Tumour location predicts occult N1 nodal metastasis in clinical stage I non-small-cell lung cancer

Abstract

Objectives Pathological lymph node metastases are often observed in patients with clinical N0 lung cancer. Identifying preoperative predictors of occult hilar nodal metastasis is important in determining the surgical procedure in patients with clinical stage I non-small cell lung cancer. This study aimed to determine the frequency and predictors of occult hilar nodal metastasis by tumour location in these patients. Methods Between April 2007 and May 2019, data of patients who underwent lobectomy or segmentectomy for clinical stage I pure-solid non-small cell lung cancer were retrospectively reviewed. The ratio of the distance from the pulmonary hilum to the proximal side of the tumour to the distance from the pulmonary hilum to the visceral pleural surface through the centre of the tumour, named “distance ratio,” was calculated. The relationship of the distance ratio with clinicopathological findings and prognosis was discussed. Results A total of 357 patients were enrolled. Occult hilar nodal metastasis frequency was 14.6%. Patients were divided into two groups based on whether the distance ratio was ≤0.67 (central-type) or > 0.67 (peripheral-type). The frequency of occult hilar nodal metastasis was significantly higher in the distance ratio ≤0.67 group (21.5% vs 7.4%; P < 0.001). Multivariable analysis revealed that distance ratio was the only independent preoperative predictor of occult hilar nodal metastasis (odds ratio, 3.63; 95% confidence interval, 1.83–7.18; P < 0.001). Conclusions The frequency of occult hilar nodal metastasis was significantly higher in peripheral-type lung cancer; therefore, tumour location was the most important preoperative predictor of occult hilar nodal metastasis.

Lymph node metastasis and its risk factors in T1 lung adenocarcinoma

“…19 In 2022, we published a study in the Journal of Translational Lung Cancer Research on the factors influencing the measurement accuracy of this method in each lung lobe and pointed out that the depth ratio method could accurately distinguish the inner, middle, and outer band ranges in three-dimensional space and eliminate the interference of mediastinal structures, to the greatest extent, in the three symmetrical partitions of the bilateral lungs. 20 The present study found a significant correlation between the probability of lymph node metastasis and the tumor's location within the inner (depth ratio >66.7%) zones, which aligns with the findings of Kawamoto et al 9 Conversely, Tane et al 21 did not observe a significant difference in the rate of lymph node metastasis between internal and external lesions. Additionally, DuComb et al 22 analyzed the NLST database to investigate the relationship between the coordinate position of solid nodules measuring 8-30 mm and N2/N3 lymph node metastasis.…”

“…This study identified depth ratio as an independent risk factor for the development of lymph node metastasis in T1 lung adenocarcinoma. Studies have reported a correlation between the location of the tumor center and lymph node metastasis; the closer the tumor is to the center, the higher the risk of lymph node metastasis 9,17 . Our study yielded similar results.…”

“…Studies have reported a correlation between the location of the tumor center and lymph node metastasis; the closer the tumor is to the center, the higher the risk of lymph node metastasis. 9,17 Our study yielded similar results. At present, there is no consensus on the definition of the central location, and there are few reports on the quantitative criteria for judging the location of a tumor in a threedimensional space.…”

“…At present, there is no consensus on the definition of the central location, and there are few reports on the quantitative criteria for judging the location of a tumor in a three‐dimensional space 9 . The “distance ratio” used by Okada et al, the location index‐position index method used by Choi et al, 18 and the “depth ratio” concept used in our study are variations of the same method.…”

“…Further, Okada et al recently found that the incidence of occult N1 lymph node metastasis in peripheral lung cancer was significantly higher when using the “distance ratio” to determine the lesion location. The distance ratio is an independent factor for predicting the risk of N1 lymph node metastasis before surgery 9 . With in‐depth pathological analyses, the relationship between lung adenocarcinoma subtypes and lymph node metastasis has received increasing attention from researchers.…”