1. the indications for surgery in patients with concurrent lung adenocarcinoma should be (1) all solid tumors, (2) mixed GGOs, (3) larger pure GGOs, (4) small but located in an easily operable site, (5) tumor growth, and (6) increased solid component; 2. preoperative diagnosis and determination of the priority and extent of surgical resection by imaging presentation of the tumor is very useful; 3. The difference in features or the presence of GGO suggests SPLC; 4. The priority level of resection should be judged according to the performance of the tumor lesion, such as the side of solid tumor should be resected first; 5. The main tumor lesion + the ipsilateral GGO that is convenient to resect, and other pure GGO should be monitored; 6. Treatment decisions should be made according to the actual lung function of the patient; 7. There is no clear guideline, so clinicians physicians need multidisciplinary discussion to decide the treatment plan. Original Overview: Surgical resection is the mainstay of treatment for multiple primary lung cancers. In recent years, the prevalence of concurrent primary lung adenocarcinoma (SPLA) has gradually increased, yet few studies have evaluated the outcome of surgery in patients. In view of this, Professor Yoshihiro Ishikawa et al. from Japan reviewed the clinicopathological characteristics and surgical outcomes of patients with SPLA to identify survival-related factors, and the article was published in a recent issue of the ATS journal. The study collected and retrospectively analyzed data from 2041 consecutive patients with primary non-small cell carcinoma who underwent surgical resection at the institution from 1995 to 2009. The study found 93 patients with pathologically confirmed SPLA, 26 of whom had bilateral tumors. 5-year overall survival and recurrence-free survival rates were 87.0% and 81.8%, respectively. There was no 30-day operative mortality. Univariate analysis showed that lymph node metastasis, predominant histological type of adnexal growth and the largest diameter of the tumor on computed tomography were significantly associated with overall survival. Multivariate analysis showed that bilateral distribution of tumor, lymph node metastasis and sublobar resection were independent predictors of poor prognosis. This study suggests that surgery in patients with SPLA has good outcomes and should be aggressively pursued. Lymph node status plays an important role in evaluating the availability of surgical pointers. Bilateral tumors predict a poor prognosis for patients and require caution. Lung lobectomy has a high cure rate and should be used whenever possible. However, sublobar resection should be considered in patients with expected poor postoperative lung function. Alessandro Baisi : We carefully read the paper by Ishikawa and his colleagues. In our actual clinical work the presence of other suspicious pulmonary nodules outside the main lesion of resectable lung cancer under computed tomography is very common. The authors’ findings confirmed that the 3- and 5-year survival rates for patients with surgically resected early synchronous primary lung adenocarcinoma were 93.6% and 87%, respectively. Notably they found that patients with nodules distributed in bilateral lung fields and with non-adherent growth of the largest tumors had a poorer prognosis. The study also found that patients with solid tumors who underwent lobectomy had a better prognosis, and sublobar resection was recommended for ground glass shadowing (GGO). We congratulate the investigators whose findings will provide us with a basis to guide treatment decisions for patients with lung cancer with multiple clinical nodes. However, we are primarily concerned with the criteria for inclusion of patients in this study. The authors included both solid and non-solid patients with concurrent multiple primary adenocarcinomas in the same population. recent studies by Gu and colleagues have shown that solid, non-adherent growth type GGO and squamous adenocarcinoma have different oncologic behavior: the first subtype is focal and invasive, whereas the second subtype has inert tumor characteristics. In addition, squamous adenocarcinoma is a multifocal tumor. Therefore, patients with two or more ipsilateral or bilateral GGOs should not be considered as different tumors of simultaneous nature, but as a single multifocal disease. Based on this fact, the surgical strategy should be altered according to the histological type. In case of concurrent tumors, all nodes should be resected to achieve a radical result. However, with multifocal inert tumors, Gu and colleagues recommend resection of the main tumor + the GGO that is easily resectable, with other pure GGOs being monitored. In our opinion, the real problem lies in the preoperative diagnosis of concurrent lung cancer. The fact that nodules are often small or centrally located in the lung parenchyma makes non-surgical biopsy difficult or impossible to perform. In addition, cytology and examination often do not correctly specify the histological type of the tumor, especially GGO. this leads to great difficulty in differentiating simultaneous metastatic disease, there are no specific guidelines, and clinicians often have difficulty determining the best treatment strategy. We believe that the authors’ results encourage patients with N0 unilateral multiple nodules to undergo surgical treatment, but further data are needed to better define the issues of (1) how to properly treat bilateral pulmonary nodules, (2) which side of the cut to resect first and (3) the extent of resection. Response: We thank Baisi and colleagues for their comments on our study. They point out that multifocal lung cancers (MFLCs) were included in our study because the aim of our study was to obtain a comprehensive picture of the overall prognosis of surgically treated simultaneous multiple lung adenocarcinomas, so a broader patient population was included. In this group of patients with multiple lung nodules, the decision of which lesion to resect and which to preserve should be judged by imaging presentation and clinical features and decided through multidisciplinary discussion. Even with ground glass shadows (GGOs), which can be MFLCs, GGOs should be surgically resected when they are large, increasing in size, or have a realistic component. Because we had 5 patients (5.4%) with pure GGOs-dominant tumors presenting in this way were also included in the study. We agree with the study by Gu and colleagues on the surgical treatment of multifocal adenocarcinoma. However, we believe that their study also did not distinguish between MFLCs and synchronous primary lung cancers (SPLCs). Although the radiological features of the primary lesion were not described, the majority of patients (71.8%) exhibited major histological features of squamous growth (including adenocarcinoma with fine bronchoalveolar features). The modified study population was similar to our study, in which the majority of patients (67.7%) had a primary lesion of squamous predominant adenocarcinoma (including squamous predominant invasive carcinoma). We believe that the indication for surgery should be all solid tumors as well as patients with mixed GGOs, larger pure GGOs, small but located at an easily operable site or tumor growth; this treatment strategy is similar to that of Gu and colleagues. Preoperative diagnosis and surgical treatment of bilateral SPLC is very difficult. We believe that preoperative diagnosis and prioritization and extent of surgical resection by imaging presentation of the tumor is very useful. Differences in imaging features of the tumor or the presence of GGO suggest SPLC. As for the priority level of resection, it should be judged by the presentation of the tumor lesion, such that the side with solid tumor should be resected first. In our study, the higher use of sublobar resection in patients with bilateral pulmonary nodules may be the main reason for the poorer prognosis of patients with bilateral lesions. Therefore, lobectomy should be performed for solid tumors, and lung segmental resection is a treatment option for solid tumors of small peripheral size, but treatment decisions should be made based on the actual lung function of the patient.