The pattern of lymph node metastasis in patients with peripheral non-small cell lung cancer >2-3 cm.

Background: Several studies have reported the pattern of lymph node (LN) metastasis in patients undergoing segmentectomy for non-small cell lung cancer (NSCLC) <2 cm. However, the pattern of LN metastasis in cases of NSCLC >2-3 cm remains unknown.

Methods: This retrospective study reviewed the clinicopathological features of 406 consecutive patients with NSCLC (≤3 cm, cN0) who underwent segmentectomy or lobectomy between January 2017 and December 2023. The tumours were classified into part-solid tumours ≤2 cm (Group A, n = 80), pure-solid tumours ≤2 cm (Group B, n = 72), part-solid tumours >2-3 cm (Group C, n = 140), and pure-solid tumours >2-3 cm (Group D, n = 113). Patterns of LN metastasis, recurrence, and pathological invasive factors were compared amongst the four groups.

Results: The number of patients with pN1/pN2a/pN2b in Groups A, B, C, and D were 0/1/0, 4/0/0, 5/6/1, and 9/2/3, respectively. There was no difference in the pathological invasive factors between Groups A and B. No patient with part-solid tumours had non-adjacent interlobar LN metastasis or hilar or mediastinal LN recurrence. Group D (37.2%) had more lymphatic invasion than Group C (25.0%) (P = 0.040). One patient with a pure-solid tumour had non-adjacent interlobar LN metastasis. None of the patients with part-solid tumours in the upper lobe experienced recurrence outside the region of selective LN dissection.

Conclusion: Non-adjacent interlobar or mediastinal lymph node dissection may be omitted for pure-solid tumours even if indicated segmentectomy for NSCLC >2-3 cm. Selective LN dissection is adequate for patients with pure-solid upper lobe tumours >2-3 cm.