmark for quality of care because it appears to be a reproducible prognosticator of gastric cancer outcomes in the United States.”

Disclosure: The researchers report no relevant financial disclosures.