Skip metastasis and hidden N2 disease in lung cancer: how successful is mediastinal dissection?

Metastatic Patterns of Mediastinal Lymph Nodes in Small-Size Non-small Cell Lung Cancer (T1b)

Background: Lymph node metastasis (LNM) status is critical to the treatment. Fewer studies has focused on LNM in patients with small-size non-small cell lung cancer (NSCLC). This study aims to investigate clinicopathological characteristics associated with skip N2 (SN2) and non-skip N2 (NSN2) metastasis, and their metastatic patterns in NSCLC with tumor size of 1–2 cm.

Methods: We reviewed the records of NSCLC patients with tumor size of 1–2 cm who underwent lobectomy with systematic lymph node dissection (LND) between January 2013 and June 2019. Clinical, radiographical, and pathological characteristics were compared among N1, SN2, and NSN2 groups. Metastatic patterns of mediastinal lymph node were analyzed based on final pathology.

Results: A total of 63 NSCLC patients with tumor size of 1–2 cm were staged as pN2, including 25 (39.7%) SN2 and 38 (60.3%) NSN2. The incidence rates of SN2 and NSN2 were 2.8% (25/884) and 4.3% (38/884), respectively. For all clinicopathological characteristics, no significant difference was observed among the groups of N1, SN2, and NSN2. For the tumor located in each lobe, specific nodal drainage stations were identified: 2R/4R for right upper lobe; 2R/4R and subcarinal node (#7) for right middle lobe and right lower lobe; 4L and subaortic node (#5) for left upper lobe; #7 for left lower lobe. However, there were still a few patients (10.9%, 5/46) had the involvement of lower zone for tumors of upper lobe and the involvement of upper zone for lower lobe.

Conclusions: SN2 occurs frequently in patients with small-size NSCLC. Whether lobe-specific selective LND is suitable for all small-size patients deserves more studies to confirm. Surgeons should be more careful when performing selective LND for tumors located in the lower and upper lobes.

Single-station skip-N2 disease: good prognosis in resected non-small-cell lung cancer (long-term results in skip-N2 disease)

OBJECTIVES

Pathological N2 (pN2) involvement has a negative impact on prognosis in patients operated on due to non-small-cell lung cancer (NSCLC). pN2 disease may cause skip (pN0N2) or non-skip (pN1N2) metastases with pathological N1 (pN1) involvement. The effect of pN2 subgroups on prognosis is still controversial. We analysed the effect of pN1 disease and single-station pN2 disease subgroups on survival outcomes.

METHODS

The medical records of patients who underwent anatomical lung resection due to NSCLC at a single centre between January 2007 and January 2017 were prospectively collected and retrospectively analysed. Operative mortality, sublobar resection, Stage IV disease, incomplete resection and carcinoid tumour were considered exclusion criteria. After histopathological examination, the prognosis of patients with pN1, pN0N2 and pN1N2 was compared statistically. Univariable and multivariable analyses were made to define independent risk factors for overall survival rates.

RESULTS

The mean follow-up time for 358 patients with 228 pN1 disease (63.7%), 59 pN0N2 disease (16.5%) and 71 pN1N2 disease (19.8%) was 40.4 ± 30.4 months. Median and 5-year overall survival rates for pN1, pN0N2 and pN1N2 diseases were 73.6 months [95% confidence interval (CI) 55.5-91.7] and 54.1%, 60.3 months (95% CI 26.8-93.8) and 51.2%, 20.8 months (95% CI 16.1-25.5) and 21.5%, respectively. The survival CIs of pN1 and pN0N2 diseases were similar, and the survival rates of these 2 groups were significantly better than those with pN1N2 (P < 0.001, P = 0.001, respectively). In multivariable analysis, patients over the age of 60 [hazard ratio (HR) 2.13, P < 0.001], patients not receiving adjuvant therapy (HR 1.52, P = 0.01) and patients with pN1N2 disease (HR 2.91, P < 0.001) had a poor prognosis.

CONCLUSIONS

Advanced age, not receiving adjuvant therapy and having pN1N2 disease are negative prognostic factors in patients with nodal involvement who underwent curative resection due to NSCLC. The overall survival and recurrence-free survival rates of pN1 disease and single-station pN0N2 disease are similar, and they have significantly better survival rates than pN1N2 disease. Based on these results, surgical treatment may be considered an appropriate choice in patients with histopathologically diagnosed single-station skip-N2 disease.

[Survival Analysis of Stage I Non-small Cell Lung Cancer Patients Treated with Da Vinci Robot-assisted Thoracic Surgery]

背景与目的

达芬奇机器人手术系统在胸外科的应用日益广泛，本研究旨在探讨经达芬奇机器人手术治疗Ⅰ期非小细胞肺癌（non-small cell lung cancer, NSCLC）患者的疗效。

方法

回顾2012年1月-2017年12月于我科行手术治疗的Ⅰ期NSCLC患者347例，依据手术方式分为机器人（robot-assisted thoracic surgery, RATS）组134例及腔镜（video-assisted thoracic surgery, VATS）组213例。比较两组患者围术期一般指标（术中出血量、术后引流量、术后带管时间、术后住院时间、淋巴结清扫状况），分析患者生存状况（overall survival, OS）、无进展生存状况（disease free survival, DFS）及相关影响因子。

结果

机器人组与腔镜组术中出血量[(49±39) mL vs (202±239) mL]、术后引流量[Day 1: (248±123) mL vs (350±213) mL; Day 2: (288±189) mL vs (338±189) mL]比较，机器人组均少于腔镜组（P < 0.05）；术后带管时间[(10±5) d vs (11±8) d]及住院时间[(13±6) d vs (14±9) d]两组患者无明显差异（P > 0.05）。机器人组与腔镜组的淋巴结清扫组数[（5±2）组vs（4±2）组]及淋巴清扫数量[（18±9）枚vs（11±8）枚]比较，机器人组均优于腔镜组（P < 0.05）。机器人组与腔镜组生存状况比较[1年生存率：97.3% vs 96%、3年生存率：89.8% vs 83.1%、5年生存率：87.5 % vs 70.3%，平均生存时间（month）：61 vs 59]，两组无统计学差异（P > 0.05）。无进展生存状况：机器人组与腔镜组比较[1年无进展生存率：93.7% vs 91.3%、3年无进展生存率：87.7% vs 68.4%、5年无进展生存率：87.7% vs 52.5%，平均无进展生存时间（month）：61 vs 50]，机器人组明显优于腔镜组（P < 0.05）。单因素分析显示，淋巴结清扫数量是患者生存状况的影响因子；肿瘤直径、手术方式、淋巴结清扫组数、淋巴结清扫数量为患者无进展生存状况的影响因子。多因素分析显示生存状况无独立影响因子，肿瘤直径及手术方式为无进展生存状况的独立影响因子。

结论

达芬奇机器人Ⅰ期非小细胞肺癌患者术后生存状况与腔镜手术无差异，但无进展生存状况优于腔镜手术；达芬奇机器人手术淋巴结清扫更彻底，同时术中出血量更少。

Risk factors for relapse of resectable pathologic N2 non small lung cancer and prediction model for time-to-progression

Background

Pathologic N2 non-small-cell lung cancer (NSCLC) was demonstrated with poor survival among literature. In this study, we retrospectively reviewed patients with pathologic N2 NSCLC and received anatomic resection (i.e. lobectomy) for further relapse risk factor analysis. The aim of this study is to identify the clinicopathologic factors related to relapse among resectable N2 NSCLC patients and to help clinicians in developing individualized follow up program and treatment plan.

Method

From January 2005 to July 2012, 90 diagnosed pathologic N2 NSCLC patients were enrolled into this study. We retrospectively reviewed medical records, image studies, and pathology reports to collect the patient clinico-pathologic factors.

Result

We identified that patients with visceral pleural invasion (p = 0.001) and skip metastases along mediastinal lymph node (p = 0.01) had a significant relationship to distant and disseminated metastases. Patients who had 2 or more risk factors for relapse demonstrated poor disease free survival than those who had less than 2 risk factors (p = 0.02). The number of involved metastatic area were significantly influential to the period of time-to-progression. The duration of time-to-progression was correlated with square of number of involved metastatic areas. (Pearson correlation coefficient = −0.29; p = 0.036).

Conclusion

Relapse risk factors of resectable pathologic N2 NSCLC patient after anatomic resection were visceral pleural invasion, skip mediastinal lymph node involvement, and the receipt of neoadjuvant therapy. The duration of time-to-progression was correlated with square of number of involved metastatic areas.

Is lower zone mediastinal nodal dissection always mandatory for lung cancer in the lower lobe?

PURPOSE

Dissection of the lower zone mediastinal nodes is mandatory during systematic nodal dissection for lung cancer. However, the significance of lower zone lymph node metastasis (LZM) in lung cancer remains unclear. Therefore, we aimed to identify the predictive factors for LZM in patients with lower lobe lung cancer.

METHODS

A retrospective study was conducted on 257 patients with lower lobe lung cancer, in whom pulmonary resection and mediastinal nodal dissection were performed between 2009 and 2013. The radiological factors on thin-section computed tomography scans (TSCT) and several conventional clinical factors were evaluated as possible predictors of LZM.

RESULTS

Twenty (7.8 %) patients exhibited LZM. The majority of the tumors were especially located in segment 10 (50 %). All patients showed a solid appearance on TSCT. In a univariate analysis, the tumor location, a solid appearance and the clinical T factor significantly predicted LZM (p = 0.011, 0.005, 0.018). Furthermore, based on a multivariate analysis, the tumor location in segment 10 significantly predicted LZM in patients with lower lobe solid lung cancer (p = 0.031).

CONCLUSION

The appropriate surgical strategy for lower zone lymph node dissection should be selected based on the tumor location and the findings of TSCT, due to the high frequency of LZM (19.6 %), especially in patients with pure solid lung cancer in segment 10.

Detection of pleural lymph flow using indocyanine green fluorescence imaging in non-small cell lung cancer surgery: a preliminary study

PURPOSE

Lymphatic spread of lung carcinoma to the mediastinum is a key determinant of prognosis. The lymph flow often carries metastases from the pulmonary segment directly into the mediastinal lymph nodes, without passing through the hilar nodes. This phenomenon is termed as "skip metastasis." This study investigated the subpleural lymphatic flow to the mediastinum using indocyanine green (ICG) with a near-infrared fluorescence imaging system.

METHODS

Seventeen patients with lung cancer were enrolled in this study. A 0.3 ml sample of solution containing the fluorescent dye ICG (5 mg/ml) was injected into subpleural sites near the primary tumor. Fluorescence imaging was used to monitor the flow of ICG-containing lymph from the injection site for 5 min. The relationship between the anatomical segment of the primary tumor and the lymphatic flow was assessed.

RESULTS

The lymphatic vessels draining from the injection site were revealed by the bright ICG fluorescence in 14 of the patients (82.4 %). A direct lymphatic flow to the mediastinum was confirmed in 3 of those 14 (21.4 %).

CONCLUSIONS

These findings confirm the direct flow of lymph to the mediastinum without passage through the hilum pulmonis intraoperatively. These preliminary results may provide a valuable clue for further investigations of the mechanisms underlying skip metastasis.

Surgical management of non-small cell lung cancer with mediastinal lymphadenopathy

Several issues regarding the surgical management of N2 disease remain unresolved. First, the anatomical attribution of a mediastinal nodal station, especially in certain areas (i.e., azygos recess), is a source of continuous debate. Second, the presence of occult N2, single or multilevel N2, bulky N2, the skip phenomenon and the observation of a different prognostic outlook for specific mediastinal nodal stations are all elements of discussion that cannot clarify whether stage IIIA-N2 non-small cell lung cancer is indeed a locally, albeit advanced, manifestation of the disease or the prodrome of an actual systemic dissemination. In this subset of patients lies the challenge for multidisciplinary treatment modalities, where the surgical role needs to be further defined in the context of an integrated collaborative effort with the medical oncologist and the radiotherapist.

Skip mediastinal nodal metastases in the IIIa/N2 non-small cell lung cancer

INTRODUCTION

To study the incidence and characteristics of mediastinal nodal metastases without N1 nodal metastases (skip N2 metastases) in patients with resected pIII/A/N2 non-small cell lung cancer.

METHODS

A total of 323 non-small cell lung cancer patients who underwent radical surgical resection with a systematic mediastinal nodal dissection in 4-year period (2000-2003) were retrospectively reviewed. The 85 patients (26%) at stage IIIA/N2 (pN2+) were grouped according to their skip metastases status. Patient data were statistically analyzed.

RESULTS

Skip N2 metastases were found in 21 patients (25%) without N1 nodal involvement. The postoperative survival for skip N2 disease was almost the same as that for pN2 disease with N1 nodal involvement. The incidence of N2 metastases seemed to be more frequent in adenocarcinoma patients (p < 0.005), but skip N2 metastases were significantly higher (p < 0.001) in squamous cell carcinoma patients. Although skip metastases involved more often upper mediastinal lymph nodes and one station level, the difference was not found statistically significant (p < 0.227). Complication rate showed no difference between analyzed groups of patients.

CONCLUSIONS

Sample mediastinal lymphadenectomy may not be appropriate in surgery for non-small cell lung cancer because skip metastases were found in 25% of patients without N1 nodal involvement.

The IASLC Lung Cancer Staging Project: Proposals for the Revision of the N Descriptors in the Forthcoming Seventh Edition of the TNM Classification for Lung Cancer

INTRODUCTION

Accurate staging of lymph node involvement is a critical aspect of the initial management of nonmetastatic non-small cell lung cancer (NSCLC). We sought to determine whether the current N descriptors should be maintained or revised for the next edition of the international lung cancer staging system.

METHODS

A retrospective international lung cancer database was developed and analyzed. Anatomical location of lymph node involvement was defined by the Naruke (for Japanese data) and American Thoracic Society (for non-Japanese data) nodal maps. Survival was calculated by the Kaplan-Meier method, and prognostic groups were assessed by Cox regression analysis.

RESULTS

Current N0 to N3 descriptors defined distinct prognostic groups for both clinical and pathologic staging. Exploratory analyses indicated that lymph node stations could be grouped together into six "zones": peripheral or hilar for N1, and upper or lower mediastinal, aortopulmonary, and subcarinal for N2 nodes. Among patients undergoing resection without induction therapy, there were three distinct prognostic groups: single-zone N1, multiple-zone N1 or single N2, and multiple-zone N2 disease. Nevertheless, there were insufficient data to determine whether the N descriptors should be subdivided (e.g., N1a, N1b, N2a, N2b).

CONCLUSIONS

Current N descriptors should be maintained in the NSCLC staging system. Prospective studies are needed to validate amalgamating lymph node stations into zones and subdividing N descriptors.

Intentional limited resection for small peripheral lung cancer based on intraoperative pathologic exploration

OBJECTIVE

The aim of this study was to assess the adequacy of our intentional limited resection for small peripheral lung cancer based on intraoperative pathologic exploration.

METHODS

Patients who had stage IA non-small cell lung cancer (NSCLC) with a maximum tumor diameter of 2 cm or less were candidates for limited resection. If bronchioloalveolar carcinoma (BAC) was suspected on computed tomography and intraoperative pathologic exploration revealed the lesion as BAC without foci of active fibroblastic proliferation (Noguchi type A and B), wedge resection was performed. If the tumor was not suspected of being Noguchi type A or B, extended segmentectomy with intraoperative lymph node exploration was performed.

RESULTS

Limited resection was performed in 34 patients, wedge resection in 14, and extended segmentectomy in 20. The median follow-up period after wedge resection was 36 months, and all patients are alive with no signs of recurrence. The median follow-up period after extended segmentectomy was 54 months. No local recurrences were found, but distant metastasis was diagnosed in one patient. The 5-year survival rate after extended segmentectomy was 93%. In the same period, lobectomy was performed in 57 patients with stage IA NSCLC with a maximum tumor diameter of 2 cm or less, and the 5-year survival rate was 84%. There were no significant differences in 5-year survival between extended segmentectomy and lobectomy.

CONCLUSIONS

Careful selection of patients based on high-resolution computed tomography findings and intraoperative pathologic exploration makes intentional limited resection an acceptable option for the treatment of small peripheral NSCLC.

Analysis of risk factors for skip lymphatic metastasis and their prognostic value in operated N2 non-small-cell lung carcinoma

BACKGROUND

The aim of this study is to report a series and to analyze risk factors for skip lymphatic metastasis an their prognostic value in operated N2 non-small-cell lung carcinoma.

METHODS

From 1997 to 2002, 142 patients classified pN2 were included in the study. Tumours were classified according to the TNM classification. Skips metastases were defined by the cases of N2 disease without lobar and interlobar and hilar lymph node involvement. A skip (+) and a skip (-) group were defined. Characteristics of tumours, ganglionar involvement and survival were analysed in both groups.

RESULTS

Forty-two patients fulfilled the criteria for skip metastasis. The average number of mediastinal lymph nodes resected by patient was similar in both groups, whereas more intrapulmonary nodes were dissected in the skip (-) group (4.7 +/- 3 vs 3 +/- 3; p < 0.002). The ratio of involved to resected lymph nodes was 0.47 +/- 0.27 in the skip (-) group vs 0.23 +/- 0.20 in the skip (+) group (p < 0.0001). In the skip (+) group, 85% of the patients presenting with a right upper lobe tumour had involvement of the superior mediastinal lymph nodes against 40% in the skip (-) group. The 5-year survival rate was 48% in the skip (-) group vs 37% in the skip (+) group (p = 0.49). In multivariate analysis, incomplete resection, tumour size, extended resection and pT were significant prognostic factors.

CONCLUSIONS

Skip metastasis are frequent in non-small-cell lung cancer and complete dissection of hilar and mediastinal lymph nodes should remain the surgical standard procedure for this disease. However, skip metastasis are not an independent prognostic factor in survival.

EXTENT OF MEDIASTINAL LYMPH NODE DISSECTION FOR CLINICAL T1 NON-SMALL CELL LUNG CANCER

The present study was designed to determine the extent of lymph node dissection for clinical T1 non-small cell lung cancer without negatively influencing curability. The study included 192 cases with clinical T1 non-small cell lung cancers who underwent lobectomy with mediastinal lymphadenectomy. Among 69 cases with right upper lobe tumors, metastasis was found in subcarinal lymph node in one case only. No metastasis was found in subcarinal node in cases free of metastasis in hilar and/or superior mediastinal nodes. Among 33 cases with right lower lobe tumors, metastasis was detected in the superior mediastinal node only in cases with metastasis in hilar and/or subcarinal nodes. Among 51 cases with left upper lobe tumors, no metastasis was found in the subcarinal node. Among 22 cases with left lower lobe tumors, metastasis was found in the superior mediastinal nodes only in cases with metastasis in hilar and/or subcarinal nodes. We propose the following scheme for the extent of mediastinal node dissection. Dissection of mediastinal node for clinical T1 non-small cell lung cancer cannot be omitted. But, 1) for upper lobe tumors, subcarinal lymphadenectomy could be omitted if no metastasis is found in hilar and superior mediastinal nodes based on gross and microscopic examination of frozen sections. 2) Similarly, for lower lobe tumors, superior mediastinal lymphadenectomy could be omitted if no metastasis is detected in the hilar and subcarinal nodes.

Skip metastasis in nonsmall cell lung carcinoma

BACKGROUND

Skip metastasis to mediastinal lymph nodes is a prognostic factor for patients with nonsmall cell lung carcinoma (NSCLC). Little is known about the biologic behavior of tumors with noncontinuous spread to the mediastinal lymph nodes. In patients with pN2 skip metastases, micrometastases to N1 lymph nodes, which only mimic skip metastases, have not been investigated.

METHODS

In a retrospective study, the authors analyzed the primary tumor specimens from 45 patients with pN2 NSCLC (18 patients had squamous cell carcinomas, 23 had adenocarcinomas, and 4 had large cell carcinomas). They immunohistochemically evaluated the expression of p21, p53, MUC-1, Bcl-2, c-ErbB-2, and E-cadherin. Survival rates and biomarker expression levels were compared between patients with pN2 disease and infiltration of N1 lymph nodes (without skip metastasis [n = 28]) and patients with pN2 disease without N1 infiltration (with skip metastasis [n = 17]). To evaluate micrometastasis in the pN1 lymph nodes of 17 patients with skip metastases, lymph nodes were stained using the anticytokeratin antibody, AE1/AE3.

RESULTS

The 5-year survival rate of patients with skip metastases was 41%, compared with 14% for patients without skip metastases (P = 0.019). In a multivariate analysis, the incidence of skip metastases did not vary significantly according to gender, age, histology, pT status, or cM status. Three skip-positive patients (17.6%) had micrometastatic tumor involvement of pN1 lymph nodes. After adding these patients to the group of patients without skip metastases, there was still a significant difference in survival between the two groups. p53, MUC-1, c-ErbB-2, and E-cadherin expression levels in primary tumor specimens were not significantly different in patients with continuous metastasis and patients with skip metastases. Patients with skip metastases expressed lower levels of p21 (P = 0.026), whereas Bcl-2 expression levels were considerably higher (P = 0.019) compared with the corresponding levels in patients without skip metastases.

CONCLUSIONS

Patients with NSCLC and pN2 skip metastases have a more favorable prognosis than do patients with pN2 disease without skip metastases. Tumor specimens from these patients exhibit elevated expression of the antiapoptosis gene BCL2 and lower expression levels of p21 relative to patients with pN2 disease without skip metastases. Micrometastases occurred in 3 of 17 (17.6%) patients with pN2 disease and skip metastases diagnosed by routine histopathology.

Tumor dimension and prognosis in surgically treated lung cancer: for intentional limited resection

Tumors with a maximum dimension of 3 cm are categorized as T1, whereas those greater than 3 cm are T2 by TNM classification. Some physicians suggest that early-stage peripheral lung cancer should have a maximum tumor diameter of 2 cm and that limited surgery (segmentectomy without lymph node dissection) is acceptable for the patients. In this study, the relationship between the tumor dimension and prognosis was analyzed in 207 patients with surgically treated primary non-small-cell lung cancer (SCLC). The 5-year survival rate of those with tumors 3 cm or less and without lymph node (LN) metastases was 86%, which was significantly higher than that of those with tumors more than 3 cm and without hilar and mediastinal LN metastases (65%) (p < 0.05). However, 33% of the patients with tumors 3 cm or less had LN metastases, and the 5-year survival rate did not differ between those with tumors 3 cm or less (60%) and those with tumors more than 3 cm (54%). Twenty-eight percent of patients with tumors 2 cm or less had LN metastases, and the 5-year survival rate of the patients with tumors 2 cm or less was 62%. The 5-year survival rate of those with tumors 2 cm or less and without LN metastases was 88%. Forty-six patients with tumors 2 cm or less included 5 cases with an intrapulmonary metastasis in the same lobe (11%). In conclusion, a size of 3 cm is an appropriate boundary as the T factor. Because those with tumors 2 cm or less have a relatively high percentage of LN metastases, intraoperative frozen sections of LN should be considered for those undergoing limited surgery for primary non-SCLCs 2 cm or less. Intrapulmonary metastases also should be considered for those undergoing limited surgery even if the maximum dimension of the primary tumor is less than 2 cm.

Immunohistochemical evidence that P-glycoprotein in non-small cell lung cancers is associated with shorter survival

The expression of P-glycoprotein in 159 non-small cell lung cancers was immunohistochemically examined using a monoclonal antibody (MoAb C219). A total of 93 (60%) cancers were found to be positive for P-glycoprotein. The 5-year survival rates of patients with P-glycoprotein (P-gp+) and those without P-glycoprotein (P-gp-) were 47.6% and 73.6%, respectively (P < 0.05). According to a univariate analysis, P-gp+ was associated with a poor prognosis for males, those with stage I cancer, those who underwent complete resection, and those with adenocarcinoma or squamous cell carcinoma. A multivariate study using the Cox regression analysis indicated that the expression of P-glycoprotein is useful for predicting the prognosis. Among 24 patients who underwent complete resection and postoperative adjuvant chemotherapy, 18 were P-gp+ and the remaining 6 were P-gp-. Of the 18 with P-gp+ cancer, 11 relapsed and 9 died from tumor-related causes, while the other 7 remain free from tumor recurrence; however, all with P-gp- cancer are alive without recurrence. These observations suggest a bias toward a shorter survival for patients with P-gp+ cancer because P-glycoprotein may be associated with chemoresistance. Thus, detection of the expression of P-glycoprotein will aid in planning appropriate adjuvant chemotherapy for patients with non-small cell lung cancer.

Proposal for reasonable mediastinal lymphadenectomy in bronchogenic carcinomas: role of subcarinal nodes in selective dissection

OBJECTIVE

The aims of this study were to reveal the characteristics of skipping N2 lung cancer and to develop a more reasonable approach for dissecting mediastinal lymph nodes.

METHODS

Of consecutive 956 patients who were operated on for primary lung cancer from 1986 through 1996, 760 (79.5%) had a diagnosis of non-small cell carcinoma and were subjected to complete resection of the tumor together with hilar and mediastinal lymphadenectomy.

RESULTS

Of 141 patients with N2 disease, 53 (37.6%) had skipping metastases. Among 78 patients with N2 cancer of the upper lobe, 37 (47.4%) had skipping metastases affecting upper or aortic mediastinal nodes whereas none of them had skipping metastases affecting lower mediastinal nodes. Among 47 patients with N2 cancer of the lower lobe, 13 (27.7%) had skipping metastases affecting mediastinal nodes. Of these 13 patients, 11 (84.6%) had skipping metastases affecting the subcarinal node. The remaining 2 patients had a huge primary tumor.

CONCLUSIONS

Dissection of the upper part of the mediastinum including the aortic regions should be performed regardless of the operative appearance when cancer is located in the upper lobe, but it is not required for lower lobe tumors with negative hilar and subcarinal nodes. Dissection of the subcarinal node in patients with an upper lobe tumor is not routinely needed when the nodes in both the hilum and upper mediastinum are intact. We consider that the subcarinal node is of significance and skipping metastases should be defined as metastases that skip the subcarinal node in addition to N1 nodes.

Ongoing prospective study of segmentectomy for small lung tumors. Study Group of Extended Segmentectomy for Small Lung Tumor

BACKGROUND

Lesser resection for small lung tumors remains an unresolved problem. This study was conducted to see whether this type of operation is acceptable or not.

METHODS

From 1992 to 1994, 55 patients were enrolled in a multicenter trial of limited surgical resection for peripheral tumors of less than 2 cm diameter. The procedure consisted of segmentectomy with exploration of lymph nodes by examining frozen sections. The operation was modified if the report was positive. The intersegmental plane was identified by keeping the resected segments inflated and the preserved segments collapsed. To divide the plane, stapling or electrocauterization on the edge of the collapsed area was used. In this way the resection line was delivered beyond the burdened segment; this was called extended segmentectomy.

RESULTS

There were no perioperative deaths, but there were eight postoperative deaths. In 1 patient who died because of local recurrence, it had been known that the margin to the lesion had been narrow (15 mm); 1 had bilateral intrapulmonary nodules, 1 had nodules in the side that was not operated on, and another succumbed to a second neoplasm of small cell lung cancer 4 years after the first operation. The remaining 4 died of nonpulmonary diseases. Almost all other patients are alive and free from recurrence, except for 1 in whom N2 disease was not detected intraoperatively but was confirmed after the operation.

CONCLUSIONS

The interim results suggest that extended segmentectomy is applicable in patients with a small peripheral lung cancer. However, a wide margin and aggressive intraoperative pathologic examinations are mandatory.