Favorable and unfavorable morphological prognostic factors in peripheral adenocarcinoma of the lung 3 cm or less in diameter

Evolving Concepts in the Pathology and Computed Tomography Imaging of Lung Adenocarcinoma and Bronchioloalveolar Carcinoma

Purpose

To review recent advances in pathology and computed tomography (CT) of lung adenocarcinoma and bronchioloalveolar carcinoma (BAC).

Methods

A pathology/CT review panel of pathologists and radiologists met during a November 2004 International Association for the Study of Lung Cancer/American Society of Clinical Oncology consensus workshop in New York. The purpose was to determine if existing data was sufficient to propose modification of criteria for adenocarcinoma and BAC as newly published in the 2004 WHO Classification of Lung Tumors, and to address the pathologic/radiologic concept of diffuse/multicentric BAC.

Results

Solitary small, peripheral BACs have an excellent prognosis. Most lung adenocarcinomas with a BAC pattern are not pure BAC, but rather adenocarcinoma, mixed subtype with invasive patterns. This applies to tumors presenting with a diffuse/multinodular as well as solitary nodule pattern. The percent of BAC versus invasive components in lung adenocarcinomas appears to be prognostically important. However, a consensus definition of “minimally invasive” BAC with a favorable prognosis could not be achieved. While recognition of a BAC component is possible, the diagnosis of BAC with exclusion of invasive adenocarcinoma cannot be made by small biopsy or cytology specimens.

Conclusion

There is a need to work toward a mutual understanding and consensus between pathologists, clinicians, and researchers with the use of the term BAC versus adenocarcinoma. Future studies should make some attempt to quantitate these components and/or other features such as size of scar, size of invasive component, or pattern of invasion. Hopefully, this work will allow definition of a category of adenocarcinoma, mixed subtype with predominant BAC/minimal invasion and a favorable prognosis.

Current status of small peripheral adenocarcinomas of the lung and their importance to pathologists

There has been a large amount of work done recently on small peripheral stage I adenocarcinomas that come to resection. Radiological (including proportion of ground glass opacity) and pathological features of these lesions (predominant bronchioloalveolar component, central scar with or without invasion <0.5 cm) have been shown to be prognostically favorable with cure rate approaching 100% in some series. Most of these studies emanate from Japan. The relevance of these studies to other parts of the world, particularly North America, is discussed in light of the fact that some recent chemotherapeutic studies with gefitinib have shown increased response in individuals of Asian origin, suggesting that some genetic differences may be significant. The relevance of these findings to pathologists and the pathological study of small peripheral adenocarcinomas from elsewhere in the world are discussed.

Surgically Curable Peripheral Lung Carcinoma

STUDY OBJECTIVES

To define characteristics of surgically curable, early cancers of the lung, we retrospectively studied relationships between thin-section CT (TS-CT) scans, pathologic features, and outcome data in 287 patients with resected small-diameter (< 20 mm) peripheral lung carcinoma. Cases included 260 adenocarcinomas, 16 squamous cell carcinomas, 6 small cell carcinomas, 3 large cell carcinomas, and 2 others.

MEASUREMENTS AND RESULTS

All tumors were classified by tumor shadow disappearance rate (TDR) on TS-CT as having either an "air-containing" or "solid-density" pattern. Adenocarcinomas are typically classified into these patterns. Air-containing patterns (n = 136) showed 1% pleural involvement and 2% vascular invasion, with no lymphatic permeation by pathology. Solid-density patterns (n = 124) showed 34% pleural involvement, 42% vascular invasion, and 29% lymphatic permeation. No cases of relapse or death were observed in cases with the air-containing pattern, in contrast to the high relapse and death rate in solid-density cases (p < 0.0001). All non-adenocarcinoma cases (n = 25) had a solid-density pattern, with 4% pleural involvement, 52% vascular invasion, and 44% lymphatic permeation. The overall 5-year survival rate for non-adenocarcinoma was 60%, similar to that for solid-density adenocarcinoma.

CONCLUSIONS

When peripheral lung cancers < 20 mm in diameter show air-containing patterns on TS-CT images, surgical outcomes may be favorable with curable disease.

Growth pattern correlates with the distribution of basement membrane and prognosis in lung adenocarcinoma

Lung adenocarcinoma frequently has a histologic heterogeneity, particularly with regard to its cell morphology and growth pattern, with or without stromal desmoplasia. However, little is known about the relationship between morphologic heterogeneity and the destruction of BM. We selected 147 foci showing different growth patterns studied in 76 patients with lung adenocarcinoma and examined immunohistochemically the distribution of BM antigens, as well as the expression of MMPs and TIMP-2. BM antigens were more highly preserved in foci of the BAC growth pattern (94.7%) than in those of the papillary/acinar (24.5%) and solid patterns (16.1%) (p<0.01). MMP-2-positive cancer cells were significantly more frequent in poorly preserved foci of BM antigens than in preserved foci (p<0.05). The population of TIMP-2-positive cancer cells showed a positive correlation with BM preservation (p<0.05). However, no significant relationship between growth pattern and expression of MMP-9 and -14 was found. BM antigens had almost totally disappeared in desmoplastic foci. Multivariate analyses revealed that pathologic stage and high expression of TIMP-2 were independent prognostic factors. These findings indicate that the histologic heterogeneity of lung adenocarcinomas is partly related to the cancer cell-stromal interaction, in particular through BM preservation or destruction, which was mainly affected by cancer cell expression of MMP-2 and TIMP-2 in lung adenocarcinomas.

Bronchioloalveolar carcinoma of the lung 3 centimeters or less in diameter: a prognostic assessment

BACKGROUND

Bronchioloalveolar carcinoma (BAC) of the lung is a subtype of adenocarcinoma for which the incidence is actually rising, but the histologic definition of BAC has been recently changed by the revised World Health Organization (WHO) classification in 1999. The clinical features of patients with BAC diagnosed according to the recently revised WHO classification have not yet been clarified. In this retrospective study, we investigated the pattern of recurrence and survival outcome for patients with resected BAC by pathology review, compared with those in patients who had adenocarcinoma other than BAC.

METHODS

From 1985 through 2002, 108 patients underwent surgical resection for pulmonary adenocarcinoma 3 cm or less in diameter at the University of Yamanashi, Japan. All of the resected specimens of these 108 patients were pathologically reviewed again to confirm the diagnosis as BAC or adenocarcinoma other than BAC. The tumor was defined as BAC when the adenocarcinoma lesion had a pure bronchioloalveolar growth pattern and no evidence of stromal, vascular, or pleural invasion according to the WHO classification (third edition).

RESULTS

Twenty-five patients (23%) had a diagnosis of BAC, and 83 (77%) had a diagnosis of other adenocarcinoma. There was a female predominance among both patients with BAC and those with other adenocarcinoma. Lymph node involvement was seen for 30 lesions (36%) of adenocarcinoma other than BAC, but not for any BAC lesions. The median duration of follow-up after surgery was 5.1 years. There was no recurrence in the postoperative course in patients with BAC for a 5-year disease-free survival rate of 100%, whereas the 5-year disease-free survival rate for other adenocarcinoma was 63.5%.

CONCLUSIONS

The patients with resected BAC, which is defined as a noninvasive adenocarcinoma by the revised WHO classification, had an excellent prognosis. However, these results may depend on a strictly accurate pathology diagnosis as BAC. Limited resection might be curative in patients with focal BAC based on evidence of pathologic noninvasive features.

A Three-dimensional Analysis of Blood Vessels in Bronchioloalveolar Carcinoma

The three-dimensional architecture of blood vessels within lung adenocarcinomas has not been well studied. In 19 cases with bronchioloalveolar carcinoma with central fibrosis, we three-dimensionally examined blood vessel architecture in 150 microm thick sections stained with elastin staining and anti-CD34 antibody. We examined four regions: normal alveoli and three regions within the tumor including an area adjacent to the normal alveoli (external area), an area in which tumor cells were replacing epithelial cells (replacement area), and a central fibrotic area (fibrotic area). Elastin staining showed that elastic fibers formed the framework of the alveoli, and the alveolar structure shrank more strongly to the center of the tumor due to folding of alveolar walls invaded by adenocarcinoma cells. We also measured three vessel parameters in these four regions. The vessel diameters were 4.08+/-1.10 microm, 3.95+/-1.02 microm, 5.04+/-1.56 microm, and 6.11+/-2.23 microm, the circumferences of those vessels seen as complete circles were 43.11+/-12.78 microm, 43.71+/-12.87 microm, 95.21+/-39.32 microm, and 126.77+/-54.65 microm; the lengths between vessel bifurcations were 13.28+/-3.08 microm, 13.47+/-4.58 microm, 24.91+/-9.66 microm, and 41.82+/-28.08 microm in the normal alveoli, and the external, replacement, and fibrotic areas, respectively. Blood vessel architecture changed such that the vessels became larger and coarser towards the center of the tumor. Our three-dimensional analysis suggests continuous remodeling of alveolar capillaries rather than angiogenesis within bronchioloalveolar carcinoma.

Allelic losses on chromosome 3p are accumulated in relation to morphological changes of lung adenocarcinoma

We performed allelotyping analysis at nine regions on chromosome 3p using 56 microdissected samples from 23 primary lung adenocarcinomas to examine the process of progression within individual lung adenocarcinoma with various grades of differentiation. Identical allelic patterns among various grades of differentiation were found in eight cases. Accumulation of allelic losses from high to lower differentiated portions was found in seven cases and accumulation of allelic losses from low to higher differentiated portions was found in five cases. Various allelic patterns among various grades of differentiation were found in three cases. These results suggested that allelic losses on 3p play an important role in morphological changes of lung adenocarcinomas. We also investigated the relationship between allelic losses on 3p and histological subtypes of lung adenocarcinoma. The frequencies of allelic losses at 3p14.2 and telomeric region of 3p21.3 were higher in papillary type tumour (nine out of 14, 64% and 11 out of 15, 73%) than in bronchioloalveolar carcinoma-type tumour (one out of 8, 13%; P=0.031 and four out of 12, 33%; P = 0.057). These results indicated that allelic losses at 3p14.2 and telomeric region of 3p21.3 are related to pattern of the proliferation of lung adenocarcinoma.

Cytologic factors associated with prognosis in patients with peripheral adenocarcinoma of the lung measuring 3 cm or less in greatest dimension

BACKGROUND

Recently, peripheral lung adenocarcinomas (PLA) measuring < or = 3 cm in greatest dimension often have been diagnosed using diagnostic radiology. The objective of the current study was to determine which cytologic factors are associated with a favorable outcome and an unfavorable outcome in patients with PLA.

METHODS

Imprint smears from 134 patients with PLA were examined. Sixteen cytologic factors, including necrosis, cellular distribution, overlapping of cell clusters, cluster aggregation, cluster size, cluster thickness, nuclear irregularity, nuclear size, variation in nuclear size, multinucleated cells, intranuclear inclusions, type of intranuclear inclusions, appearance of nucleoli, eosinophilic nucleoli, multinucleoli, and mitosis, were evaluated using univariate and multivariate analyses. A counting method was used to determine the prognosis for individual patients.

RESULTS

In the univariate analysis, a cluster size that measured > or = 831 microm in short dimension (P = 0.0011), moderate or severe nuclear irregularity (P = 0.0030), > or = 5 multinucleated cells per 100 tumor cells (P = 0.0047), moderate or severe variation in nuclear size (P = 0.0061), medium or large nuclear size (P = 0.0169), and > or = 1 mitotic cell per 100 tumor cells (P = 0.0412) were associated significantly with a poor outcome. In the multivariate analysis, cluster size in short dimension (P = 0.0018), multinucleated cells (P = 0.0066), and nuclear irregularity (P = 0.0310) were found to be independent prognostic factors.

CONCLUSIONS

The combination of cytologic features using intraoperative imprint smears, namely, cluster sizes < or = 830 microm in short dimension, < or = 4 multinucleated cells per 100 tumor cells, and mild nuclear irregularity, may provide favorable predictive information in patients with PLA.

Grade of Stromal Invasion in Small Adenocarcinoma of the Lung

The pathologic features of invasion such as stromal disruption and pleural/vascular involvement have been shown to be of prognostic value in adenocarcinoma. However, the relationship between the degree of invasion, histologic subtype of adenocarcinoma, and prognosis remains unclear. We retrospectively studied 380 peripheral adenocarcinomas of < or = 2.0 cm in diameter with regard to histology and clinical profiles. Their degree of invasive growth was classified into four grades as follows according to the structural deformity and its location in the adenocarcinoma lesion: Grade 0 had a pure bronchioloalveolar growth pattern and no evidence of stromal invasion. Grade 1 had stromal invasion in the area of bronchioloalveolar growth. Grade 2 had stromal invasion localized on the periphery of a fibrotic focus. Grade 3 had stromal invasion into the center of a fibrotic focus. The clinicopathological data were obtained from medical records. The distribution of the histologic grade of invasion was as follows: grade 0 in 85 tumors (22%), grade 1 in 37 (10%), grade 2 in 46 (12%), and grade 3 in 212 (56%). This histologic grade of invasion was closely related to other indicators of tumor spread. Vascular/lymphatic permeation was seen in none of grade 0, in 1 lesion each of grade 1 and grade 2, and 144 (68%) of grade 3. Lymph node metastasis was seen in 57 (27%) lesions of grade 3 but not in grades 0, 1, or 2. The 5-year disease-free survival rates were 100%, 100%, 100%, and 59.6% for tumors with grade 0, grade 1, grade 2, and grade 3 invasion, respectively. Tumors with grade 1 and grade 2 invasion, like tumors with grade 0 invasion (bronchioloalveolar carcinoma), showed an excellent prognosis. Therefore, tumors with grade 1 and grade 2 invasion could be considered "minimally invasive" or "early" adenocarcinomas.

Expression of the TSLC1 adhesion molecule in pulmonary epithelium and its down-regulation in pulmonary adenocarcinoma other than bronchioloalveolar carcinoma

TSLC1 (tumor suppressor in lung cancer-1) is an adhesion molecule of the Ig superfamily that binds homophilically and mediates cell-cell interactions. Originally, TSLC1 was cloned as a candidate tumor suppressor from the genomic region that frequently exhibits loss of heterogeneity in human non-small-cell lung cancer (NSCLC). However, there have been no studies on TSLC1 expression in normal lungs or NSCLC. Here we show that pulmonary epithelial cells express TSLC1 and its expression levels are often decreased or lost in primary pulmonary adenocarcinoma, a major histologic type of NSCLC. Immunohistochemistry revealed that TSLC1 was localized at cell-cell boundaries of all columnar epithelial cells in mouse embryonic lungs of 10.5 and 13 days postcoitus. Similar staining patterns were observed in bronchiolar and alveolar epithelial cells of adult human lungs, suggesting a physiologic role for TSLC1 in interactions of these cells. Next we performed Western blot analyses of TSLC1 in 47 primary pulmonary adenocarcinomas and judged each tumor as either decreased or nondecreased by comparing TSLC1 expression levels of the tumor with the levels of normal lungs. The expression profiles had a significant relation to histologic subtypes but not to other clinicopathologic parameters. Sixteen bronchioloalveolar carcinomas (BACs) were all judged nondecreased, while 19 of 31 (63%) adenocarcinomas other than BAC were judged decreased (p < 0.0001). Immunohistochemistry of tumors judged nondecreased revealed that not only BAC cells but also tumor cells in lepidic growth components of adenocarcinomas other than BAC expressed TSLC1 on their lateral plasma membranes. These tumor cells are considered less invasive because they proliferate in a lepidic growth pattern along alveolar walls. Thus, the present results not only support the hypothesis that TSLC1 is a tumor suppressor of NSCLC but also suggest that preserved integrity of TSLC1 may contribute to less invasive phenotypes of lepidic growth tumor cells.

Lung adenocarcinoma with mixed bronchioloalveolar and invasive components: clinicopathological features, subclassification by extent of invasive foci, and immunohistochemical characterization

A significant proportion of small lung adenocarcinomas consists of two components: bronchioloalveolar carcinoma (BAC) and invasive carcinoma. The purpose of this study was to compare their clinicopathologic features with those of BAC and those of invasive cancer without BAC, and to define "early invasive" lesions based on the extent of invasive foci. We reviewed 484 lesions of resected lung adenocarcinoma and classified them into three groups according to tumor growth pattern: group 1 (n = 102, BAC), group 2 (n = 216, adenocarcinoma consisting of BAC and invasive carcinoma), and group 3 (n = 166, invasive adenocarcinoma without BAC component). Group 2 was further subdivided according to the extent of the invasive area: group 2a (n = 54), BAC with invasive foci 5 mm. These groups were compared with regard to their clinicopathologic features, expression of Ki-67 and p53, and expression of laminin-5, a putative marker for tumor invasion. The positivity rates of vascular, lymphatic, and pleural invasion in each group were as follows: 0%, 0%, and 0% in group 1; 5.5%, 14.8%, and 1.9% in group 2a; 45.7%, 41.4%, and 25.9% in group 2b; and 84.9%, 61.4%, and 60.8% in group 3. Notably, no lymph node metastasis occurred in either group 2a or group 1, but it was observed in 24.1% of group 2b and 47.0% of group 3. The mean Ki-67 labeling index, the frequency of p53 overexpression, and the frequency of laminin-5 overexpression increased from group 1 (11%, 4%, and 0%) to group 2a (16%, 20%, and 7%) to group 2b (24%, 41%, and 23%) to group 3 (35%, 38%, and 38%). In contrast, no clear differences were observed when lesions were subdivided according to size. Based on the distribution pattern of Ki-67-positive tumor cells, lesions were classified into two groups: marginal type (63%) and nonmarginal type (37%). The latter showed a significantly higher labeling index than the former. Moreover, the proportion of the marginal type clearly decreased from group 1 (85%) and group 2a (87%) to group 2b (55%) to group 3 (19%). Group 2 lesions showed characteristics intermediate between the BAC and invasive adenocarcinoma. According to the extent of the invasive area, we were able to define a subgroup of mixed-type adenocarcinomas (group 2a) that could be regarded as early invasive cancer because they showed low rates of vascular, lymphatic, and pleural invasion, and no nodal involvement.

Clinicopathologic characteristics of peripheral squamous cell carcinoma of the lung

Squamous cell carcinoma of the lung can be divided into two types according to the location of the primary site: the central type and the peripheral type. The clinicopathologic factors in the peripheral type of lung squamous cell carcinoma have not yet been fully evaluated. A total of 204 surgically resected lung squamous cell carcinomas were reviewed with special reference to their location, histologic characteristics based on tumor growth patterns, and clinicopathologic factors. The central type and the peripheral type accounted for 95 and 109 cases, respectively. Although the patient population of the peripheral type was older, with a lower pathologic stage, lower lymphatic vessel involvement, and lymph node metastasis, the Kaplan-Meier survival proportions did not differ significantly between these two groups. Based on the histologic growth pattern, the peripheral type was classified under three subgroups as follows: 1). the alveolar space-filling type, 2). the expanding type, and 3). the combined type. Among these three types, the alveolar space-filling type showed neither lymphatic vessel invasion nor lymph node metastasis and had the most favorable prognosis. The central and peripheral types of lung squamous cell carcinoma have different clinicopathologic characteristics and should be classified under respectively different categories.

Frequent overexpression of the c-kit protein in large cell neuroendocrine carcinoma of the lung

Overexpression of receptor-type tyrosine kinases in various cancers is associated with an aggressive tumor phenotype and poor outcome, but their expression had never been evaluated in large cell neuroendocrine carcinoma (LCNEC) of the lung. In the present study, we investigated the expression of three receptor tyrosine kinases, epidermal growth factor receptor (EGFR), c-erbB-2, and c-kit protein, by comparing surgically resected 40 LCNECs with other neuroendocrine (NE) lung tumors: 9 typical carcinoids (TCs), 5 atypical carcinoids (ACs), and 13 small cell lung carcinomas (SCLCs). None of the NE lung tumors showed expression of EFGR or c-erbB-2, but c-kit was overexpressed in 55% of the LCNEC tumor cells and 46% of the SCLC tumor cells. None of the clinicopathologic factors in either the LCNEC or SCLC patients correlated with c-kit overexpression. The finding that c-kit expression in LCNEC is similar to its expression in SCLC suggests that inhibition of c-kit may be effective as a therapy targeting LCNEC as well as SCLC.

Modified scar grade: a prognostic indicator in small peripheral lung adenocarcinoma

BACKGROUND

Several studies have shown the prognostic value of desmoplasia for lung adenocarcinomas. The authors evaluated the density and extent of desmoplasia by modifying the scar grade, as well as the prognostic impact on patient survival.

METHODS

Modified scar grade was defined as follows: Grade 1, no desmoplasia; Grade 2, sparse desmoplastic reaction; Grade 3, dense desmoplastic reaction with diameter of 10 mm or less; Grade 4, dense desmoplastic reaction with diameter exceeding 10 mm. In addition, the prognostic impact of conventional histologic factors and modified scar grade was analyzed in 239 cases of small peripheral lung adenocarcinoma (maximum dimension, </= 30 mm) for which long-term follow-up data were available.

RESULTS

The 5 and 10-year survival rates according to the modified scar grade were 100% and 100% for Grade 1 lung adenocarcinoma (n = 29); 91.7% and 83.7% for Grade 2 (n = 61); 67.6% and 52.7% for Grade 3 (n = 78); and 50.0% and 37.5% for Grade 4 (n = 71), respectively. A significant difference in patient survival was found between Grade 1 or 2 versus Grade 3 or 4 (P < 0.0001, by log rank test). Multivariate analysis showed that modified scar grade was an independent prognostic factor (P = 0.0176), as were pathologic stage (P = 0.0293), lymph node metastasis (P = 0.0191), lymphatic permeation (P = 0.0022), and pleural involvement (P = 0.0452). Modified scar grade also had a significant impact on survival in various subsets of patients, including those with pathologic Stage IA disease, patients with tumors of diameter 20 mm or less, or patients with mixed subtype tumors with a bronchioloalveolar component.

CONCLUSIONS

Modified scar grade is a useful prognostic factor in patients with small lung adenocarcinomas. Tumors with a sparse fibroblastic reaction (modified scar Grade 2) may represent early invasive cancers or invasive cancers with low malignant potential, which should be distinguished from frankly invasive cancers (modified scar Grade 3 or 4).

Computed tomographic image comparison between mediastinal and lung windows provides possible prognostic information in patients with small peripheral lung adenocarcinoma

OBJECTIVES

The purpose of this study was to determine whether the ratio of the area of the mediastinal computed tomographic image to that of the lung computed tomographic image can be a prognostic factor of small peripheral lung adenocarcinoma.

METHODS

We studied the computed tomographic images of 143 patients with primary peripheral lung adenocarcinoma of 30 mm or less in maximum diameter. Two groups were categorized according to the tumor's ratio of the area of the mediastinal computed tomographic image to that of the lung computed tomographic image (tumor's area in the mediastinal computed tomographic image/tumor's area in lung computed tomographic image x 100%), both faint density-type (<50%) and solid-type images (>/=50%). Clinical factors and prognoses of the 2 groups were analyzed.

RESULTS

There were 58 patients with the solid-type tumor image and 85 patients with the faint density-type tumor image. The number of patients with tumor size of less than 20 mm in the faint density-type tumor group (n = 30) was significantly higher than that in the solid-type tumor group (n = 8, P =.008). The 5-year survival of patients with faint density-type tumors was 74.1%, whereas that in patients with solid-type tumors was 54.2% (P =.013). Furthermore, the survival curve of patients with the solid-type computed tomographic image combined with ground-glass opacity was similar to that of patients with the faint density-type image. Multivariate analysis revealed the prognostic influence of the ratio of the area of the mediastinal computed tomographic image to that of the lung computed tomographic image on survival (P =.029, relative risk = 0.48) and showed to be of second highest influence after the N factor.

CONCLUSIONS

It is suggested that the ratio of the area of the mediastinal computed tomographic image to that of the lung computed tomographic image can be a prognostic factor in patients with small peripheral lung adenocarcinoma.

The significance of E-cadherin and alpha-, beta-, and gamma-catenin expression in surgically treated non-small cell lung cancers of 3 cm or less in size

OBJECTIVES

Expression of the cell-cell adhesion molecules E-cadherin and alpha-, beta-, and gamma-catenin seems closely related to tumor invasiveness. The relationship between the expression and clinicopathologic characteristics in surgically resected non-small cell lung cancers of 3 cm or less in size was studied. The relationship to patient survival was analyzed.

METHODS

A total of 115 patients with surgically resected lung cancers of 3 cm or less in size were enrolled in this study. Expression of E-cadherin and alpha-, beta-, and gamma-catenin was immunohistochemically measured. The chi(2) test was used to correlate this expression with clinicopathologic parameters. Their influence on patient survival was evaluated with the Cox proportional hazards model.

RESULTS

There was a positive correlation between E-cadherin and catenin expression in lung cancers. In general, E-cadherin and catenin expression were greater in tumors that were either bronchioloalveolar carcinomas or adenocarcinomas, well differentiated, early stage, peripheral, and without vascular or pleural invasion. By using multicovariate analysis of patient survival, only early-stage and peripheral tumors were significantly favorable prognostic factors. Further analysis of the group of patients with early-stage disease showed that higher alpha-, beta-, or gamma-catenin expression was a favorable prognostic indicator.

CONCLUSION

Expression of alpha-, beta-, or gamma-catenin can be used as a prognostic indicator in patients with surgically resected stage I non-small cell lung cancers of 3 cm or less in size.

Pathology of lung cancer

This article reviews current concepts in pathologic classification of lung cancer based on 1999 World Health Organization (WHO)/International Association for the Study of Lung Cancer (IASLC) classification. Preinvasive lesions including squamous dysplasia/carcinoma in situ, atypical adenomatous hyperplasia and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia are discussed in addition to current concepts of bronchioloalveolar carcinoma and neuroendocrine tumors.

Expression of matrix metalloproteinases in invasive pulmonary adenocarcinoma with bronchioloalveolar component and atypical adenomatous hyperplasia

To investigate the association between the expression of matrix metalloproteinases (MMPs) and their tissue inhibitors (TIMPs) and the clinicopathological features in lepidic and invasive components of adenocarcinoma of the lung, we performed immunostaining for type IV collagen, various MMPs, and TIMPs in 27 cases of invasive adenocarcinomas and 5 cases of atypical adenomatous hyperplasia of alveolar epithelial cells (AAH). Mean extent of lepidic growth was 61% and the survival was significantly better in cases with 50% or more lepidic component. The preservation of type IV collagen in lepidic areas correlated inversely with lymphatic or vascular invasion (P = 0.02 and 0.002, respectively). Five-year survival was reduced in cases showing destruction of type IV collagen (P = 0.004) or expression of MMP-2 (P = 0.008) in lepidic areas. MMP-2 co-localized with MT-1-MMP (its activating enzyme) and TIMP-2 in neoplastic cells. Reactivity for other MMPs and TIMPs did not correlate with destruction of type IV collagen or prognosis. Type IV collagen was preserved in all cases of AAH. MMP-2, but not MT-1-MMP, was expressed in two of the five cases of AAH. Immunostaining for type IV collagen MMP-2 is useful in evaluating the prognosis of the lung.