Segmentectomy versus lobectomy in small-sized peripheral non-small-cell lung cancer with radiologically pure-solid appearance in Japan (JCOG0802/WJOG4607L): a post-hoc supplemental analysis of a multicentre, open-label, phase 3 trial

Although segmentectomy was better than lobectomy in terms of overall survival for patients with non-small-cell lung cancer (NSCLC) with a pure-solid tumour appearance on thin-section CT in the open-label, multicentre, randomised, controlled, phase 3 JCOG0802/WJOG4607L trial, the reasons why segmentectomy was associated with better overall survival were unclear. We aimed to compare the survival, cause of death, and recurrence patterns after segmentectomy versus lobectomy in trial participants with NSCLC with a pure-solid appearance METHODS: We conducted a post-hoc supplemental analysis of the JCO0802/WJOG4607L randomised, controlled, non-inferiority trial for the patients (aged 20-85 years) with small-sized NSCLC with radiologically pure-solid appearance on thin-section CT (≤2 cm, consolidation tumour ratio 1·0). The primary aim was to compare the overall and relapse-free survival, cause of death, and recurrence patterns associated with segmentectomy and lobectomy for patients with radiologically pure-solid NSCLC to determine why the overall survival of segmentectomy was superior to that of lobectomy, even for oncologically invasive lung cancers. JCO0802/WJOG4607L is registered with the UMIN Clinical Trials Registry, UMIN000002317, and is complete.Between Aug 10, 2009, and Oct 21, 2014, 1106 patients were randomly assigned to undergo either lobectomy or segmentectomy. Of these participants, 553 (50%) had radiologically pure-solid NSCLC and were eligible for this post-hoc supplemental analysis. Of these 553 participants, 274 (50%) patients underwent lobectomy and 279 (50%) underwent segmentectomy. Median patient age was 67 years (IQR 61-73), 347 (63%) of 553 patients were male and 206 (37%) were female, and data on race and ethnicity were not collected. As of data cutoff (June 13, 2020), after a median follow-up of 7·3 years (IQR 6·0-8·5), the 5-year overall survival rate was significantly higher after segmentectomy than after lobectomy (86·1% [95% CI 81·4-89·7] in the lobectomy group, with 55 deaths vs 92·4% [88·6-95·0] in the segmentectomy group, with 38 deaths; hazard ratio (HR) 0·64 [95% CI 0·41-0·97]; log-rank test p=0·033), whereas the 5-year relapse-free survival was similar between the groups (81·7% [95% CI 76·5-85·8], with 34 events vs 82·0% [76·9-86·0], with 52 events; HR 1·01 [95% CI 0·72-1·42]; p=0·94). Deaths after a median follow-up of 7·3 years due to lung cancer occurred in 20 (7%) of 274 patients after lobectomy and 19 (7%) of 279 after segmentectomy, and deaths due to other causes occurred in 35 (13%) patients after lobectomy compared with 19 (7%) after segmentectomy (lung cancer death vs other cause of death, p=0·19). The locoregional recurrence was higher after segmentectomy (21 [8%] vs 45 [16%]; p=0·0021). In subgroup analyses, better 5-year overall survival after segmentectomy than after lobectomy was observed in the subgroup of patients aged 70 years or older (77·1% [95% CI 68·2-83·8] with lobectomy vs 85·6% [77·5-90·9] with segmentectomy; p=0·013) and in male patients (80·5% [73·7-85·7] vs 92·1% [87·0-95·2]; p=0·0085). By contrast, better 5-year relapse-free survival after lobectomy than after segmentectomy was observed in the subgroup younger than 70 years (87·4% [95% CI 81·2-91·7] with lobectomy vs 84·4% [77·9-89·1] with segmentectomy; p=0·049) and in female patients (94·2% [87·6-97·4] vs 82·2% [73·2-88·4]; p=0·047).This post-hoc analysis showed improved overall survival after segmentectomy in patients with pure-solid NSCLC compared with lobectomy. However, survival outcomes of segmentectomy depend on the patient's age and sex. Given the results of this exploratory analysis, further research is necessary to determine clinically relevant indications for segmentectomy in radiologically pure-solid NSCLC.Japanese National Cancer Center Research and Development Fund and Practical Research for Innovative Cancer Control Fund, and a Grant-in-Aid for Scientific Research from the Ministry of Health, Labor, and Welfare of Japan.