The postoperative prognosis of skip-N2 metastasis is favorable in small-cell lung carcinoma patients with pathological N2 classification: a propensity-score-adjusted retrospective multicenter study

Abstract

Background: The study on skip-N2 metastasis in small-cell lung cancer (SCLC) is lacking. Therefore, this study aimed to explore the prognostic significance of skip-N2 metastasis based on a multicenter cohort. Methods: We collected 176 SCLC patients with pathological categories T1-4N1-2M0 from four hospitals in China. Survival curves were drawn through the Kaplan–Meier method and compared by the log-rank test. The Cox regression method was used to calculate the hazard ratio (HR) and 95% confidence interval of the characteristics for cancer-specific survival (CSS). Two propensity-score methods were used to reduce the bias, including the inverse probability of treatment weighting (IPTW) and propensity-score matching (PSM). Results: This multicenter database included 64 pN1 patients, 63 non-skip-N2 cases, and 49 skip-N2 cases. Skip-N2 and the non-skip-N2 patients had gap CSS rates (skip-N2 no versus yes: 41.0% versus 62.0% for 1-year CSS, 32.0% versus 46.0% for 2-year CSS, and 20.0% versus 32.0% for 3-year CSS). After PSM, there were 32 pairs of patients to compare survival differences between N2 and skip-N2 diseases, and 34 pairs of patients to compare prognostic gaps between N1 and skip-N2 diseases, respectively. The results of IPTW and PSM both suggested that skip-N2 cases had better survival outcomes than the non-skip-N2 cases (IPTW-adjusted HR = 0.578; PSM-adjusted HR = 0.510; all log-rank p < 0.05). Besides, the above two analytic methods showed no difference in prognoses between pN1 and skip-N2 diseases (all log-rank p > 0.05). Conclusions: Skip-N2 patients were confirmed to have a better prognosis than non-skip-N2 patients. Besides, there was no survival difference between pN1 and skip-N2 cases. Therefore, we propose that the next tumor-node-metastasis staging system needs to consider the situation of skip metastasis with lymph nodes in SCLC.

Is there a prognostic difference among stage I lung adenocarcinoma patients with different BRAF‐mutation status?

“…To minimize the bias caused by the different backgrounds of patients, we used propensity‐score matching (PSM) and overlap weighting (OW) in this study 12–14 . OW is regarded as a propensity‐score method that attempts to mimic attributes of randomized clinical trials 15 .…”

“…To minimize the bias caused by the different backgrounds of patients, we used propensity‐score matching (PSM) and overlap weighting (OW) in this study. 12 , 13 , 14 OW is regarded as a propensity‐score method that attempts to mimic attributes of randomized clinical trials. 15 In addition, OW assigns weights to each patient that are proportional to the probability of patients pertaining to the opposite group, thus can be as efficient as randomization if no adjustment is needed.…”

The clinical-histologic and prognostic characteristics in patients with a second primary non-small-cell lung cancer after a lobectomy

“…Given the limited information in the SEER database, we dealt with the missing information by exclusion. The Kaplan-Meier method was used to draw the survival curves, which were compared using the log-rank test [ 9 ]. P -values between subgroups were compared using the Benjamini & Hochberg method.…”