Prognostic Impact of Margin Distance and Tumor Spread Through Air Spaces in Limited Resection for Primary Lung Cancer

Transcription

1 Accepted Manuscript Prognostic Impact of Margin Distance and Tumor Spread Through Air Spaces in Limited Resection for Primary Lung Cancer Kyohei Masai, Hiroyuki Sakurai, Aoi Sukeda, Shigeki Suzuki, Keisuke Asakura, Kazuo Nakagawa, Hisao Asamura, Shun-ichi Watanabe, Noriko Motoi, Nobuyoshi Hiraoka PII: DOI: Reference: JTHO 685 S (17)30727-X /j.jtho To appear in: Journal of Thoracic Oncology Received Date: 6 April 2017 Revised Date: 5 August 2017 Accepted Date: 21 August 2017 Please cite this article as: Masai K, Sakurai H, Sukeda A, Suzuki S, Asakura K, Nakagawa K, Asamura H, Watanabe S-i, Motoi N, Hiraoka N, Prognostic Impact of Margin Distance and Tumor Spread Through Air Spaces in Limited Resection for Primary Lung Cancer, Journal of Thoracic Oncology (2017), doi: /j.jtho This is a PDF file of an unedited manuscript that has been accepted for publication. As a service to our customers we are providing this early version of the manuscript. The manuscript will undergo copyediting, typesetting, and review of the resulting proof before it is published in its final form. Please note that during the production process errors may be discovered which could affect the content, and all legal disclaimers that apply to the journal pertain.

2 Original Article Prognostic Impact of Margin Distance and Tumor Spread Through Air Spaces in Limited Resection for Primary Lung Cancer Kyohei Masai, 1,2,3 Hiroyuki Sakurai, 2,4 Aoi Sukeda, 1 Shigeki Suzuki, 2 Keisuke Asakura, 2 Kazuo Nakagawa, 2 Hisao Asamura 3, Shun-ichi Watanabe, 2 Noriko Motoi 1 and Nobuyoshi Hiraoka 1 1: Division of Pathology, Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Tokyo, Japan 2: Division of Thoracic Surgery, National Cancer Center Hospital, Tokyo, Japan 3: Division of Thoracic Surgery, Keio University School of Medicine, Tokyo, Japan 4: Division of Respiratory Surgery, Nihon University School of Medicine Corresponding author: Noriko Motoi, MD, PhD, Division of Pathology, Department of Pathology and Clinical Laboratories, National Cancer Center Hospital, Tsukiji, Chuo-ku, Tokyo , Japan. TEL; , FAX; address: nmotoi@ncc.go.jp Keywords: Lung cancer, Tumor Spread Through Air Spaces (STAS), Tumor Margin, Limited 1

3 Resection, Local Recurrence. 2

4 ABSTRACT Objectives: To investigate the relationships between clinicopathological prognostic factors, including, surgical margin distance and tumor spread through air spaces (STAS), and recurrence after limited resection for primary lung cancer. Methods: We identified 508 limited resection cases (12.8%) and examined their clinicopathological features. Using Cox regression analysis, we examined the significant prognostic factors for recurrence of limited resection. Finally, we conducted a histopathological evaluation of tumor STAS. Results: Multivariate Cox analysis showed that the risk of local recurrence was significantly associated with STAS (HR 12.24, p = 0.001) and tumor margin < 1.0 cm (HR 6.36, p = 0.02). However, the presence of tumor STAS was not significantly associated with distant recurrence (p = 0.98). This lack of association of STAS with distant recurrence may be due to the small number of distant recurrences. Seventy-six cases (15.0%: 60 adenocarcinomas, 9 squamous cell carcinomas, and 7 others) were positive for STAS. The morphological STAS patterns were 12 single cells, 45 small cell clusters, and 19 large nests. There was no significant relationship between the recurrence rate and morphological STAS pattern. The STAS-positive group was associated with the presence of micropapillary (p = 0.002) and/or solid components (p = 0.008) in adenocarcinoma patients, and with lymphovascular and pleural invasion (p < 0.001). 3

5 Conclusions: The presence of STAS and tumor margins < 1.0 cm are significant risk factors for local recurrence in early-stage lung cancer following limited resection. Thus, the presence of tumor STAS might be a pathologic prognostic factor for patients with lung cancer who have undergone limited resection. However, the pathological and molecular significance of STAS remain to be clarified. 4

6 INTRODUCTION Lobectomy has been the standard surgical procedure for clinical stage IA non-small cell lung cancer (NSCLC) since the 1995 report from the Lung Cancer Study Group (LCSG). 1 However, limited resection, including wedge resection and segmentectomy, is typically considered acceptable for poor-risk patients in order to preserve pulmonary function. 2 Additionally, recent advances in computed tomography (CT) have led to increased detection of small-size lung nodules. 3,4 Therefore, although the evidence is insufficient, the adaptation of intentional limited resection for good-risk patients has recently increased to also include early-stage lung cancer, as well as compromised limited resection for poor-risk patients. 5 For limited resection, the tumor margin distance is the major concern in terms of local control. 6 In previous reports on limited resection, the target tumor margin distance has been reported as > 2.0 cm or as at least the size of the nodule. 7-9 Additionally, many recent reports have shown that certain pathological factors are associated with the survival and recurrence outcomes of these patients. 10,11 Particularly, in primary lung adenocarcinoma, the histologic subtype has been demonstrated to be a determinant of poor prognosis. 12 In the latest World Health Organization (WHO) classification of lung adenocarcinoma, the micropapillary and solid predominant histologic subtypes are reported as significant risk factors of local recurrence and overall survival after limited resection in small-size adenocarcinoma Further, presence of 5

7 tumor spread through air spaces (STAS) was reported as a novel poor prognostic factor in the latest WHO classification. 15 The pathological phenomenon of tumor STAS was first reported as aerogenous spread with floating cancer cell clusters (ASFC) in pulmonary metastases of colorectal carcinoma, and has been shown to be a prognostic factor for colorectal cancer patients who have undergone pulmonary metastasectomy. 16 In pulmonary adenocarcinoma, Kadota et al. first reported a pathological phenomenon similar to ASFC as tumor STAS. In that report, tumor STAS was defined as tumor cells spreading through the air spaces into the lung parenchyma adjacent to the edge of the tumor. Further, tumor STAS was found to be a significant risk factor of disease recurrence in stage I lung adenocarcinoma patients treated with limited resection. Moreover, the authors concluded that tumor STAS is a new invasive factor of primary lung cancer. 17 However, the relationship between the degree of this pathological phenomenon and the postoperative prognosis has not yet been clarified. Further, the pathological implication of STAS is also unknown. Thus, in this present study, we explored the clinicopathological features of primary lung cancer treated with limited resection and examined the significance of the presence of tumor STAS. 6

8 MATERIALS AND METHODS Patient Selection In the 10-year period from January 2004 through December 2013, 3959 patients underwent surgical resection for primary lung carcinoma at the National Cancer Center Hospital, Tokyo. The histological diagnoses were based on the latest WHO classification. 15 Pathologic staging was conducted based on the TNM classification of the American Joint Committee on Cancer Staging Manual (7th edition). 18 Our present study included patients who underwent restricted to limited resections, including segmentectomy or wide wedge resection. We excluded cases with preoperative radiation and/or chemotherapy, positive surgical margins, and unknown distance of the surgical margin from the study population, resulting in a total of 508 patients being included in our analyses. Their clinicopathological features, including their age, sex, smoking history, tumor location, surgical procedure, histology, subtyping for adenocarcinoma, tumor margin distance, pleural involvement, presence of blood vessel or lymphatic vessel invasion, presence of tumor STAS, recurrence pattern, and outcome, were retrospectively reviewed. The postoperative recurrence pattern was divided into three patterns: local, locoregional, and distant recurrences. Local recurrence was defined as any recurrence on the tumor resected line. Locoregional recurrence was defined as any recurrent disease within the ipsilateral hemithorax, lung metastasis, and/or hilar or mediastinal lymph node metastasis. Other distant 7

9 sites of recurrence were considered distant metastases. Recurrence was confirmed by radiologic findings, including CT and/or positron emission tomography. Indications and Surgical Procedure The indication for limited resection was decided based on a combination of the patient s performance status and CT findings. Patients with shadows composed mainly of ground-glass nodules on CT were indicated for intended limited resection. In contrast, we performed compromised limited resection for high-risk patients with any contraindications for standard radical surgery, regardless of the tumor size or presence of a solid component on CT. The surgical technique used was based on the minimally invasive open surgery approach, and aimed at securing sufficient margins of at least 2.0 cm, as determined by palpation. In our institution, the surgeons always perform lung resection by thoracoscopic-assisted minimal incisional thoracotomy, including wedge resection and segmentectomy; hence, they can touch the specimen with their hands directly through the incision to ensure sufficient surgical margins. Tumor Margin Distance The tumor margin distance was measured by pathologists, and the tumor margin distances recorded in the pathological reports were used for the analyses. The tumor margin was defined as the distance from the primary tumor to the closest staple lines. To analyze the association between the surgical margin distance and the recurrence risk, we excluded cases with positive or 8

10 unknown surgical margins from the present study. Histological Diagnosis and Definition of Tumor Spread Through Air Spaces The surgically resected specimens were fixed with formalin, cut serially into 5-mm-thick slices, and macroscopically examined. Additional consecutive 4-µm-thick sections were cut from a selected tissue block and stained with hematoxylin and eosin. All slides were reviewed by two pathologists (KM and NM), who were blinded to the patient outcomes. Histopathological subtyping of primary lung adenocarcinoma was conducted according to the latest WHO classification. 15 In cases of multiple tumor lesions, it is important to judge whether the lesions are second primaries or metastatic tumors. We made this distinction based on a comprehensive morphological assessment following the Martini criteria. For intrapulmonary lesions, the judgement was made not only based on the tumor morphology but also by considering the clinical interval and changes in CT findings during the patient s follow-up. Tumor STAS was defined based on the latest WHO classification as floating tumor cells in the air spaces. 15 As in past reports, floating cells were defined as non-continuous cells less than one alveolus away from the edge of the main tumor. 17,19 Tumor STAS was subdivided into three morphological patterns: single cells, small cell clusters, and large nests (Figure 2). We defined large nest patterns as recognizable tumor nests at a low magnification view. The remaining two 9

11 patterns were classified by the number of tumor cells. The single cell pattern was defined as the presence of only one floating tumor cell in the alveolar space. The small cell pattern was defined as the presence of a few floating tumor cells, resembling micropapillary clusters, at a high magnification view. Of note, the definition of tumor STAS differs in invasive mucinous adenocarcinoma (IMA). The tumor cells of IMA show a goblet and/or columnar cell morphology with abundant intracytoplasmic mucin. Such tumor clusters are often observed in alveolar spaces filled with mucin products. The tumor spread through the mucus must be distinguished from tumor STAS. Thus, in IMA, the edge of the main tumor is defined as alveolar spaces not filled with tumor mucin. As other pathological factors, we investigated the presence of micropapillary components (> 5%), solid components (> 5%), and necrotic lesions (> 20%), as well as the tumor differentiation degree, in all resected tumor specimens. For adenocarcinomas, the degree of differentiation was established based on previously published criteria 12,13 with some modification, as follows: the lepidic, papillary, acinar subtypes were defined as well differentiated; tumors with micropapillary components, cribriform or solid pattern, or of the micropapillary subtype were classified as moderately differentiated; and the solid subtype or other subtypes with a reasonable amount of solid component as poorly differentiated. For squamous cell carcinoma, since there are no established criteria, we defined a three-tier category 10

12 based on the degree of nuclear atypia combined with the degree of keratinization. Roughly, well to moderately differentiated lesions were classified as the keratinizing type, while poorly differentiated tumors were defined as non-keratinizing and basaloid squamous cell carcinoma of the 2015 WHO classification. All large cell carcinomas, small cell carcinomas, and large cell neuroendocrine carcinomas were defined as poorly differentiated, and one typical carcinoid tumor was defined as well differentiated. The remaining cases, including IMA and adenosquamous carcinoma, were categorized as well or moderately differentiated based on the nuclear atypia and structural complexity. For each case, we reviewed 1 10 tumor slides. Statistical Analysis Statistical analysis was performed using SPSS Statistics 22 (IBM Corporation, Somers, NY). Student s t-test and the chi-square test were used for analysis of continuous and categorical variables, respectively. Relapse-free survival curves were calculated using the Kaplan-Meier method and compared using the log-rank test. The relapse-free survival rate was defined as the time from surgery to the first diagnosis of local and locoregional or distant recurrence, or until the last follow-up. All p values were based on two-tailed statistical analyses, and p values less than 0.05 were considered statistically significant. Ethical approval The study protocol was approved by the Medical Research Ethics Committee of National 11

13 Cancer Center (IRB approval No ), and all experiments were conducted in accordance with the Declaration of Helsinki. The requirement for informed consent was waived by the committee since our study was a retrospective review of patient records. 12

14 RESULTS Clinicopathological Features of Tumors Treated by Limited Resection In our study, a total of 508 patients met the inclusion criteria. The demographic, clinical, and pathologic features of these patients are shown in Table 1. The study patients included 248 males and 260 females, with a median age of 66 years (range, years). The rates of segmentectomy (n = 235, 46.3%) and wedge resection (n = 273, 53.7%) were comparable in both the intentional and compromised limited resection groups. Overall, compromised limited resection accounted for a slightly larger proportion of cases than intentional limited resection (n = 297, 58.5%). Most intentional limited resection cases were low-grade tumors (n = 135/211, 64.0%). The median tumor size was 1.4 cm (range, cm), and the median surgical margin was 1.8 cm (range, cm). In our study, there were 34/508 (6.7%) recurrent cases; these included 8 (23.5%) lung metastasis cases. Pathological Findings of Tumors Treated by Limited Resection The pathological evaluation results are summarized in Table 1. Adenocarcinoma constituted the most common histologic subtype of this study (n = 440, 86.6%), followed by squamous cell carcinoma (n = 44, 8.7%) and other types (n = 24, 4.7%). The adenocarcinomas included 107 adenocarcinomas in situ (AIS), 144 minimally invasive adenocarcinomas (MIA), 90 lepidic-predominant, 26 acinar-predominant, 50 papillary-predominant, 2 13

15 micropapillary-predominant, 7 solid-predominant, and 15 invasive mucinous. In the other histology type group, there were 7 small cell carcinomas, 7 large cell neuroendocrine carcinomas, 5 adenosquamous carcinomas, 4 large cell carcinomas, and 1 typical carcinoid tumor. Tumor STAS was present in 76 cases (15.0%), including in 8 squamous cell carcinomas. There were no cases of STAS in the patients with lepidic predominant adenocarcinoma, AIS, or MIA. In identifying tumor STAS, the diagnostic concordance rate (κ value) between the two observers was For the subtype of STAS (single, small, and large clusters), the diagnostic concordance rate was For the discordant cases, the two pathologists discussed until a consensus was reached. Recurrence Patterns after Limited Resection Among the total 508 cases, 34 recurrences (6.7%) were observed during a median follow-up period of 51 months. The period from operation to recurrence ranged from 4.8 to 85.6 months (median, 41.9 months). The observed recurrence patterns included local, locoregional, and distant recurrences in 8 (1.6%), 16 (3.2%), and 10 patients (2.0%), respectively. Risk Factors of Recurrence after Limited Resection We examined the risk factors for tumor recurrence. In terms of local recurrence, risk factor analysis using logistic regression revealed that a margin distance < 1.0 cm (hazard ratio [HR] 6.36, 95% confidence interval [CI] ; p = 0.02) and presence of tumor STAS (HR 14

16 18.37, 95% CI ; p < 0.001) were significantly associated with a higher risk of local recurrence after limited resection in both the univariate and multivariate analyses (Table 2). Especially, for the surgical margin, a margin distance < 1.0 cm was strongly associated with the risk of local recurrence, whereas no local recurrence occurred in tumors with a margin distance of > 2.0 cm, regardless of other factors, including tumor STAS (Figure 1). For locoregional recurrence, univariate analysis revealed that the presence of tumor STAS, tumor size, tumor grade, and lymph vessel, vascular, and pleural invasion were significantly associated with a higher recurrence risk. However, in the multivariate analysis, none of these factors remained significantly associated with a higher recurrence risk, except for tumor STAS and pleural invasion (Supplemental Table 1). Similarly, in terms of the risk of distant recurrence, tumor STAS, age, tumor grade, lymph vessel invasion, vascular invasion, and pleural invasion were significantly associated with a higher risk in the univariate analyses, whereas in the multivariate analysis, these factors were not significantly associated with the risk of recurrence, except for vascular and lymph vessel invasion (Table 3). Of note, in this cohort, there were many AIS and MIA cases. These cases are considered to have favorable prognoses; hence, we performed further analysis of 257 cases after excluding AIS and MIA. Among these 257 cases, 34 recurrences (13.2%) were observed. The prognostic analyses of this subgroup showed similar results to those of the total cases. That is, in terms of 15

17 local recurrence, risk factor analysis using logistic regression revealed a margin distance of < 1.0 cm (HR 5.07, 95% CI ; p = 0.033) and the presence of tumor STAS (HR 4.45, 95% CI ; p = 0.044) as significant factors in both the univariate and multivariate analyses. For locoregional recurrence, in the multivariate analysis, pleural invasion was found to be significantly associated with a higher recurrence risk. In terms of the risk of distant recurrence, only lymph vessel invasion was significantly associated with the risk of recurrence in the multivariate analysis. Of the 44 squamous cell carcinomas, the 8 STAS-positive cases showed non-significant trends of shorter relapse-free (p = 0.251, log-rank test) and overall survival durations (p = 0.127). We were unable to analyze the other histological types because of the small number of cases. Clinicopathological Features of Patients with Tumor STAS Tumor STAS was observed in 76 cases (15.0%). In the tumor STAS-positive patients, the small cluster subtype (n = 45, 58.2%) was the most prevalent subtype of the tumor STAS component, followed by the large nest (n = 19, 24.1%) and single cell (n = 12, 17.7%) subtypes. The proportions of poorly differentiated cancer (p = 0.027), lymphatic invasion (p < 0.001), and presence of micropapillary (p = 0.002) and solid components (p = 0.008) were greater in tumor STAS-positive patients than in tumor STAS-negative patients. No significant differences were observed in age, operation methods, tumor size, tumor margin, histology, or necrosis according 16

18 to the presence of tumor STAS (Table 4). 17

19 DISCUSSION Our study examined the prognostic factors after limited resection for primary lung cancer. Of note, we found that tumor margins of < 1.0 cm and the presence of tumor STAS were strongly associated with the risk of local recurrence. Tumor vessel invasion was the only significant factor affecting the risks of distant recurrence, while the presence of STAS did not demonstrate a significant correlation with distant recurrence. Although the surgical margin is considered a major factor influencing the risk of local recurrence, to date, there has been no clear evidence regarding the most appropriate surgical margin of limited resections. The National Comprehensive Cancer Network (NCCN) guidelines have recommended surgical margins of 2.0 cm or at least the size of the nodules. 7-9 Mohiuddin reported that increasing the margin distance to 1.5 cm significantly decreased the local recurrence risk in cases of wedge resection for small NSCLC. 20 On the other hand, Maurizi et al. suggested that the tumor margin did not influence the recurrence risk or survival rate in cases of complete resection for stage I NSCLC. 21 In our study, a margin distance < 1.0 cm was significantly associated with the local recurrence rate, indicating that ensuring tumor margins 1.0 cm should be a priority during limited resection in order to achieve local control. Moreover, in patients with a resection margin > 2.0 cm, no local recurrence was observed, regardless of the surgical operation, presence of tumor STAS, or other pathological factors. As a result, our data 18

20 showed high local control rates (5-year relapse-free and overall survival rates of 98.0% and 92.0%, respectively) compared with other reports, and support the validity of the NCCN guidelines. 20 From this point of view, in limited resection, we should try to ensure sufficient surgical margins of > 2.0 cm by palpation. Another prognostic risk factor for local recurrence in this study was the presence of tumor STAS. Herein, we found that tumor STAS was associated with a higher risk of local recurrence, similar to inadequate surgical margins. However, the presence of tumor STAS did not seem to influence the risk of distant recurrence. Kadota et al. reported the presence of STAS as a significant risk factor for recurrence in small lung adenocarcinomas treated with limited resection, 17 and Warth et al. reported that the presence of tumor STAS was associated with both reduced overall and disease-free survival in 674 completely resected adenocarcinomas. 19 Shiono and Yanagawa evaluated tumor STAS in surgically resected stage I lung adenocarcinoma and reported close correlations with poor prognosis and recurrence. 22 Further, Lu et al. reported that STAS in lung squamous cell carcinoma is an independent predictor of any recurrence and lung cancer-specific death. 23 Taken together, these reports support our results. On the other hand, interestingly, Kadota reported that the presence of tumor STAS was not a significant risk factor for recurrence in patients treated with lobectomy. Lobectomy has been the standard surgical procedure for clinical stage IA NSCLC since the 1995 report from the LCSG, 1 with the only 19

21 difference between lobectomy and limited resection being the tumor margin distance. Hence, although tumor STAS is a phenomenon of floating tumor cells in the air spaces, it might only influence the risk of local recurrence. Ensuring adequate surgical margins might reduce the effect of tumor STAS. On the other hand, if the tumor margin is < 1.0 cm or findings suggestive of STAS are observed, additional resection, including conversion to lobectomy, should be considered for good-risk patients. We should mention that there are several different terms to explain morphology similar to STAS, including tumor islands 24 and free tumor cluster. 25 These findings are also related to poor clinical outcomes, similar to STAS, so we presume that these different terms may be applied to express a very similar phenomenon of lung cancer. Further, despite our result that tumor STAS might be a prognostic factor, as suggested in previous reports, the pathological and molecular significance of STAS remain unclear. A pathological phenomenon similar to STAS was first reported in lung metastasis of colorectal cancer; Shiono et al. reported that ASFC was an independent prognostic factor in these patients. 16 That report suggested the molecular mechanisms of this factor as loss of cell-to-cell adhesion or anchorage-independent growth of cancer cells. In addition, the pathological features of IMA might be similar to those of STAS. The mucinous form is usually associated with the aerogenous spread of tumor cells, which is considered an invasive factor. 26, 27 Therefore, IMA has a poor prognosis in terms of its high local 20

22 recurrence. 26 However, studies with conflicting results also exist. Thunnissen reported that tumor STAS was an artefact secondary to the cut surface of the specimen. 28 In that report, STAS was observed in half of all resected adenocarcinomas and coincided with the frequency of spreading through a knife surface, a frequent finding in lung sections, not only in adenocarcinomas but also in squamous cell carcinomas and benign lung tissue. As above, although STAS is a phenomenon that was previously reported in metastatic lung tumors and some variant types, in ordinary lung cancer, it might be disregarded as an artefact. In clinical practice, the difference between real STAS and such an artefact is difficult to distinguish, although the so-called STAS findings can be easily recognized by histological analysis on hematoxylin and eosin-stained slides. STAS seems to be an important finding when predicting the risk of local recurrence using limited resected material with specimens that were fixed and cut uniformly. The above-mentioned confusions might be due to the name of STAS, as well as the lack of biological understanding on how STAS occurs. Currently, there is no strong biological evidence that STAS cancer cells can survive within the air space and establish metastatic foci outside of the main tumor. Based on our general knowledge of cancer biology, the cancer cells need feeding to survive and need to settle on an appropriate soil to create metastatic foci. It seems to be more difficult for cancer cells to settle on the surface of epithelial than in the mesenchymal tissue. We presume that STAS is a morphological representation of 21

23 cancer progression. One possible scenario is as follows: excessed dysregulated cancer cells can form a cluster, some of which might achieve anoikis-resistance, and the subsequent loss of cellular maturation may induce the discohesion of cancer cells. Such crushed small fragments of cancer cells look like spreading through the air space; however, we cannot predict the fate of these cells in terms of whether they can form metastasis by themselves or not. Considering recently published clinical data, as well as the results of our study, the STAS phenomenon can be concluded to be a recognizable pathological finding, indeed relating to a worse clinical outcome. In addition to the clinical significance of STAS, from the viewpoint of the strict biological meaning, there is controversy regarding whether the metastatic mechanism could be an artefact. Furthermore, whether the degree of STAS is reproducible among different institutions remains unclear. As mentioned above, as STAS could be a confounding factor of other biological features of the tumor, some pathologists still feel uncomfortable to use the term spread through air spaces for this morphological finding. Thus, further studies are needed in the future to clarify these issues. Moreover, similar to for vascular, lymphatic, and pleural invasion, which can be confirmed using immunohistochemical staining, an easy way to diagnose real STAS is also needed. For that purpose, the molecular mechanisms of STAS need to be urgently clarified. These are some limitations of our study. First, we only included limited resected 22

24 pathological stage 0 and I cases, and the information about the lymph node involvement status, an important variable, was thus insufficient, since we could not obtain enough standardized data of our limited resected cases. Second, there were several cases in which it was difficult to judge whether the second tumors were second primary tumors or intra-pulmonary metastatic tumors. We might have missed some second primary tumor cases that we coded as intrapulmonary metastasis, and vice versa. While these cases are likely few, it should be mentioned that these cases could affect the results of our study. Lastly, due to the small number of distant recurrence events (2%), the calculation power to detect a difference in this cohort might have been insufficient. In conclusion, in cases of limited resection for primary lung cancer, increasing the margin distance to over 1 cm is significantly associated with a decreased risk of local recurrence. Further, the presence of tumor STAS might be a pathologic prognostic factor for lung cancer patients who have undergone limited resection. However, the pathological and molecular significance of STAS remain to be clarified. 23

25 Acknowledgement. This work was supported in part by Grant-in-Aid for Scientific Research (C) Grant Number and AMED16ck h0003. We appreciate Ms. Sachiyo Hasegawa for her excellent secretary work and Dr. Aya Kuchiba for her expert statistical advice. 24

26 REFERENCES 1. Ginsberg RJ, Rubinstein LV. Randomized trial of lobectomy versus limited resection for T1 N0 non-small cell lung cancer. Lung Cancer Study Group. Ann Thorac Surg 1995; 60: Kodama K, Higashiyama M, Okami J, et al. Oncologic Outcomes of Segmentectomy versus lobectomy for clinical T1aN0M0 non-small cell lung cancer. Ann Thorac Surg 2016; 101: Tsutani Y, Miyata Y, Nakayama H, et al. Appropriate sublobar resection choice for ground glass opacity-dominant clinical stage IA lung adenocarcinoma: wedge resection or segmentectomy. Chest 2014; 145: Koike T, Koike T, Yamato Y, et al. Prognostic predictors in non-small cell lung cancer patients undergoing intentional segmentectomy. Ann Thorac Surg. 2012; 93: Brown LM, Louie BE, Jackson N, et al. Recurrence and survival after segmentectomy in patients with prior lung resection for early-stage non-small cell lung cancer. Ann Thorac Surg. 2016; 102: El-Sherif A, Fernando HC, Santos R, et al. Margin and local recurrence after sublobar resection of non-small cell lung cancer. Ann Surg Oncol. 2007; 14: Kodama K, Doi O, Higashiyama M, et al. Intentional limited resection for selected patients 25

27 with T1N0M0 non-small cell lung cancer. J Thorac Cardiovasc Surg 1997; 114: Yoshikawa K, Tsubota N, Kodama K, et al. Prospective study of extended segmentectomy for small lung tumors: the final report. Ann Thorac Surg 2002; 73: Sawabata N, Ohta M, Matsumura A, et al. Optimal distance of malignant negative margin in excision of nonsmall cell lung cancer: a multicenter prospective study. Ann Thorac Surg. 2004; 77: Warth A, Muley T, Meister M, et al. The novel histologic International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society classification system of lung adenocarcinoma is a stage-independent predictor of survival. J Clin Oncol. 2012; 30: Hung JJ, Jeng WJ, Chou TY, et al. Prognostic value of the new International Association for the Study of Lung Cancer/American Thoracic Society/European Respiratory Society lung adenocarcinoma classification on death and recurrence in completely resected stage I lung adenocarcinoma. Ann Surg. 2013; 258: Yoshizawa A, Motoi N, Riely GJ, et al. Impact of proposed IASLC/ATS/ERS classification of lung adenocarcinoma: prognostic subgroups and implications for further revision of staging based on analysis of 514 stage I cases. Mod Pathol. 2011; 24: Yoshizawa A, Sumiyoshi S, Sonobe M, et al. Validation of the IASLC/ATS/ERS lung 26

28 adenocarcinoma classification for prognosis and association with EGFR and KRAS gene mutations: analysis of 440 Japanese patients. J Thorac Oncol. 2013; 8: Nitadori J, Bograd AJ, Kadota K, et al. Impact of micropapillary histologic subtype in selecting limited resection vs lobectomy for lung adenocarcinoma of 2cm or smaller. J Natl Cancer Inst. 2013; 105: Travis WD, Brambilla E, Burke AP, et al. WHO Classification of tumours of the lung, pleura, thymus and heart, 4th edition. Lyon: IARC; Shiono S, Ishii G, Nagai K, et al. Histopathologic prognostic factors in resected colorectal lung metastases. Ann Thorac Surg 2005; 79: Kadota K, Nitadori JI, Sima CS, et al. Tumor spread through air spaces is an important pattern of invasion and impacts the frequency and location of recurrences following limited resection for small stage I lung adenocarcinomas. J Thorac Oncol. 2015; 10: Leslie HS, Mary KG, Christian W. TNM classification of malignant tumours, 7th Edition. New York: Wiley; Warth A, Muley T, Kossakowski CA, et al. Prognostic Impact of Intra-alveolar Tumor Spread in Pulmonary Adenocarcinoma. Am J Surg Pathol. 2015; 39: Mohiuddin K, Haneuse S, Sofer T et al. Relationship between margin distance and local recurrence among patients undergoing wedge resection for small (<2 cm) non small cell 27

29 lung cancer. J Thorac Cardiovasc Surg 2014; 147: Maurizi G, D'Andrilli A, Ciccone AM et al. Margin distance does not influence recurrence and survival after wedge resection for lung cancer. Ann Thorac Surg 2015; 100: Shiono S, Yanagawa N. Spread through air spaces is a predictive factor of recurrence and a prognostic factor in stage i lung adenocarcinoma. Interact Cardiovasc Thorac Surg 2016; 23: Lu S, Tan KS, Kadota K, et al. Spread through air spaces (stas) is an independent predictor of recurrence and lung cancer-specific death in squamous cell carcinoma. J Thorac Oncol 2017; 12: Onozato ML, Kovach AE, Yeap BY, et al. Tumor islands in resected early-stage lung adenocarcinomas are associated with unique clinicopathologic and molecular characteristics and worse prognosis. Am J Surg Pathol 2013; 37: Morimoto J, Nakajima T, Suzuki H, et al. Impact of free tumor clusters on prognosis after resection of pulmonary adenocarcinoma. J Thorac Cardiovasc Surg 2016; 152:64-72.e Casali C, Rossi G, Marchioni A, et al. A single institution based retrospective study of surgically treated bronchioloalveolar adenocarcinoma of the lung: clinicopathologic analysis, molecular features, and possible pitfalls in routine practice. J Thorac Oncol 2010; 5:

30 27. Manning JT Jr, Spjut HJ, Tschen JA. Bronchioloalveolar carcinoma: the significance of two histopathologic types. Cancer 1984; 54: Thunnissen E, Blaauwgeers HJ, de Cuba EM, et al. Ex Vivo Artifacts and Histopathologic Pitfalls in the Lung. Arch Pathol Lab Med. 2016; 140:

31 FIGURE LEGENDS Figure 1a, 1b, and 1c Relapse-free survival curves for local recurrence of patients undergoing limited resection for primary lung cancer according to margin distance (Fig. 1a and 1b) and tumor spread through air spaces (STAS) (Fig. 1c). Figure 2 Representative images of tumor spread through air spaces (STAS)_in adenocarcinoma (a-d), squamous cell carcinoma (e, f), and small cell carcinoma (g, h). STAS was found as a single cell (b), small cell cluster (b, h), or large nests (d, h). STAS was located near (c, e) or far (a, g) from the edge of the tumor. The right column images (b, d, f, h) are the high-power views of the boxed areas. The asterisk indicates at least one free alveolar space between the STAS and main tumor (hematoxylin and eosin stain; a, e: bar = 0.2 mm; b, d, h: bar = 0.05 mm; c, g: bar = 0.5 mm; f: bar = 0.1 mm). 30

32 TABLE 1. Patient Characteristics Variables n (%) Total 508 Gender Female Male Age (y) > limited Pulmonary Resection Intentional LR Compromised LR Operation Method Segmentectomy Wide Wedge Resection Tumor Size (mm) > Margin Distance (mm) > Histologic Type Adenocarcinoma AIS MIA lepidic acinar papillary micropapillary 2 0.3

33 solid Invasive mucinous Squamous Cell Carcinoma Others Vascular Invasion Negative Positive Lymph Vessel Invasion Negative Positive Pleural Invasion Negative Positive Tumor STAS Negative Positive Abbreviations: LR, limited resection; AIS, adenocarcinoma in situ; MIA, minimally invasive adenocarcinoma; STAS, spread through air spaces. Others include 7 small cell carcinoma, 7 large cell neuroendocrine carcinoma, 5 adenosquamous carcinoma, 4 large cell carcinoma and 1 typical carcinoid tumor.

34 TABLE 2. Univariate and Multivariate Analysis of Local Recurrence for Limited Resection Reference Univariate Analysis Multivariate Analysis HR 95% CI p value HR 95% CI p value Tumor Margin < 1.0 cm STAS Negative < Age < Tumor Grade WD/MD&PD Abbreviations: HR, hazard ratio; CI, confidence interval; STAS, spread through air spaces.

35 TABLE 3. Univariate and multivariate analysis of Distant Recurrence for Limited Resection Reference Univariate Analysis Multivariate Analysis HR 95% CI p value HR 95% CI p value Tumor Margin < 1.0 cm STAS Negative Age < Tumor Grade WD/MD&PD Pleural Invasion Negative Lymph Vessel Invasion Negative < Vascular Invasion Negative < Abbreviations: HR, hazard ratio; CI, confidence interval; STAS, spread through air spaces.

36 TABLE 4. Clinicopathological Correlations for Tumor STAS STAS Negative STAS Positive Variables p Sex Male Female Age (Year) Median Range Smoking Never Former/Present Operation Segmentectomy Wedge Resection Tumor Size (cm) Median Range Tumor Margin (cm) Mean Range Histology AD SQ Other 14 7 Tumor Grade W/D M/D P/D STAS component Single Cells - 12 Small Cluster - 45 Large Nest - 19 Necrosis Negative Positive Solid Component Negative Positive 54 33

37 Micropapillary Component Negative Positive Vascular Invasion Negative <0.001 Positive Lymph Vessel Invasion Negative <0.001 Positive Pleural Invasion Negative Positive <0.001 Abbreviations: STAS, spread through air spaces; AD, adenocarcinoma; SQ, squamous cell carcinoma.

38

39 AC C EP TE D M AN U SC RI PT

40 本文献由 学霸图书馆 - 文献云下载 收集自网络, 仅供学习交流使用 学霸图书馆 ( 是一个 整合众多图书馆数据库资源, 提供一站式文献检索和下载服务 的 24 小时在线不限 IP 图书馆 图书馆致力于便利 促进学习与科研, 提供最强文献下载服务 图书馆导航 : 图书馆首页文献云下载图书馆入口外文数据库大全疑难文献辅助工具