Society: SSAT

BACKGROUND: Despite the advances in the multidisciplinary treatment of gastric adenocarcinoma, the overall 5-year survival remains only 33.3% in North America. R0 resection with adequate lymphadenectomy remains the mainstay therapy. The National Comprehensive Cancer Network (NCCN) guidelines recommend harvesting 16 or more lymph nodes for adequate staging. This study examines the rate of adequate lymphadenectomy over recent years and its potential association with overall survival.

METHOD: The National Cancer Database (NCDB) was utilized to identify patients who underwent surgical treatment for gastric adenocarcinoma between 2006-2019. Trend analysis was performed for lymphadenectomy rates during the study period. Logistic regression and the Kaplan-Meier survival methods were utilized.

RESULTS: A total of 57,039 patients who underwent surgical treatment for gastric adenocarcinoma were identified. Most patients were male (65.9%), Caucasian (73.8%), with a mean age of 67 years old (SD±11.3). Subtotal gastrectomy was the most common surgery type (48%), followed by total gastrectomy (42.4%). A total of 64.2% of patients underwent surgery in low-volume facilities (1-10 gastrectomies/year). Most patients were American Joint Commission on Cancer (AJCC) stage III (37.6%) and were treated in Academic Research Programs (44.6%). Only 50.6% of the patients had retrieval of ≥16 nodes. Trend analysis showed that this rate significantly improved over the years, from 35.1% in 2006 to 63.3% in 2019 (Cochran-Armitage test: p<.0001). The independent predictors of adequate lymphadenectomy included surgery between 2015-2019 (OR: 1.68; 95%CI: 1.57-1.70), surgery in a high-volume facility with ≥ 31 gastrectomies/year (OR:1.68; 95%CI:1.54-1.84), AJCC stage III (OR: 1.55; 95%CI:1.48-1.62), and preoperative chemotherapy (OR:1.53; 95%CI:1.46-1.61). Compared to patients who received adequate lymphadenectomy, patients who underwent gastrectomy with the removal of < 16 lymph nodes had a worse overall survival: 43 months versus 59 months (Log-Rank: p<.0001). Adequate lymphadenectomy was independently associated with improved overall survival (HR:0.80; 95%CI:0.78-0.82). Other factors associated with improved survival included Asian race (HR:0.72; 95%CI:0.68-0.76), surgery in an Academic facility (HR: 0.91; 95%CI:0.88-0.95), high-volume facility (HR:0.87; 95%CI:0.81-0.90), surgery between 2015-2019 (HR:0.87; 95%CI:0.84-0.90), and receipt of perioperative chemotherapy (HR: 0.62;95%CI:0.59-0.66).

CONCLUSIONS: Although there was a significant improvement in the rate of adequate lymphadenectomy over the study period, as of 2019, 36.7% of patients lacked removal of 16 lymph nodes or more, which was independently associated with poorer overall survival. These findings identify areas for improving the quality of surgical treatment of gastric cancer in North America is warranted.

Figure 1. Mosaic plots showing the increased rate of adequate lymphadenectomy over the years. <br /> Footnote:<b> A:</b> Lymphadenectomy < 16 nodes; <b>B:</b> Lymphadenectomy ≥ 16 nodes. Cochran-Armitage trend test: P <.0001.

Figure 1. Mosaic plots showing the increased rate of adequate lymphadenectomy over the years.
Footnote: A: Lymphadenectomy < 16 nodes; B: Lymphadenectomy ≥ 16 nodes. Cochran-Armitage trend test: P <.0001.

Kaplan-Meier plot comparing the overall survival between patients who underwent gastrectomy for adenocarcinoma with and without adequate lymphadenectomy.<br /> Footnote:<b> Group 1:</b> Lymphadenectomy < 16 nodes; <b>Group 2: </b>Lymphadenectomy ≥ 16 nodes.

Kaplan-Meier plot comparing the overall survival between patients who underwent gastrectomy for adenocarcinoma with and without adequate lymphadenectomy.
Footnote: Group 1: Lymphadenectomy < 16 nodes; Group 2: Lymphadenectomy ≥ 16 nodes.

Felipe Maegawa

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