| | Evaluation of extratumoral lymphatic permeation in non-small cell lung cancer as a means of predicting outcomeReceived 10 March 2006; received in revised form 2 August 2006; accepted 25 September 2006. Summary BackgroundLymphatic permeation (ly) has been described as a potential prognostic factor for non-small cell lung cancer (NSCLC). ConclusionsThese results indicate that ly status is a good prognostic marker of poorer outcome in patients with resected NSCLC. Non-small cell lung cancer (NSCLC) is one of the most prevalent and lethal cancers throughout the world. Many reports on clinicopathological prognostic factors in surgically treated NSCLC have been reviewed and the prognostic factors have included the serum carcinoembryonic antigen (CEA) value, the clinical N status, the extent of resection, the histological type of the primary tumor (adenocarcinoma), number of metastatic mediastinal lymph node stations, vascular involvement, lymphatic permeation and pleural invasion [1], [2], [3]. Many articles have reviewed and pointed out the importance of blood vessel invasion [4], [5], [6], [7] and lymphatic permeation [1], [2], [3]. Vascular or pleural invasion is much easier to evaluate as part of a routine pathological examination of lung cancer specimens than lymphatic permeation, because vascular walls and pleural elastic fibers can be confirmed by staining for elastic fibers. Since lymphatic vessels do not contain elastic fibers, however, they cannot be visualized by this method. No clear consensus regarding the optimal method for evaluating lymphatic permeation in NSCLC specimens has been reached and the correlation between lymphatic permeation and outcome remains a matter of controversy. The number of lymphatics in breast cancer [8], [9] and cancer of the head and neck region [10], [11] specimens has been found to be a prognostic factor and several reports on lymphatic permeation in patients with NSCLC have been reviewed [3], [12], [13], [14]. However, accurate evaluation according to the number of lymphatics is generally difficult, because artifactual spaces around cancer nests are often difficult to distinguish from lymphatic vessels containing tumor emboli, especially in intratumoral areas. To establish the optimal method for evaluating ly in NSCLC, we investigated whether the qualitative evaluation of ly according to its location provides an appropriate means of predicting the outcome of NSCLC. 1. Materials and methods  Between August 1, 2001 and December 31, 2003, primary resection for NSCLC was performed in 558 patients at the National Cancer Center Hospital East. Table 1 shows the characteristics of the 558 patients. The patients who received preoperative chemotherapy or preoperative thoracic radiation were excluded. The preoperative evaluation included a physical examination, bronchofiberscopy, chest radiography, computed tomographic scan of the chest and abdomen, MRI of the brain and isotopic bone scan. A primary resection was performed in all 558 patients. Limited resections (wedge resection or segmentectomy) was performed in 44 patients and the standard surgery for NSCLC, lobectomy or pneumonectomy with mediastinal lymphadenectomy, was performed in the other 514 patients. The available pathology slides from all 558 surgical specimens were reviewed in this study. The cancer has been staged according to the new 1997 international TNM criteria. The surgical specimens had been immediately fixed in 10% formalin and a routine histopathological workup with paraffin embedding was performed. Sections (4-μm thick) had been cut and stained with hematoxylin and eosin (HE) and Victoria blue van Gieson (VVG) [15], [16] and examined by light microscope. Conventional clinicopathological features were noted and recorded according to the World Health Organization's criteria. Lymphatic permeation was concluded present when tumor cells floating in lymphatic vessels with no supporting smooth muscles or elastic fibers were identified [6], [7]. We confirmed that lumens within the bronchovascular bundle, subpleural and intralobular pleural space were lymphatic vessels by immunostaining with anti-D2-40 antibody (Fig. 1A and B). Since artifactual spaces around cancer nests were often indistinguishable from lymphatic vessels containing tumor emboli, when tumor cells floating were identified in lumens within the bronchovascular bundle, subpleural, or interlobular pleural spaces, lymphatic permeation was concluded to be present. When we were not confident that the findings represented lymphatic permeation, we did not record the case as positive. Since August 1, 2001, we have recorded the location of lymphatic permeation according to our histologic criteria. The presence or absence of lymphatic permeation and its recorded location was as follows (Table 2): ly 0, absence of lymphatic permeation; ly 1, presence of intratumoral lymphatic permeation (Fig. 2A) and ly 2, presence of extratumoral lymphatic permeation (Fig. 2B). 3. Results The 4-year RFS rate of all 558 patients was 73.9%. Fig. 3A shows the RFS curves according to the results of the examination for lymphatic permeation (ly 0 versus ly 1 versus ly 2). The 4-year RFS rate of the ly 0 group (N =464), ly 1 group (N=42) and ly 2 group (N=52) was 73.9, 63.9 and 26.2%, respectively. The RFS time of the ly 2 group was significantly shorter than that of the ly 0 group (P<0.0001) and the ly 1 group (P=0.0028) and the difference between the ly 0 group and the ly 1 group (P=0.0225) was also significant. Fig. 3B shows the RFS curves according to lymphatic permeation (ly 0 versus ly 1, 2). The 4-year RFS rate of the patients with ly 1 plus ly 2 group (N=94) was 42.8%. The difference between the ly 0 group and the ly 1 plus ly 2 group was statistically significant (P<0.0001). We also analyzed the results of the pathological stage I patients alone. The 4-year RFS rate of the ly 2 group (N=9) and the ly 0 plus ly 1 group (N=369) was 33.3 and 85.6%, respectively. The RFS time of the 9 ly 2 patients was significantly shorter than that of the ly 0 plus ly 1 group (P<0.0001, data not shown). Six of the 9 ly 2 patients developed a distant metastasis within 1 year. Table 3 shows the results of the univariate analysis for each conventional clinicopathological factor of NSCLC. All variables, sex (male versus female), age (<65 versus ≤65), smoking status (smoker versus non-smoker), preoperative CEA value (<5 versus ≤5), histological type (adenocarcinoma versus others), pathological T status (pT1 versus pT2–4), pathological N status (pN0 versus pN1-2), vascular invasion (negative versus positive), lymphatic permeation (negative versus positive), extratumoral lymphatic permeation (negative versus positive), pleural invasion (negative versus positive) and pulmonary metastasis (negative versus positive) were correlated with the RFS time according to a Kaplan–Meier analysis. | a Log-rank test. bConsidered to be statistically significant (P<0.05). |
We tested for a correlation between lymphatic permeation and clinicopathological variables by means of the Pearson chi-square test and found a positive correlation with each of the following clinicopathological factors: sex, smoking status, CEA value, histological typing, pathological T status, pathological N status, vascular invasion, pleural invasion and pulmonary metastasis (data not shown). To determine whether the location of the lymphatic permeation had a stronger impact than any of the other clinicopathological factors on outcome, a multivariate analysis was performed by using the Cox proportional hazards regression model. All variables were included in the multivariate analysis, including whether lymphatic permeation was absent or present and the location of the lymphatic permeation (ly 0, 1 versus ly 2), if present. As shown in Table 4, the results showed that the location of the lymphatic permeation (ly 0, 1 versus ly 2) was an independent prognostic factor (P=0.0116), but whether lymphatic permeation present or not was not (P=0.5325). | a Considered to be statistically significant (P<0.05). |
4. Discussion This study focused on the histological evaluation of lymphatic permeation in resected material from patients with NSCLC to determine the prognostic value of this parameter. The results showed a significant difference between the RFS curve of the ly 2 group and the other two groups, the ly 0 group and the ly 1 group and ly 2 was significantly correlated with a poorer outcome. Grading according to the location of lymphatic permeation has not been previously reported for NSCLC. The multivariate analysis showed that the location of lymphatic permeation was a significant independent prognostic factor for recurrence, but that the conventional evaluation criterion was not negative (ly 0) versus positive (ly 1, 2). A statistically significant difference in RFS time was also observed between the ly 0 group and the ly 1 group and between the ly 1 group and the ly 2 group. These findings indicate that intratumoral lymphatic permeation is also correlated with a poor outcome. Although Timothy et al. found that intratumoral lymphatic vessels were not functional in an animal model [17], we propose that intratumoral lymphatics are functional in NSCLC patients. When the series was limited to pathological stage I patients, a significant difference was observed between the 9 ly 2 patients and the 369 ly 0 plus ly 1 patients; six of the 9 ly 2 patients developed a distant metastasis within 1 year of surgery, suggesting that patients with extratumoral lymphatic permeation tend to have a poor prognosis, even pathological stage I patients. We think that extratumoral lymphatic permeation is an early phase of carcinomatous lymphangiosis and adjuvant treatment might be necessary for such patients. In conclusion, this study clearly demonstrated the prognostic value of extratumoral lymphatic permeation in NSCLC. Evaluation of the location of lymphatic permeation should be included in routine histopathologic diagnosis because of the prognostic value of this parameter and its excellent objectivity and reproducibility. Acknowledgements The authors thank Professor J.P. Barron of the International Medical Communications Centre of Tokyo Medical University for reviewing this manuscript. The work was supported in part by a Grant-in-Aid for Cancer Research from the Ministry of Health, Labour and Welfare of Japan. References [1]. [1]Suzuki K, Nagai K, Yoshida J, Nishimura M, Takahashi K, Yokose T, et al. Conventional clinicopathologic prognostic factors in surgically resected nonsmall cell lung carcinoma. Cancer. 1999;86:1976–1984. [2]. [2]Poleri C, Morero JL, Nieva B, Vazquez MF, Rodgriguez C, de Titto E, et al. Risk of recurrence in patients with surgically resected stage I non-small cell lung carcinoma. Chest. 2003;123:1858–1867. MEDLINE |
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a Division of Thoracic Oncology, National Cancer Center Hospital East, 6-5-1 Kashiwanoha, Kashiwa, Chiba, Japan b Pathology Division, Research Center for Innovative Oncology, National Cancer Center Hospital East, Kashiwa, Chiba, Japan  Corresponding author at: Division of Thoracic Oncology, National Cancer Center Hospital East, 6-5-1 Kashiwanoha, Kashiwa, Chiba 277-8577, Japan. Tel.: +81 471 33 1111; fax: +81 471 31 4724.
PII: S0169-5002(06)00526-5 doi:10.1016/j.lungcan.2006.09.027 © 2006 Elsevier Ireland Ltd. All rights reserved. | |
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