High prevalence of atypical adenomatous hyperplasia of the lung in autopsy specimens from elderly patients with malignant neoplasms

Prevalence of subclinical lung cancer detected at autopsy: a systematic review

BACKGROUND

Lung cancer screening in high-risk populations with low-dose computed tomography is supported by international associations and recommendations. Overdiagnosis is considered a risk of screening with associated harms. The aim of this paper is to determine the prevalence of subclinical lung cancer diagnosed post-mortem to better understand the reservoir of subclinical lung cancer.

METHODS

We searched EMBASE, PubMed, and MEDLINE databases from inception until March 2022 with no language restrictions. We considered all studies with ≥100 autopsies in adults. Two reviewers independently assessed eligibility of studies, extracted data, and assessed risk of bias of included studies. We performed a meta-analysis using a random-effects model for prevalence of subclinical lung cancer diagnosed post-mortem with sensitivity and subgroup analyses.

RESULTS

A total of 13 studies with 16 730 autopsies were included. Pooled prevalence was 0.4% (95% CI 0.20 to 0.82%, I2 = 84%, tau2 = 1.19, low certainty evidence,16 730 autopsies). We performed a sensitivity analysis excluding studies which did not specify exclusion of children in their cohort, with a pooled prevalence of subclinical lung cancer of 0.87% (95% CI 0.48 to 1.57%, I2 = 71%, tau2 = 0.38, 6998 autopsies, 8 studies).

CONCLUSIONS

This is the first published systematic review to evaluate the prevalence of post-mortem subclinical lung cancer. Compared to autopsy systematic reviews in breast, prostate and thyroid cancers, the pooled prevalence is lower in lung cancer for subclinical cancer. This result should be interpreted with caution due to the included studies risk of bias and heterogeneity, with further high-quality studies required in target screening populations.

Impact of risk factors on early cancer evolution

Recent identification of oncogenic cells within healthy tissues and the prevalence of indolent cancers found incidentally at autopsies reveal a greater complexity in tumor initiation than previously appreciated. The human body contains roughly 40 trillion cells of 200 different types that are organized within a complex three-dimensional matrix, necessitating exquisite mechanisms to restrain aberrant outgrowth of malignant cells that have the capacity to kill the host. Understanding how this defense is overcome to trigger tumorigenesis and why cancer is so extraordinarily rare at the cellular level is vital to future prevention therapies. In this review, we discuss how early initiated cells are protected from further tumorigenesis and the non-mutagenic pathways by which cancer risk factors promote tumor growth. By nature, the absence of permanent genomic alterations potentially renders these tumor-promoting mechanisms clinically targetable. Finally, we consider existing strategies for early cancer interception with perspectives on the next steps for molecular cancer prevention.

Glucocorticoid Clearance and Metabolite Profiling in an In Vitro Human Airway Epithelium Lung Model

The emergence of microphysiologic epithelial lung models using human cells in a physiologically relevant microenvironment has the potential to be a powerful tool for preclinical drug development and to improve predictive power regarding in vivo drug clearance. In this study, an in vitro model of the airway comprising human primary lung epithelial cells cultured in a microfluidic platform was used to establish a physiologic state and to observe metabolic changes as a function of glucocorticoid exposure. Evaluation of mucus production rate and barrier function, along with lung-specific markers, demonstrated that the lungs maintained a differentiated phenotype. Initial concentrations of 100 nM hydrocortisone (HC) and 30 nM cortisone (C) were used to evaluate drug clearance and metabolite production. Measurements made using ultra-high-performance liquid chromatography and high-mass-accuracy mass spectrometry indicated that HC metabolism resulted in the production of C and dihydrocortisone (diHC). When the airway model was exposed to C, diHC was identified; however, no conversion to HC was observed. Multicompartmental modeling was used to characterize the lung bioreactor data, and pharmacokinetic parameters, including elimination clearance and elimination half-life, were estimated. Polymerse chain reaction data confirmed overexpression of 11-β hydroxysteroid dehydrogenase 2 (11βHSD2) over 11βHSD1, which is biologically relevant to human lung. Faster metabolism was observed relative to a static model on elevated rates of C and diHC formation. Overall, our results demonstrate that this lung airway model has been successfully developed and could interact with other human tissues in vitro to better predict in vivo drug behavior.

Indeterminate pulmonary nodules: risk for having or for developing lung cancer?

This perspective discusses the report by Pinsky and colleagues, which addresses whether noncalcified pulmonary nodules identified on CT screening carry short- and long-term risk for lung cancer. We are facing challenges related to distinguishing a large majority of benign nodules from malignant ones and among those a majority of aggressive from indolent cancers. Key questions in determining individual probabilities of disease, given their history, findings on CT, and upcoming biomarkers of risk, remain most challenging. Reducing the false positives associated with current low-dose computed tomography practices and identification of individuals who need therapy and at what time during tumor surveillance could reduce costs and morbidities associated with unnecessary interventions.

Association of CYP19A1 polymorphisms with risks for atypical adenomatous hyperplasia and bronchioloalveolar carcinoma in the lungs

Estrogen has been indicated to play an etiological role in the development of lung adenocarcinoma (ADC), particularly bronchioloalveolar carcinoma (BAC), a type of ADC that develops from a benign adenomatous lesion, atypical adenomatous hyperplasia (AAH). Polymorphisms in the CYP19A1 gene cause interindividual differences in estrogen levels. Here, 13 CYP19A1 single-nucleotide polymorphisms (SNPs) were examined for associations with lung AAH risk. AAH is detected as ground-glass opacity (GGO) by computed tomography (CT) examination, and this study consisted of 100 individuals diagnosed with GGO in their lungs among 3088 CT-based cancer screening examinees and 424 without. Minor allele carriers for the rs3764221 SNP showed an elevated risk for GGO [odds ratio (OR) = 1.72, P = 0.017]. Associations of this SNP with risks for lung AAH and BAC in the lungs were next examined using 359 ADC cases whose resected lung lobes were subjected to a histological examination for AAH accompaniment and the presence of BAC components and 330 controls without cancer. The ORs were also increased for lung ADC accompanied by AAH (OR = 1.74, P = 0.029) as well as lung ADC with BAC components (OR = 1.41, P = 0.091). The minor allele was associated with an increased circulating estradiol level (P = 0.079) in a population of 363 postmenopausal women without cancer. These results indicate that CYP19A1 polymorphisms are involved in the risk for lung AAH and BAC in the lungs by causing differences in estrogen levels.

Clinical, pathological and thin-section CT features of persistent multiple ground-glass opacity nodules: comparison with solitary ground-glass opacity nodule

PURPOSE

To retrospectively compare the clinical, pathological, and thin-section CT features of persistent multiple ground-glass opacity (GGO) nodules with those of solitary GGO nodules.

MATERIALS AND METHODS

Histopathologic specimens were obtained from 193 GGO nodules in 136 patients (87 women, 49 men; mean age, 57; age range 33-81). The clinical data, pathologic findings, and thin-section CT features of multiple and solitary GGO nodules were compared by using t-test or Fisher's exact test.

RESULTS

Multiple GGO nodules (n=105) included atypical adenomatous hyperplasia (AAH) (n=31), bronchioloalveolar carcinoma (BAC) (n=33), adenocarcinoma (n=34) and focal interstitial fibrosis (n=7). Solitary GGO nodules included AAH (n=8), BAC (n=15), adenocarcinoma (n=55) and focal interstitial fibrosis (n=10). AAH (P=.001) and BAC (P=.029) were more frequent in multiple GGO nodules, whereas adenocarcinoma (P<.001) was more frequent in solitary GGO nodules. Female sex (P<.001), nonsmoker (P=.012) and multiple primary lung cancers (P<.001) were more frequent for multiple GGO nodules, which were smaller (12 mm+/-7.9) than solitary GGO nodules (17 mm+/-8.1) (P<.001). Air-bronchogram (P=.019), bubble-lucency (P=.004), and pleural retraction (P<.001) were more frequent in solitary GGO nodules. There was no postoperative recurrence except for one patient with multiple GGO nodules and one with solitary GGO nodule.

CONCLUSION

Clinical, pathological, and thin-section CT features of persistent multiple GGO nodules were found to differ from those of solitary GGO nodules. Nevertheless, the two nodule types can probably be followed up and managed in a similar manner because their prognoses were found to be similar.

Lung cancer screening with CT

Lung cancer is the leading cause of cancer death in the United States. Non-small cell lung cancer accounts for 75% to 80% of all lung cancers. There is an impetus to find a screening test that can detect non-small cell lung cancer in its early preclinical stages, when surgical resection is most likely to reduce lung cancer mortality. Although earlier randomized controlled trials of lung cancer screening using chest radiography and sputum cytology failed to show reduced lung cancer mortality, CT is a much more sensitive test for detecting small lung nodules, and has generated considerable enthusiasm as a potential contemporary screening tool for lung cancer.

Association of KRAS polymorphisms with risk for lung adenocarcinoma accompanied by atypical adenomatous hyperplasias

The pulmonary adenoma susceptibility 1 (Pas1) gene affects susceptibility to the development of lung adenomas in mice with a subset of the adenomas progressing to adenocarcinoma (ADC). In this study, genotype distributions for 10 polymorphisms in the human counterparts for three mouse candidate Pas1 genes, KRAS, CASC1/LAS1 and LRMP, were examined in a hospital-based case-control study consisting of 364 lung ADC cases and 253 controls. All the ADC cases were subjected to lobectomy and subsequent pathological investigation of atypical adenomatous hyperplasia (AAH), a putative precursor for peripheral lung ADC, including bronchioloalveolar carcinoma, in the resected lobes. Eighty-one (22%) of the ADC cases carried at least one AAH lesion in addition to the primary ADC and 34 (9%) of them carried multiple AAH lesions. None of the 10 polymorphisms examined showed significant associations with overall lung ADC risk (P > 0.05). However, minor allele carriers for two polymorphisms in the KRAS gene, KRAS-1 and -6, showed significantly increased odds ratios (ORs) for ADC accompanied by multiple AAHs [OR = 3.0; 95% confidence interval (CI) = 1.4-6.2, P = 0.004 and OR = 2.4; 95% CI = 1.1-4.7, P = 0.02, respectively]. Minor haplotypes including the minor allele for the KRAS-6 polymorphism showed increased ORs for ADC accompanied by multiple AAHs, and KRAS transcripts from the minor allele for this polymorphism were more abundantly detected in lung tissues than those from the major allele. Thus, KRAS polymorphisms were indicated to be involved in risk for the development of AAHs that progress to ADC by causing differential KRAS oncogene expression in the lungs.

CT detected indeterminate pulmonary nodules in a chemoprevention trial of fluticasone

INTRODUCTION

In animal models of lung carcinogenesis, inhaled corticosteroids appear to reduce the number of new lung tumors. In a trial of budesonide in smokers with bronchial dysplasia, the proportion of indeterminate CT detected pulmonary nodules that resolved was larger in the treatment group. We performed a secondary analysis of CT data of subjects at risk of lung cancer enrolled in a chemoprevention trial of fluticasone.

METHODS

Subjects with bronchial squamous metaplasia or dysplasia had a baseline chest CT scan. They were randomized to fluticasone or a placebo. After 6 months a repeat CT was performed and the change in number and size of nodules was evaluated.

RESULTS

Two hundred and one subjects were screened. Of the 108 volunteers included in the study, 74 were male, mean age was 53 years and mean number of pack years 48. Baseline: 35 subjects had 91 nodules in total, 62% <4mm. In the fluticasone arm more subjects had a decrease and fewer had an increase in number of nodules, however this trend did not reach statistical significance.

CONCLUSION

In this preliminary study there was a tendency of nodules to resolve, however, studies with CT detected nodules as inclusion criterion are needed.

Molecular Alterations in Atypical Adenomatous Hyperplasia Occurring in Benign and Cancer-bearing Lungs

Atypical adenomatous hyperplasia (AAH) is considered to be a precursor lesion of the lung adenocarcinoma. Several genetic abnormalities have been reported in AAH associated with adenocarcinoma, but little is known about AAH associated with benign lung lesions. To address this we compared the molecular characteristics of AAH present in benign conditions to those coexisting with carcinoma. Seven cases of AAH from resected non-neoplastic lungs (AAH-B) and 12 cases from lungs resected for primary lung carcinoma (AAH-M) were analyzed for loss of heterozygosity (LOH) using 21 polymorphic microsatellite markers situated in proximity to known tumor suppressor genes on chromosomes 3p, 5q, 7p, 9p, 10q, and 17p. Direct DNA sequencing for K-ras mutation was also performed. There was a broad range of LOH in both groups. No LOH was identified in 3 cases (25%) of AAH-M, but all cases of AAH-B showed LOH (P=0.26). Six cases (50%) of AAH-M and 3 cases (43%) of AAH-B showed loss at 1 marker (P=0.99). LOH at 2 or more markers was identified in 3 (25%) cases of AAH-M and 4 (57%) cases of AAH-B (P=0.32). LOH was most frequently detected on chromosomes 3p and 10q in both groups. The difference in overall fractional allelic loss between the 2 groups did not reach statistical significance. K-ras mutations were not identified in either group. Our results showed a significant overlap in LOH patterns between AAH with or without coexistent lung malignancy. Therefore, AAH may represent a smoking induced low-grade neoplastic lesion that may be a precursor lesion of only a subset of invasive lung adenocarcinoma.

Nodular Ground-Glass Opacity at Thin-Section CT: Histologic Correlation and Evaluation of Change at Follow-up

The popularization of computed tomography (CT) in clinical practice and the introduction of mass screening for early lung cancer with the use of CT have increased the frequency of findings of subtle nodules or nodular ground-glass opacity. Nodular ground-glass opacity may be observed in malignancies such as bronchioloalveolar carcinoma and adenocarcinoma, as well as in their putative precursors, such as atypical adenomatous hyperplasia. Nodular ground-glass opacity also may be seen in the presence of benign conditions, including focal interstitial fibrosis, inflammation, and hemorrhage. The persistence of nodular ground-glass opacity over time may be strongly suggestive of an early-stage malignancy, especially if the lesion increases in size or includes a solid component that increases in its extent. Persistent nodular ground-glass opacity also may remain stable in size but show increased attenuation. The more extensive the solid portions of the lesion, the higher the probability of malignancy and the poorer the prognosis. An awareness of the clinical setting, in addition to familiarity with the thin-section CT features of nodular ground-glass opacity at initial and follow-up imaging over several months, can help identify malignancy and achieve an accurate diagnosis. A meticulous evaluation of those CT features, and their correlation with specific histopathologic characteristics, also may enable a more accurate prognosis in cases of neoplastic disease.

CT findings of atypical adenomatous hyperplasia in the lung

Objective

The aim of this study was to analyze the computed tomographic (CT) findings of atypical adenomatous hyperplasia (AAH) in the lung.

Materials and Methods

The CT findings of AAHs in eight patients were retrospectively reviewed. The CT findings of each AAH lesion were evaluated for multiplicity, location, shape, size and internal density of the lesion, the interface between the normal lung and the lesion, the internal features within the lesion and any change of the lesion on the follow-up CT scans (range: 33 to 540 days; average: 145.3 days).

Results

The eight patients consisted of three men and five women (age range: 43-71 years). Six of eight patients were asymptomatic. Four of them (50%) had synchronous malignancies in the lung: adenocarcinoma of the lung (n = 3), and metastatic squamous cell carcinoma from the uterus (n = 1). We could identify and evaluate eleven AAH nodules in seven patients on the CT scans. Three patients had multiple AAHs. Seven of the 11 lesions (64%) were located in the upper lobe. All the AAHs showed a well-defined oval or round shape and pure ground-glass opacity (GGO) without any solid component (size: 3.9×3 mm to 19×17 mm; internal attenuation: -467 to -785 HU). All the AAHs showed no change of their size and internal density on the follow-up CT scans.

Conclusion

Atypical adenomatous hyperplasia is often associated with malignancy. This tumor is shown on CT as persistent well-defined oval or round nodular GGOs without solid components, and it does not change on the follow-up CT.

The utility of B72.3, carcinoembryonic antigen, and Leu M-1 in cell blocks

BACKGROUND

The distinction of bronchioloalveolar carcinoma (BAC) from atypical adenomatous hyperplasia (AAH) or reactive alveolar cell hyperplasia (RAH) can be difficult on aspiration cytology, even when cell block preparations are available. The authors evaluated the usefulness of B72.3, carcinoembryonic antigen (CEA), and Leu M-1 immunostains in differentiating BAC, AAH, and RAH.

METHODS

Immunostains for B72.3, CEA, and Leu M-1 were performed on cell block sections from 11 lung lesions that were diagnosed cytologically as BAC (6 lesions) and "atypical cells, cannot exclude BAC" (5 lesions). Ten histologic sections of AAH and 8 histologic sections of RAH also were stained.

RESULTS

Among the six lesions that had an unequivocal cytologic diagnosis of BAC, all sections were positive for two of three immunostains. Tissue follow-up confirmed BAC in all six lesions. Among the five lesions that were diagnosed as "atypical cells, cannot exclude BAC," four lesions were positive for two of three immunostains, and one lesion was negative for all three immunostains. Subsequent tissue follow-up confirmed BAC in four of these lesions. Follow-up histology of the wedge resection on the lesion in the atypical category that was negative for B72.3, CEA, and Leu M-1 showed only AAH. All 10 lesions that had a histologic diagnosis of AAH and 8 lesions that had a histologic diagnosis RAH were negative for B72.3, CEA, and Leu M-1.

CONCLUSIONS

Positive staining for at least 2 immunostains among B72.3, CEA, and Leu M-1 provided strong supportive evidence for the diagnosis of BAC, and a negative result for all 3 immunostains was helpful in excluding BAC and in differentiating BAC from AAH and RAH.

Synchronous pulmonary atypical adenomatous hyperplasia and metastatic osteosarcoma in a young female

A 17-year-old female underwent metastasectomy of three synchronous lesions in the bilateral lungs under the diagnosis of metastatic osteosarcoma, however, one of them was found to be atypical adenomatous hyperplasia (AAH). Since AAH is very rare among young people, a careful evaluation of high-resolution computed tomographic image is important in determining the operative indications and procedures in patients with multiple metastatic tumors.

Recent developments in biomarkers for the early detection of lung cancer: perspectives based on publications 2003 to present

PURPOSE OF REVIEW

Given the poor prognosis associated with lung cancer, the ability to diagnose lung cancer in its early stages is considered crucial to achieving decreased lung cancer mortality. Herein, we discuss recent advances in biomarker discovery and evaluation of their potential application in the clinical setting.

RECENT FINDINGS

Novel potential biomarkers have been identified via new techniques including cDNA microarray analysis, comparative genomic hybridization, and proteomics. These factors have been evaluated in various validation studies including tissue microarrays, RT-PCR, and assays of bioactivity. The characterization of these potential biomarkers through analysis of pathways that have been associated with neo-plastic transformation may help to identify the precursor lesions that are associated with subsequent progression to invasive carcinoma. In addition, the past year has also produced intriguing results regarding the detection of biomarkers in easily accessible screening specimens such as sputa, serum, and exhaled breath. Recent advances in these aspects of biomarker identification for the early detection of lung cancer are reviewed.

SUMMARY

Identification of new candidate biomarkers and improved applications of previously detected biomarkers show great promise for the ultimate establishment of practical lung cancer screening. While recent studies engender optimism for the creation of clinically applicable screening tests, the biomarkers that have been identified need larger, follow-up validational studies and further characterization as to their biologic importance.

Lung adenocarcinoma associated with atypical adenomatous hyperplasia. A clinicopathological study with special reference to smoking and cancer multiplicity

Atypical adenomatous hyperplasia (AAH) of the lung has been proposed as a possible precursor lesion of adenocarcinoma of the lung. In the present study, we sought to clarify the clinicopathological characteristics of lung adenocarcinoma cases associated with AAH, with special reference to tobacco smoking and the presence of multiple primary carcinomas of pulmonary and extrapulmonary organs. We examined 123 surgically resected lung adenocarcinomas and conducted histopathological diagnoses for AAH and multiple primary pulmonary carcinomas. Clinicopathological characteristics such as age, sex, smoking index, survival, and the presence of extrapulmonary primary carcinomas were obtained from clinical records, and the associations among these factors were examined statistically. Sixteen lung adenocarcinoma patients had accompanying AAH (the AAH group) and 107 cases did not (the NAAH group). The incidence of primary carcinomas in extrapulmonary organs was higher in the AAH group (37.5%; 6/16) than in the NAAH group (12.5%; 13/107) (P = 0.01). Multiple primary lung cancers tended to be more frequent in the AAH group, but the difference was not statistically significant (P = 0.07). Although there was no difference in tobacco smoking between the two groups, all eight cases with multiple primary lung carcinomas were smokers. Furthermore, multiple primary lung carcinomas were found more frequently in smokers of the AAH group (37.5%; 3/8) than in the smokers of the NAAH group (7.2%; 5/69) (P = 0.04). The results suggested that constitutional or genetic factors might predispose patients to the development of AAH together with extrapulmonary primary carcinomas, and that smoking might contribute to the development of multiple primary lung adenocarcinomas, especially in patients with pre-existing AAH.

Detection and discrimination of preneoplastic and early stages of lung adenocarcinoma using hnRNP B1 combined with the cell cycle-related markers p16, cyclin D1, and Ki-67

Heterogeneous nuclear ribonucleoprotein B1 (hnRNP B1), an RNA binding protein, is a useful marker for early detection of lung squamous cell carcinoma because it is overexpressed in the early stages of lung cancer, including bronchial dysplasia, a premalignant lesion of lung squamous cell carcinoma. In the case of adenocarcinoma, we investigated the utility of hnRNP B1 for both detection of early adenocarcinoma and discrimination of non-invasive lesion, atypical adenomatous hyperplasia (AAH) from adenocarcinoma. hnRNP B1, cyclin D1, p16, and Ki-67 were analyzed in lung adenocarcinoma tissues and divided into early and overt adenocarcinoma and AAH, using immunohistochemistry. The intensity of these molecular markers was compared among three groups and also analyzed for 4 patients who showed both adenocarcinoma and AAH. Thirty-six of 54 (67%) adenocarcinoma patients showed positive staining of hnRNP B1: 14/20 (70%) early adenocarcinoma and 22/34 (65%) overt adenocarcinoma. In contrast, overexpression of hnRNP B1 in non-invasive lesion, AAH was observed in only 9% (1/11). Overexpression of cyclin D1 and decrease of p16 were frequently observed in both adenocarcinoma and AAH. These results suggest that hnRNP B1 would be a candidate of molecular marker for detection of early lung adenocarcinoma. In addition, combined analysis of hnRNP B1 and cell cycle-related genes, such as cyclin D1 and p16, might aid in discrimination of AAH from early adenocarcinoma.

Lung adenocarcinoma with bronchioloalveolar carcinoma component is frequently associated with foci of high-grade atypical adenomatous hyperplasia

We assessed the occurrence of atypical adenomatous hyperplasia (AAH) in whole lung lobes with primary cancer lesions. Following surgical resection, tissue specimens were sliced to a thickness of 4 mm (3,641 specimens from 61 cases; mean = 59.7 specimens per case). A total of 119 AAH foci were found and an association was evident in 25 (57%) of 44 adenocarcinomas, 3 (30%) of 10 squamous cell carcinomas, and 2 (29%) of 7 other lung cancers. Histologic evaluation showed that 108 AAH foci were categorized as low-grade and the other 11 as high-grade AAH. These 11 foci of high-grade AAH were present in 7 patients with adenocarcinoma, and in 1 patient there was a synchronous double primary lung adenocarcinoma. High-grade AAH was closely associated with bronchioloalveolar carcinoma (BAC) type adenocarcinoma, and low-grade AAH with non-BAC adenocarcinoma. The mean +/- SD Ki-67 labeling index in high-grade AAH (3.5%+/-2.9%) was significantly higher than for the low-grade index (1.4%+/-1.6%). We propose that foci of high- but not low-grade AAH may be potential precursor lesions of lung adenocarcinoma, especially with the BAC component.

Preneoplastic lesions of the lung

Lung cancer is the leading cause of cancer deaths worldwide. If we can define and detect preneoplastic lesions, we might have a chance of improving survival. The World Health Organization has defined three preneoplastic lesions of the bronchial epithelium: squamous dysplasia/carcinoma in situ; atypical adenomatous hyperplasia; and diffuse idiopathic pulmonary neuroendocrine cell hyperplasia. These lesions are believed to progress to squamous cell carcinoma, adenocarcinoma and carcinoid tumors, respectively. In this review we summarize the data supporting the preneoplastic nature of these lesions, and delve into some of the genetic changes found in atypical adenomatous hyperplasia and squamous dysplasia/carcinoma in situ.

Loss of heterozygosity on chromosomes 9q and 16p in atypical adenomatous hyperplasia concomitant with adenocarcinoma of the lung

Atypical adenomatous hyperplasia (AAH) has recently been implicated as a precursor to lung adenocarcinoma. We previously reported loss of heterozygosity (LOH) in tuberous sclerosis (TSC) gene-associated regions to frequently be observed in lung adenocarcinoma with multiple AAHs. In this study, we analyzed LOH in four microsatellite loci on 9q, including the TSC1 gene-associated region, and four loci on 16p, including the TSC2 gene-associated region, in both 18 AAHs and 17 concomitant lung adenocarcinomas from 11 patients. Seven of 18 (39%) AAHs and 9 of 17 (53%) adenocarcinomas displayed LOH on 9q. Five (28%) AAHs and seven (41%) adenocarcinomas harbored LOH at loci adjacent to the TSC1 gene. Four of 18 (22%) AAHs and 6 of 17 (35%) adenocarcinomas displayed LOH on 16p. One (6%) AAH and five (29%) adenocarcinomas harbored LOH at loci adjacent to the TSC2 gene. These findings may indicate a causal relationship of LOH on 9q and 16p in a fraction of AAH lesions and adenocarcinomas of the lung. Especially, the frequencies of LOH on 9q and at the TSC1 gene-associated region were high. The TSC1 gene or another neighboring tumor suppressor gene on 9q might be involved in an early stage of the pathogenesis of lung adenocarcinoma.

Atypical adenomatous hyperplasia of the lung in autopsy cases

BACKGROUND

Atypical adenomatous hyperplasia (AAH) is a possible precursor lesion of adenocarcinoma of the lung, but very few reports of AAH have focused on the autopsy lung.

METHODS

We intended to clarify the characteristics of AAH in the general population by using 207 autopsy cases, ranging in age from 0 to 90 years old.

RESULTS

A total of 179 eligible cases (86.5%) and 1265 tissue slides (7.0 per case) was examined independently by two pathologists. One hundred seventy-nine autopsy cases consisted of 125 males and 54 females, whose median ages were 38 (range 0-90) and 31 (range 0-81) years old, respectively. AAH was microscopically found in five of 179 autopsy cases (2.8%). The male/female ratio was 5/0 and age distribution was 52-63 years of age (median 57). One of five cases with AAH harbored esophageal carcinoma, but the others had no present or previous malignant neoplasm. One of five lesions was high grade and the others were low grade. All five cases showed positive immunoreactivity for proSP-C, a type II pneumocytes marker, but not for p53, Ki-67 or CEA.

CONCLUSIONS

The incidence of AAH was very low in the general autopsy cases, as compared with the previously reported surgically resected lung and senile autopsy cases, and AAH seems to occur after middle age in general.

MCM2--a promising marker for premalignant lesions of the lung: a cohort study

BACKGROUND

Because cells progressing to cancer must proliferate, marker proteins specific to proliferating cells may permit detection of premalignant lesions. Here we compared the sensitivities of a classic proliferation marker, Ki-67, with a new proliferation marker, MCM2, in 41 bronchial biopsy specimens representing normal mucosa, metaplasia, dysplasia, and carcinoma in situ.

METHODS

Parallel sections were stained with antibodies against MCM2 and Ki-67, and the frequencies of staining were independently measured by two investigators. Differences were evaluated statistically using the two-sided correlated samples t-test and Wilcoxon rank sum test.

RESULTS

For each of the 41 specimens, the average frequency of staining by anti-MCM2 (39%) was significantly (p < 0.001) greater than by anti-Ki-67 (16%). In metaplastic lesions anti-MCM2 frequently detected cells near the epithelial surface, while anti-Ki-67 did not.

CONCLUSIONS

We conclude that MCM2 is detectable in 2-3 times more proliferating premalignant lung cells than is Ki-67. The promise of MCM2 as a sensitive marker for premalignant lung cells is enhanced by the fact that it is present in cells at the surface of metaplastic lung lesions, which are more likely to be exfoliated into sputum. Future studies will determine if use of anti-MCM2 makes possible sufficiently early detection to significantly enhance lung cancer survival rates.

Atypical adenomatous hyperplasia of the lung: a clinicopathological study of 118 cases including cases with multiple atypical adenomatous hyperplasia

BACKGROUND

Atypical adenomatous hyperplasia (AAH) of the lung is a putative precursor lesion of adenocarcinoma, according to many immunohistochemical and genetical studies, but few clinicopathological studies on a large number of cases have been reported. The aim of this study was to clarify the clinicopathological characteristics of lung cancer patients with AAH lesions.

METHODS

A retrospective study was carried out on 508 consecutive primary lung cancer patients operated on at National Cancer Center Hospital East. The relationship between the number and location of AAH lesions and the clinicopathological features of the lung cancer patients was analysed statistically.

RESULTS

A total of 311 AAH lesions were found in 118 (23.2%) of the 508 cases. AAH lesions were detected in 121 of 572 lobes examined, usually in both upper lobes, and occurred most frequently in patients with adenocarcinoma (OR 2.97; 95% CI 1.82 to 4.85). AAH lesions were more frequently detected in patients with multiple primary carcinomas than in those with a single carcinoma (OR 3.06; 95% CI 1.56 to 6.00). The presence of AAH lesions was not significantly correlated with sex, age, smoking status, familial history of malignancy, or preceding malignancy. Patients with multiple AAH lesions were found to have a significantly higher frequency of preceding malignancies.

CONCLUSIONS

The present study highlights the clinicopathological characteristics of AAH lesions, showing them to be significantly associated with both adenocarcinoma and multiple primary carcinoma of the lung and suggesting common factors in the histogenesis of multiple AAH lesions and preceding malignancy.

Early glandular neoplasia of the lung

Although bronchogenic carcinomas progress through a very well defined sequence of metaplasia, dysplasia and carcinoma in situ, very little is known about the early progression of glandular neoplasms of the lung. In particular, the early precursor lesion from which fully malignant adenocarcinomas arise has effectively eluded recognition, at least until recently. Several lines of evidence now implicate atypical adenomatous hyperplasia (AAH) as an initial morphologic stage in multistep lung tumorigenesis. Despite its small size, AAH can be appreciated at the light microscopic level and characterized at the molecular genetic level. Indeed, the genetic characterization of AAH promises to further our understanding of lung cancer development and might facilitate the design of novel strategies for early detection of lung cancer.