In 1995, GinsbergRJ and RubinsteinLV published a study in AnnThoracSurg about lobectomy versus limited pneumonectomy for T1N0 early-stage non-small cell lung cancer. randomized clinical study, which showed that limited pneumonectomy did not improve perioperative morbidity, mortality, or postoperative lung function compared with lobectomy. Limited pneumonectomy has a higher mortality and local recurrence rate compared to lobectomy. Therefore, lobectomy is considered the surgical procedure of choice for patients with peripheral T1N0 early-stage non-small cell lung cancer. With changes in imaging modalities and the increased frequency of CT screening, including increased screening for small-sized or ground glass-like lung tumors, pulmonary sublobar resection has gained widespread interest due to less impairment of lung function and better tolerability. In 2009, a multicenter, randomized, controlled, non-inferiority phase III study of lobectomy or lung segmental resection for stage IA NSCLC (tumor diameter ≤2 cm; solid tumor ratio >0.5) was conducted by Prof. Asamura as the lead PI (JCOG0802). The study results were officially published in the Lancet Main Journal on April 22, 2022, changing the landscape of early-stage lung cancer treatment. The study was conducted at 70 institutions in Japan. Patients with a clinical diagnosis of stage IA NSCLC (tumor diameter ≤2 cm; solid tumor ratio >0.5 (the study also enrolled 136 cases with CTR ≤0.5 due to modified CTR enrollment criteria during the study)) were randomly assigned 1:1 to undergo lobectomy or segmental lung resection. The primary endpoint was the overall survival of all randomly assigned patients. Secondary endpoints were postoperative respiratory function (6 and 12 months), recurrence-free survival, proportion of local recurrences, adverse events, proportion of lung segment resections completed, length of hospital stay, chest tube placement time, operative time, operative volume blood loss, and number of automated surgical sutures used. Between August 10, 2009, and October 21, 2014, 1106 patients (intention-to-treat population) were enrolled to undergo lobectomy (n=554) or lung segmental resection (n=552). Patient baseline clinicopathological factors were well balanced between the groups. In the segmental lung resection group, 22 patients were converted to lobectomy and 1 patient underwent a wide wedge resection. The 5-year overall survival rate was 94.3% (92.1-96.0) for lung segment resection and 91.1% (95% CI 88.4-93.2) for lobectomy (HR 0.663, 95% CI 0.474-0.927, non-inferiority test p<0.0001, superiority test p=0.0082); in all predefined subgroups of the lung segment resection group improvement in overall survival was consistently observed in all predefined subgroups of the lung segment resection group. The 5-year recurrence-free survival rate was 88.0% (95% CI 85.0-90.4) for lung segment resection and 87.9% (84.8-90.3) for lobectomy (HR 0.998, 95% CI 0.753-1.323; p=0.9889). In terms of lung function protection, although FEV1 did decline less in the lung segment resection group (6 months postoperatively: 10.4% vs. 13.1%,p<0.0001; 1 year postoperatively: 8.5% vs. 12.0%,p<0.0001), with differences of 2.7% (6 months postoperatively) and 3.5% (1 year postoperatively), respectively, the set 10% postoperative 1-year clinically meaningful difference was not reached difference. The proportion of patients with local recurrence was 10.5% for segmental lung resection and 5.4% for lobectomy (p=0.0018). 52 of 83 patients (63%) died of other diseases after lobectomy and 27 of 58 patients (47%) after segmental lung resection. No 30-day or 90-day mortality was observed. The incidence of one or more grade 2 or more severe postoperative complications was similar in both groups (142 [26%] patients underwent lobectomy and 148 [27%] patients underwent segmental lung resection). An analysis of the causes of death of patients shows that more patients in the lobectomy group died from other diseases, a difference that stems mainly from other cancer-related (including second primary lung cancer). However, we can see that the percentage of patients presenting with secondary cancers is similar in both groups (15.9% vs. 15.2%). The number of incidences of second primary lung cancer was 36 and 43, respectively, and the number of other cancers was 70 and 69, respectively. Among patients with postoperative recurrence, 18/37 of the lobectomized patients survived after 5 years of follow-up, while 35/51 of the lung segment group survived at the same time point. Eighty percent (35/44) of patients with lobectomy received complete treatment compared to 93% (62/67) in the segmental lung resection group, including 13 reoperations, 13 radiotherapy, 32 chemotherapy, and 4 radiotherapy cases. For second primary lung cancer, 89% (32/43) of the segmental lung resection group underwent surgical resection compared to 63% (19/30) of the lobectomy group. The JCOG0802 study was the first phase III trial to show an overall survival benefit of lung segmental resection versus lobectomy in patients with peripheral small NSCLC. The results showed that segmental lung resection was significantly better than lobectomy in terms of overall survival (more people died of other diseases in the lobectomy group); for the first time, it demonstrated that although segmental lung resection had an increased rate of local recurrence, more lung parenchyma preservation improved the space to tolerate disease progression, second primary cancer, and other subsequent treatments; thus establishing segmental lung resection as the standard procedure for ≤2 cm diameter, CTR >0.5 solid-dominant peripheral lung cancer. This has established the status of segmental lung resection as the standard procedure for peripheral lung cancer with solid CTR>0.5. The JCOG0802 study found that the local recurrence rate was significantly higher in the segmental lung resection group than in the lobectomy group by a factor of 2, which was attributed to the smaller extent of resection in the segmental lung resection group. Postoperative follow-up suggested that more patients with lung segments received additional intensive treatment, including resection of recurrent lesions, radiation therapy, or a second primary cancer. The reason may be that segmental lung resection that preserves more lung parenchyma not only provides more room for treatment of recurrent lesions and second primary lung cancer, but also helps with further treatment of other cancers or fatal disease. The JCOG0802 study will also have a profound impact on the way lung cancer is surgically treated in the future. Surgery for lung cancer requires not only radical treatment, but also more preservation of lung tissue for subsequent radical treatment of recurrent/metastatic or second primary lung cancer again. With the development of medical technology, minimally invasive surgery has replaced traditional open-heart surgical treatment as the standard surgical procedure for lung nodule removal. As to which surgical procedure to choose, a detailed evaluation is needed before surgery, mainly based on the location, size and number of nodules, pathological type, patient’s cardiopulmonary function and ability to tolerate surgery.