AIM: The role of lymph node dissection (LND) in gastric adenocarcinoma (GAC) remained some controversy. This study reappraised the clinical implications of LND for GAC in terms of the numbers of total lymph node (TLN), positive lymph node (PLN) and negative lymph node (NLN). METHODS: A total of 106 GAC patients receiving an upfront gastrectomy (laparoscopic/laparotomy surgery, 19/87) with LND (D1/D1+/D2 dissection, 5/53/48) between Jan 2017 and Dec 2021 in Cathay General Hospital, Taipei were analyzed. The surgical-pathological T-/N-/M-status and cancer stage were determined according to the American Joint Committee on Cancer (AJCC) 8th edition. The numbers of TLN, PLN and NLN were recorded for analysis (TLN = PLN + NLN). The associations between prognosis and related variables, including pathological findings, the clinical implications of TLN/PLN/NLN and extent for LND, were all deeply studied. RESULTS: Advanced T-status (p <
0.001), N-status (p = 0.025), M-status (p = 0.001) and cancer stage (p = 0.001) had a negative effect on survival. The severity of N-status was associated with the progression of T-status (p <
0.001), M-status (p = 0.015) and cancer stage (p <
0.001). For all 106 GAC patients (p = 0.002/0.017) and the 25 T1 GAC patients (p = 0.052/0.015), those undergoing TLN >
17 (≥18) had a more PLN and a higher rate of N(+) than those ≤17. For 65 N(+) GAC patients, an extension of TLN to ≥23 allowed the detection of a median value for PLN of 7, the N3-status. NLN >
9 (≥10) was related to a better prognosis (p = 0.066) and lower HR (p = 0.073) for N(+) GAC patients. TLN with threshold value ≥20 owned the best power to distinguish NLN >
9 (≥10) from ≤9 among N(+) GAC patients (p <
0.001). A D2 dissection could achieve these thresholds, including TLN ≥18 (p = 0.001) for GAC patients, TLN ≥23 (p = 0.028) for N(+) GAC patients, and NLN ≥10 (p = 0.012) as well as TLN ≥20 (p = 0.011) for N(+) GAC patients, more effectively than a D1/D1+ dissection. CONCLUSIONS: A value of TLN ≥18 is necessary for de-novo GAC patients during gastrectomy to detect possible N(+) status, and ≥23 is recommended for N(+) GAC patients to identify the possible N3-status. A value of NLN ≥10 could reach a better survival for N(+) GAC patients and it requires a value of TLN ≥20 to achieve. A D2 dissection is recommended for GAC patients during gastrectomy. LND establishes adequate N-status staging and increases survival for GAC patients.