Atypical Adenomatous Hyperplasia Lesions Research Articles

Abstract 3933: Comprehensive molecular characterization of mitochondrial mutational landscape across the evolution of lung adenocarcinoma

Abstract The human mitochondrial genome is prone to genetic alterations, which lead to somatic mutations, changes in mtDNA copy number and altered expression of respiratory chain subunits. This is in part due to the fact that mtDNA has a limited ability to repair itself when it is damaged. Although a buildup of somatic mutations in mtDNA has been associated with increased cancer risk, the role of mtDNA alterations in malignant transformation of lung adenocarcinoma has not been addressed. Therefore, a clear understanding of changes in mtDNA along the pathway of lung tumorigenesis is critical for identifying molecular biomarkers related to carcinogenesis and tumor progression. Like all solid tumors, lung adenocarcinoma is thought to be initiated and to progress through a series of genetic alterations, including changes in mtDNA. Lungs resected for primary adenocarcinomas often harbor minute discrete foci of cytologically atypical pneumocyte proliferations designated as atypical adenomatous hyperplasia (AAH). Evidence suggests that AAH represents an initial step in the progression to adenocarcinoma in situ (AIS), minimally invasive adenocarcinoma (MIA) and ultimately fully invasive adenocarcinoma (ADA). In this study we used a unique cohort of 52 patients with matched specimens (n=133) representing different steps of disease progression (AAH, AIS, and MIA) coupled with novel ultra-deep mitochondrial sequencing (mtDNA-Seq) method to assess the mtDNA mutational landscape throughout the continuum of lung adenocarcinoma development. Utilizing a custom bioinformatics workflow, somatic mutations were detected in a subset of the premalignant non-invasive lesions, with overall higher mutational load observed in MIA and ACA specimens. Additionally, large degree of inter-patient heterogeneity were observed for mtDNA copy numbers in conjunction with the clonal histological evolution of pulmonary neoplasia. Moreover, an appreciable number of coding and non-coding mutations from regulatory regions of the mtDNA were detectable in the precursor AAH lesions and the continuum of LUAD progression. Majority of shared mutations showed heteroplasmic transition with increase in fractional abundance in ADA, compared to the AHH lesions, thereby indicating spatial clonal expansion as they progressed histologically. Here we report the first comprehensive characterization of mitochondrial mutational landscape in dynamic evolution of lung adenocarcinoma, and provide insight into the heterogeneity of clonal events associated with the progression from noninvasive to malignant disease. Citation Format: Alka Singh, Santanu Dasgupta, Ashwin L. Koppayi, Lisa Rooper, Vasudha Mishra, David Sidransky, Nishant Agrawal, Karthik Suresh, Evgeny Izumchenko. Comprehensive molecular characterization of mitochondrial mutational landscape across the evolution of lung adenocarcinoma [abstract]. In: Proceedings of the American Association for Cancer Research Annual Meeting 2024; Part 1 (Regular Abstracts); 2024 Apr 5-10; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2024;84(6_Suppl):Abstract nr 3933.

Genomic Evolution in a Patient With Lung Adenocarcinoma With a Germline EGFR T790M Mutation

IntroductionA subset of lung adenocarcinomas (ADs) has been found to have somatic activating mutations in the tyrosine kinase domain of the EGFR gene, associated with response to EGFR tyrosine kinase inhibitor therapy. Rare germline mutations within this domain, including EGFR T790M, have been associated with genetic susceptibility to lung ADs. Using high-throughput sequencing, we elucidate the genomic evolution in tissues from a patient with lung AD carrying a germline EGFR T790M mutation. MethodsWe performed microdissection, targeted panel, and whole-exome sequencing to molecularly characterize multiple foci of atypical adenomatous hyperplasia (AAH), in situ and invasive components of AD, normal lung tissue, and whole blood from the patient. Normal lung tissue was analyzed for potential acquired somatic genome alterations (“field effect”). ResultsAll lesions harbored a secondary somatic EGFR mutation, either L858R or L861Q, in addition to the germline T790M mutation. Clear overlap was observed between the somatic profiles of in situ and invasive AD components, confirming clonal relatedness. AAH lesions shared few to no somatic alterations with the AD, suggesting clonal independence. No robust evidence of field effect was identified in the normal lung tissue. ConclusionsSomatic EGFR mutations are early events in the pathogenesis of lung ADs arising in the context of germline EGFR T790M. Synchronous AAH lesions seem to be independent. Stepwise genomic evolution is observed in association with invasiveness of the neoplastic cell population.

Peculiarities of pathomorphological diagnostics of prostate gland adenosis and presentation of clinical case

Background. Atypical adenomatous hyperplasia (AAH) or adenosis of the prostate gland is a pseudoneoplastic process which according to its tissue-architectural and cytological morphological peculiarities often resemble small acinar adenocarcinoma. In modern specialized literature few clinical-morphological peculiarities related to both pathological processes AAH and prostate adenocarcinoma (PA) were described. First, the incidence of AAH increases with age, as does the incidence of PA. Second, AAH lesions are often multifocal, as is PA, and they are located very closely to cancer areas. Third, the incidence of AAH increases in the presence of cancer and, vice versa, cancer incidence increases in cases of diagnosed AAH. Fourth, there are numbers of morphological changes, typical for AAH, which are closely related to highly differentiated PA. Objective of current work is study, analysis and possibilities of application in practice of differential diagnostic criteria of AAH and small acinar carcinomas of the prostate. Methods. In the case proposed for consideration during primary histological examination of prostate gland biopsy taken from 74-year old man AAH was detected. Results and conclusion. However, certain pathomorphological signs more typical for prostatic carcinomas, as well as results of immunohistochemical examination more characteristic for malignant epithelial adenogenous tumors served as the basis for verification of prostatic adenocarcinoma.

Prenatal stress enhances NNK-induced lung tumors in A/J mice.

Children born to women who experience stress during pregnancy have an increased risk of cancer in later life, but no previous animal studies have tested such a link. We questioned whether prenatal stress (PS) in A/J mice affected the development of lung tumors after postnatal response to tobacco-specific nitrosamine, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanone (NNK). Timed-bred A/J mice were randomly assigned on gestation day 12.5 to PS by restraint for 5 consecutive days or control (no restraint). Adult offspring of control and stressed pregnancies were all treated with three NNK injections (50 mg/kg every other day) and euthanized 16 weeks later to examine their lungs. Compared with controls, PS dams exhibited significantly increased levels of plasma corticosterone, increased adrenal weights and decreased fetus weights without fetal loss. Prenatally stressed litters had a significantly higher neonatal death rate within first week of life, and surviving male and female offspring developed lung epithelial proliferations with increase multiplicity, increased area and aggressive morphology. PS also induced more advanced atypical adenomatous hyperplasia lesions. We found no difference in lung NNK-derived methyl DNA adducts, but PS did significantly enhance CD3+ T cell and Foxp3+ T cell tumor infiltration. PS significantly increases multiplicity, area of NNK-induced lung tumors and advanced morphology. PS did not affect production of NNK-derived methyl DNA adducts but did increase lymphocytic infiltration of lung tumors. To our knowledge, this is the first animal model of PS with evaluation of cancer development in offspring.

The Immune Contexture Associates with the Genomic Landscape in Lung Adenomatous Premalignancy.

Epithelial cells in the field of lung injury can give rise to distinct premalignant lesions that may bear unique genetic aberrations. A subset of these lesions may escape immune surveillance and progress to invasive cancer; however, the mutational landscape that may predict progression has not been determined. Knowledge of premalignant lesion composition and the associated microenvironment is critical for understanding tumorigenesis and the development of effective preventive and interception strategies. To identify somatic mutations and the extent of immune cell infiltration in adenomatous premalignancy and associated lung adenocarcinomas, we sequenced exomes from 41 lung cancer resection specimens, including 89 premalignant atypical adenomatous hyperplasia lesions, 15 adenocarcinomas in situ, and 55 invasive adenocarcinomas and their adjacent normal lung tissues. We defined nonsynonymous somatic mutations occurring in both premalignancy and the associated tumor as progression-associated mutations whose predicted neoantigens were highly correlated with infiltration of CD8+ and CD4+ T cells as well as upregulation of PD-L1 in premalignant lesions, suggesting the presence of an adaptive immune response to these neoantigens. Each patient had a unique repertoire of somatic mutations and associated neoantigens. Collectively, these results provide evidence for mutational heterogeneity, pathway dysregulation, and immune recognition in pulmonary premalignancy.Significance: These findings identify progression-associated somatic mutations, oncogenic pathways, and association between the mutational landscape and adaptive immune responses in adenomatous premalignancy.See related commentary by Merrick, p. 4811.

Value of TSCT Features for Differentiating Preinvasive and Minimally Invasive Adenocarcinoma From Invasive Adenocarcinoma Presenting as Subsolid Nodules Smaller Than 3 cm

To distinguish preinvasive (adenocarcinoma in situ/atypical adenomatous hyperplasia) and minimally invasive adenocarcinoma (MIA) from invasive adenocarcinoma (IA) appearing as solitary subsolid nodules (SSNs) less than 3 cm based on thin-section computed tomography (TSCT) features to guide therapeutic approaches. A total of 154 lesions that were histopathologically confirmed to have pre/minimally invasive adenocarcinoma (hereafter pre/MIA) and IA presenting as part-solid nodules (PSNs) or pure ground-glass nodules (pGGNs) were retrospectively reviewed. The TSCT features, including diameter, area, CT value, shape, air bronchogram, margins, and location, were compared and assessed. Receiver operating characteristic analyses were conducted to determine the cut-off values for the qualitative variables and their diagnostic performances. Of 154 nodules, 89 IA, 53 MIA, eight adenocarcinoma in situ, and four atypical adenomatous hyperplasia lesions were found. Univariate and multivariate logistic regression of the pre/MIA and IA lesions were compared and analyzed among PSNs and pGGNs. Among pGGNs, a significant difference was found in the area (p = 0.004, odds ratio [OR] = 0.124, 95% confidence interval [CI] = 0.300-0.515) between the pre/MIA and IA groups. In PSNs, significant differences were found in the diameter (p = 0.001, OR = 0.171, 95% CI = 0.063-0.467) and CT value (p = 0.001, OR = 0.996, 95% CI = 0.993-0.998) between the pre/MIA and IA groups. According to the corresponding receiver operating characteristic curves, the optimal cut-off tumor area in pGGNs to differentiate pre/MIA from IA was 0.595 cm2. A higher CT value of the lesion (≥ -298.500 HU) and a larger diameter (≥1.450 cm) in PSNs were significantly associated with IA. Imaging features from TSCT contribute to distinguishing pre/MIA from IA in solitary subsolid nodules and may contribute to guide the clinical management of these lesions.

Molecular evidence supporting the precursor nature of atypical adenomatous hyperplasia of the prostate

Atypical adenomatous hyperplasia (AAH) of the prostate is characterized by lobular proliferation of closely packed small acini. It is hypothesized that AAH is a precursor lesion for low-grade prostate cancer arising from the transition zone. Telomere dysfunction is common during malignant transformation of epithelia. In this study, we investigate telomere shortening in AAH (n = 93), high-grade prostatic intraepithelial neoplasia (HGPIN) ( n = 68), and prostatic adenocarcinoma (PCA) ( n = 70) using quantitative fluorescence in situ hybridization. Twenty percent (19 of 93) of AAH specimens, 68% (46 of 68) of HGPIN, and 83% (58 of 70) of PCA showed significant telomere shortening. Thirty-two percent of AAH lesions had α-methylacyl-CoA racemase (AMACR) expression, a sensitive and specific marker for HGPIN and PCA. AMACR expression in AAH was seen more frequently in AAH foci with telomere shortening or coexisting PCA. Our findings indicate that a subset of AAH lesions have telomere shortening and AMACR expression, suggesting that these foci may be precursors for PCA.

Is a 5-mm diameter an appropriate cut-off value for the diagnosis of atypical adenomatous hyperplasia and adenocarcinoma in situ on chest computed tomography and pathological examination?

Preinvasive lesions, such as atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS), usually appear as pure ground-glass nodules (pGGNs) on thin-section computed tomography (TSCT). AAH is usually less than 5 mm wide on imaging and pathological examinations. We aimed to determine whether a 5-mm cut-off value was appropriate for the diagnosis of AAH and AIS. We retrospectively analyzed the performance of TSCT in evaluating 80 pathologically confirmed preinvasive lesions (33 AAH lesions in 31 patients and 47 AIS lesions in 45 patients). We compared the following characteristics between the AAH and AIS groups: lesion diameter, density, rim, lobulation, spiculation, vacuole sign, aerated bronchus sign, pleural indentation sign, and pathological findings. All 80 lesions appeared as pGGNs. On TSCT, the average diameter of AAH lesions (6.0±1.64 mm) was significantly smaller than that of AIS lesions (8.7±3.16 mm; P<0.001). The area under the curve (AUC) for diameter was 0.792, and the best diagnostic cut-off value was 6.99 mm. On gross pathological examination, the average diameter of AAH lesions (4.6±1.99 mm) was significantly smaller that of AIS lesions (6.8±2.06 mm; P<0.001). The AUC was 0.794, and the best diagnostic cut-off value was 4.5 mm. The vacuole sign was common in AIS (P=0.021). AAH did not significantly differ from AIS (P>0.05) in terms of average CT value, uniformity of density, morphology, rim, lobulation, spiculation, pleural indentation sign, and aerated bronchus sign. Lesion size and the vacuole sign were beneficial in the diagnosis of AAH and AIS. The vacuole sign was common in AIS. The best diagnostic cut-off value of nodular diameter for differentiating between AAH and AIS was 6.99 mm on TSCT and 4.5 mm on gross pathology.

Targeted next-generation sequencing for analyzing the genetic alterations in atypical adenomatous hyperplasia and adenocarcinoma in situ.

Atypical adenomatous hyperplasia (AAH) and adenocarcinoma in situ (AIS) have been defined as preinvasive pulmonary adenocarcinoma lesions according to the 2015 World Health Organization lung adenocarcinoma classification. We aimed to search for the most common gene mutations in patients with AAH and AIS and investigate the distinctions between the two groups at the molecular level. We performed targeted next-generation sequencing on 18 cases with AAH and 28 cases with AIS to screen for mutations with the Ion Torrent Oncomine Solid Tumor DNA panel. ALK and ROS1 fusions were detected by real-time PCR. Forty-six mutations were identified in 29 cases (76.1%), including 9 (50%) of 18 cases with AAH and 20 (71.4%) of 28 cases with AIS, in the following genes: EGFR, BRAF, KRAS, ERBB2, TP53, and FGFR3. The mutations in EGFR, BRAF, KRAS, ERBB2, and TP53 genes were more common in AIS lesions than in AAH lesions, whereas the FGFR3 gene was more frequently mutated in AAH compared to AIS. ALK and ROS1 fusions were not detected in any of the lesions. Based on the molecular evidence, the proposal that AAH and AIS are preinvasive lesions of pulmonary adenocarcinomas is of great significance, and it is necessary to distinguish AAH from AIS. Our study provided insights into the genetic alterations in the early stage of lung adenocarcinoma, which could be beneficial for the pathologic diagnosis and early detection of these lesions.

Morphological factors differentiating between early lung adenocarcinomas appearing as pure ground-glass nodules measuring ≤10mm on thin-section computed tomography.

BackgroundWe aimed to compare the morphological features of pure ground-glass nodules (GGNs; diameter, ≤10 mm) on thin-section computed tomography (TSCT) with their histopathological results in order to identify TSCT features differentiating between atypical adenomatous hyperplasia (AAH), adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA).MethodsBetween January and December 2013, 205 pure GGNs with a diameter ≤10 mm on TSCT were pathologically confirmed as AAH (40), AIS (95) or MIA (70) lesions. The patients’ age and sex were recorded. The morphological features were evaluated, and maximum diameter and mean CT value were measured for each nodule. F test, Pearson χ2 test, Fisher exact test and multinomial logistic regression analysis were used to identify factors differentiating between AAH, AIS and MIA. Receiver operating characteristic (ROC) curve analysis was performed for maximum diameter and mean CT value.ResultsF test, Pearson χ2 test and Fisher exact test revealed that maximum diameter (P <0.00001), mean CT value (P =0.005), type of interface (P =0.005) and presence of air bronchograms (P =0.02, n =44) significantly differed among the AAH, AIS and MIA groups. Multinomial logistic regression analysis showed that maximum diameter ≥6.5 mm, a well-defined and coarse interface indicated AIS or MIA rather than AAH; air bronchograms differentiated MIA from AAH; but these parameters did not differentiate between AIS and MIA. A mean CT value less than −520 HU indicated AAH or AIS rather than MIA, but did not differentiate between AAH and AIS.ConclusionsIn the case of pure GGNs measuring ≤10 mm, a maximum diameter ≥6.5 mm, a well-defined and coarse interface indicate AIS or MIA rather than AAH; an air bronchogram can differentiate MIA from AAH. A mean CT value less than −520 HU indicates AAH or AIS rather than MIA.

Abstract 3667: Attenuation of NF-κB signaling in myeloid cells enhances urethane-induced lung tumorigenesis via neutrophil-derived IL-1β

Abstract The transcription factor Nuclear Factor κB (NF-κB) is a master regulator of inflammation, and its activation is associated with tumorigenesis in a variety of cancers. Our group and others have shown that NF-κB signaling in lung epithelial cells is critical for lung carcinogenesis. However, pharmaceutical inhibition of NF-κB signaling has not been effective for the treatment of lung tumorigenesis in animals or humans for reasons that remain unknown. We hypothesized that attenuation of NF-κB signaling in myeloid cells contributes to inefficacy of NF-κB-targeted therapies by unmasking pro-tumorigenic characteristics of inflammatory cells. For our studies, we utilized mice with IKKβ deleted specifically in myeloid cells (IKKβΔmye) and induced lung tumorigenesis with a single intraperitoneal injection of the lung carcinogen urethane (1g/kg). We found that IKKβΔmye mice developed more atypical adenomatous hyperplasia (AAH) lesions at 6 weeks and more lung tumors at 16 weeks after urethane compared to WT mice. These histological differences were correlated with enhanced lung inflammation in IKKβΔmye mice which was observed 1 week after urethane and persisted for up to 6 weeks. Flow cytometric analysis of myeloid cell populations revealed that IKKβΔmye mice contained more pulmonary neutrophils at 1 and 6 weeks after urethane compared to WT mice. In bone marrow chimeras generated by transplantation of bone marrow from IKKβΔmye or WT donors into recipient NF-κB reporter mice, we showed that depletion of neutrophils using Ly6G antibody treatment (100 ug/twice weekly IP injection) during the first 6 weeks of lung carcinogenesis blocked NF-κB activation in stromal cells and reduced tumor multiplicity in IKKβΔmye mice to levels observed in urethane-treated WT mice. Thus, these studies indicated that neutrophils play an important role in lung tumorigenesis during early tumor development and may do so by limiting NF-κB activation in lung epithelial cells. Evaluation of cytokines in the lungs of WT and IKKβΔmye mice at 1 week after urethane revealed higher levels of IL-1β in IKKβΔmye mice compared to WT mice. Further examination of myeloid cells sorted 1 week after urethane identified neutrophils as the key producers of IL-1β in the lungs of IKKβΔmye mice. Neutralization of IL-1 signaling by IL-1 receptor antagonist (IL-1ra) treatment during the first 4 weeks of carcinogenesis decreased the number of AAH lesions in IKKβΔmye mice 6 weeks after urethane and reduced the number of tumors at 16 weeks in IKKβΔmye mice. Taken together, our data suggest that neutrophils can support tumor promotion through production and secretion of IL-1β, which may activate pro-tumorgenic NF-κB signaling in the lung epithelium. We speculate that the paradoxical increase in inflammation and IL-1β production resulting from NF-κB inhibition in myeloid cells contributes to the lack of effectiveness of NF-κB inhibitors in patients with lung cancer. Citation Format: Allyson McLoed, Rinat Zaynagetdinov, Taylor Sherrill, Fiona Yull, Timothy Blackwell. Attenuation of NF-κB signaling in myeloid cells enhances urethane-induced lung tumorigenesis via neutrophil-derived IL-1β. [abstract]. In: Proceedings of the 105th Annual Meeting of the American Association for Cancer Research; 2014 Apr 5-9; San Diego, CA. Philadelphia (PA): AACR; Cancer Res 2014;74(19 Suppl):Abstract nr 3667. doi:10.1158/1538-7445.AM2014-3667

Analysis of pre‐invasive lung adenocarcinoma lesions on thin‐section computerized tomography

Recent studies have revealed a potential relationship between the presence of ground glass opacity (GGO) on regular computerized tomography (CT) and adenocarcinomas. To investigate features of pre-invasive lung adenocarcinoma lesions on thin-section CT. We evaluated 59 cases of atypical adenomatous hyperplasia (AAH) and 35 cases of adenoma in situ (AIS) confirmed by histopathology. Comparison of thin-section CT features, such as size, shape, margin, internal characteristics, and adjacent structures of pre-invasive lesions were analyzed. Lesions were further classified to pure ground glass opacity (pGGO) and mixed ground glass opacity (mGGO). Differences were analyzed using Chi-square or Fisher tests. There were significant differences in lobulation, spiculation, and bubble lucency between pGGO and mGGO (P < 0.05), while no differences in air bronchogram, pleural indentation, or vascular morphological changes were identified (P > 0.05). In the group of pGGO, AAH and AIS lesions did not differ significantly in size (P > 0.05), while significant differences were found with respect to lobulation, spiculation, pleural indentation, and vascular morphological changes (P < 0.05). In the group of mGGO, AAH and AIS lesions were significantly different with respect to size (P < 0.05), while no differences were found in lobulation, spiculation, bubble lucency, air bronchogram, or pleural indentation (P > 0.05). Only vascular morphological changes were significantly different between AAH and AIS lesions (P < 0.05). The features of thin-slice CT of AAH and AIS reflected the corresponding morphological changes from AAH progressing to AIS or adenocarcinoma.

Abstract 2875: NF-κB signaling in myeloid cells limits urethane-induced lung tumorigenesis.

Abstract The transcription factor Nuclear Factor κB (NF-κB) is a master regulator of inflammation, and its activation is associated with tumorigenesis in a variety of cancers. Our group has shown that NF-κB signaling in lung epithelial cells is critical for lung tumor formation. However, the role of NF-κB in other cell types, such as myeloid cells, during lung carcinogenesis is uncertain. We hypothesized that NF-κB signaling in myeloid cells (macrophages, monocytes, and neutrophils) promotes lung tumorigenesis by facilitating lung inflammation. Surprisingly, we found that mice with myeloid cell-targeted IKKβ deletion (IKKβΔmye mice) developed significantly more tumors than wild-type (WT) mice 4 months following a single intraperitoneal (IP) injection of the lung carcinogen urethane (1g/kg). IKKβΔmye mice exhibited a paradoxical increase in the proinflammatory cytokines IL-1β, TNFα, and CXCL1 at 1 and 2 weeks after urethane treatment, and a more than 3-fold higher influx of CD11b+Ly-6G+ cells into IKKβΔmye lungs compared to WT lungs was observed by flow cytometry 1 week post-urethane. By 6 weeks after urethane, IKKβΔmye mice developed more lung inflammation than WT mice, which was accompanied by an increased burden of atypical adenomatous hyperplasia lesions. Flow cytometric analysis of inflammatory cell populations at this time point revealed a sustained increase in granulocytic cells, indicated by significantly higher numbers of CD11b+Gr-1hi cells in the lungs of IKKβΔmye mice compared to WT mice. Depletion of granulocytic cells using Ly-6G antibody treatment (50ug/weekly IP injection) during the first 6 weeks of urethane-induced lung carcinogenesis reduced lung NF-κB activation and lung tumor incidence in IKKβΔmye mice to levels observed in urethane-treated WT mice, indicating that granulocytic cells play an important role in lung tumorigenesis during early tumor development and may do so by limiting NF-κB activation in lung epithelial cells. Together, our data suggest that the impact of NF-κB signaling on lung tumorigenesis is cell type specific and that myeloid NF-κB signaling limits urethane-induced inflammation and lung tumorigenesis. Granulocytes are important players during early lung tumor promotion, and we propose that they promote lung carcinogenesis through interactions that increase survival and/or proliferation of mutated lung epithelial cells. Citation Format: Allyson McLoed, Rinat Zaynagetdinov, Taylor Sherrill, Fiona Yull, Timothy Blackwell. NF-κB signaling in myeloid cells limits urethane-induced lung tumorigenesis. [abstract]. In: Proceedings of the 104th Annual Meeting of the American Association for Cancer Research; 2013 Apr 6-10; Washington, DC. Philadelphia (PA): AACR; Cancer Res 2013;73(8 Suppl):Abstract nr 2875. doi:10.1158/1538-7445.AM2013-2875

One-dimensional mean computed tomography value evaluation of ground-glass opacity on high-resolution images

ObjectiveDifferentiation of atypical adenomatous hyperplasia (AAH), bronchioloalveolar carcinoma (BAC), and invasive carcinoma on computed tomography (CT) is useful for determining “follow-up or resection” strategies for lesions displaying ground-glass opacity (GGO). The purpose of this study is to evaluate one-dimensional quantitative CT values of GGO on high-resolution CT (HRCT) images using computer-aided diagnosis.MethodsBetween April 2001 and March 2010, a total of 44 nodules in 42 patients with pure or mixed GGOs ≤2 cm were retrospectively evaluated. Maximum diameter and one-dimensional mean CT (m-CT) value of the diameter were measured using a computer graphics support system (HOPE/DrABLE-EX, Fujitsu, Tokyo, Japan) that displays a CT density profile across the tumor.Resultsm-CT values were −682 ± 64 HU (range) for AAH lesions, −544 ± 179 (range) for Type A lesions, −496 ± 147 (range) for Type B lesions, and −371 ± 142 (range) for invasive lesions. AAH lesions had a significantly lower m-CT value than Type B lesions. AAH, Type A, and Type B lesions had significantly lower m-CT values than invasive lesions (p < 0.05). All seven GGO lesions with a maximum diameter ≤1 cm and m-CT value ≤−600 HU were pre-invasive lesions, while 16 of 22 (73 %) cases with maximum diameter >1 cm and m-CT value >−600 HU were invasive lesions.ConclusionObservation may be indicated for GGO lesions with a maximum diameter ≤1 cm and m-CT value ≤−600 HU.

A Critical Role for Macrophages in Promotion of Urethane-Induced Lung Carcinogenesis

Macrophages have established roles in tumor growth and metastasis, but information about their role in lung tumor promotion is limited. To assess the role of macrophages in lung tumorigenesis, we developed a method of minimally invasive, long-term macrophage depletion by repetitive intratracheal instillation of liposomal clodronate. Compared with controls treated with repetitive doses of PBS-containing liposomes, long-term macrophage depletion resulted in a marked reduction in tumor number and size at 4 mo after a single i.p. injection of the carcinogen urethane. After urethane treatment, lung macrophages developed increased M1 macrophage marker expression during the first 2-3 wk, followed by increased M2 marker expression by week 6. Using a strategy to reduce alveolar macrophages during tumor initiation and early promotion stages (weeks 1-2) or during late promotion and progression stages (weeks 4-16), we found significantly fewer and smaller lung tumors in both groups compared with controls. Late-stage macrophage depletion reduced VEGF expression and impaired vascular growth in tumors. In contrast, early-stage depletion of alveolar macrophages impaired urethane-induced NF-κB activation in the lungs and reduced the development of premalignant atypical adenomatous hyperplasia lesions at 6 wk after urethane injection. Together, these studies elucidate an important role for macrophages in lung tumor promotion and indicate that these cells have distinct roles during different stages of lung carcinogenesis.

Is atypical adenomatous hyperplasia of the prostate a precursor lesion?

Alpha-methylacyl-CoA racemase (AMACR) is highly expressed in prostatic adenocarcinoma. The precursor nature of atypical adenomatous hyperplasia (AAH) is uncertain. One hundred twenty-one AAH foci from 101 patients who underwent transurethral prostatic resection or prostatectomy were immunohistochemically analyzed for AMACR, high molecular weight cytokeratin 34βE12, and p63 expression by a triple antibody (PIN4) cocktail stain. Sixty-eight foci (56%) of AAH showed no AMACR immunostaining. Fourteen cases (12%) showed weak AMACR immunoreactivity in 1-9% of lesional cells. Sixteen cases (13%) showed strong immunopositivity for AMACR in >50% of lesional cells. AMACR expression in AAH was significantly higher in cases in which coexisting PCA was present, compared with its expression in AAH foci without coexisting PCA (P = 0.03). Strong diffuse AMACR positivity in over 50% of lesional cells was seen almost exclusively in AAH foci with coexisting PCA (P = 0.002). AMACR expression in AAH showed no correlation with patient age (P = 0.38), specimen type (P = 0.35), prostate weight (P = 0.80), zonal location (P = 0.50), distance to cancer (P = 0.28), Gleason score (P = 0.06), or pathologic stage (P = 0.23). Increased AMACR expression showed a negative correlation with the size of AAH foci (P = 0.03). All AAH lesions showed fragmented basal cell layers, highlighted by p63 and high molecular weight cytokeratin staining. A significant percentage of AAH cases show stronger and more extensive AMACR expression when associated with prostatic adenocarcinoma, as compared to AAH foci found without coexisting prostate cancer. Our data provide additional evidence linking AAH to prostatic adenocarcinoma.

Multiple Focal Pure Ground-Glass Opacities on High-Resolution CT Images: Clinical Significance in Patients With Lung Cancer

The purpose of this study was to evaluate the clinical significance of multiple focal pure ground-glass opacities (GGOs) on high-resolution CT images of patients with lung cancer. The cases of 23 patients with proven lung cancer and associated multiple focal pure GGOs on high-resolution CT images were retrospectively reviewed. The number, size, distribution, and morphologic characteristics of focal pure GGOs were evaluated. Serial changes in focal pure GGOs that were not surgically resected were analyzed at follow-up high-resolution CT. The number of focal pure GGOs was 196 in total. The size of the opacities ranged from 2 to 30 mm in largest diameter. Lung cancer and focal pure GGOs were seen in the same lobe and/or in the other lobes. One hundred seventy-one of the lesions (87%) had a well-defined border or round shape. Histologic findings were obtained for 15 lesions representing 74 focal pure GGOs that were surgically resected: 11 atypical adenomatous hyperplasia lesions, three bronchioloalveolar carcinomas, and one lesion of focal fibrosis. In 110 of the cases of focal pure GGOs, all of which were followed up with HRCT for a median duration of 1,351 days, the size of 105 lesions (95%) did not change, the size of one decreased, and four lesions disappeared. The size of most focal pure GGOs associated with lung cancer did not change during the follow-up period. Most of the small number of lesions histologically diagnosed were atypical adenomatous hyperplasia or bronchioloalveolar carcinoma. These data justify the therapeutic strategy of resecting the primary tumor without therapeutic intervention in the remaining focal pure GGOs.

Epidermal Growth Factor Receptor Mutations in Multicentric Lung Adenocarcinomas and Atypical Adenomatous Hyperplasias

The mechanisms of generation and progression of multicentric lung adenocarcinoma (AD), bronchioloalveolar carcinoma (BAC), and atypical adenomatous hyperplasia (AAH) in the peripheral lung is not well known. In this study, we analyzed epidermal growth factor receptor (EGFR) mutations in the cases of multicentric AD, BAC, and AAH to reveal the role of EGFR mutation in their generations and progressions. Ninety-seven AAH, BAC, or AD lesions less than 3 cm in size in 26 patients were surgically resected. Of these, EGFR mutations of the nodules with the highest and the second highest grade of histologic malignancy were examined in each patient by using the peptide nucleic acid-locked nucleic acid polymerase chain reaction (PNA-LNA PCR) clamp method. EGFR mutations could be examined in 48 nodules in the 26 patients. The EGFR mutations were found more frequently in lesions with higher histologic malignancy, ie, 9 of 10 ADs (90%), 16 of 28 BACs (57%), and one of 10 AAHs (10%). In 22 patients who could be examined of EGFR mutations for the two lesions in each patient, only two patients (9%) had the same mutation patterns between the two lesions, whereas 15 patients (68%) had the different statuses and the remaining five (23%) had no mutations. Our data demonstrated that EGFR mutations seem to contribute to the acquisition of malignant potential in the AAH-AD sequence and occur independently in each lesion and in the cases of multicentric AD, BAC, and AAH.

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.

Immunohistochemical Study of Fibrosis and Adenocarcinoma in Dominant-Negative p53 Transgenic Mice Exposed to Chrysotile Asbestos and Benzo(a)pyrene

We evaluated the mechanisms using immunohistochemistry whereby chrysotile asbestos and benzo(a)pyrene (BaP) instilled intratracheally into lung-specific dominant-negative p53 (dnp53) mice might interact in causing lung carcinomas and fibrosis. Chrysotile asbestos and benzo(a)pyrene (BaP) were instilled intratracheally into lung-specific dominant-negative p53 (dnp53) and control mice. The mice were sacrificed at 12 months and their lungs examined for lung carcinomas and fibrosis. Immunostains for proteins related to apoptosis, fibrogenesis, matrix remodeling and inflammation were performed. The dnp53 mice had increased numbers of lung adenocarcinomas with BaP alone and the combination of chrysotile and BaP (the latter was additive but not significant). Several atypical adenomatous hyperplasia lesions were found in the combined treatment group. dnp53 and FVBN control mice developed nodular buds of fibrotic lung tissue after chrysotile asbestos exposure that were localized in respiratory bronchioles; these lesions had significant increases in immunohistochemical staining for TGF-beta, MMP-7 and -9, MIG-1, and SDF-1. Fibrotic lesions in mice exposed to chrysotile had increased collagen demonstrated by picrosirius red staining. The dnp53 mice with adenocarcinomas had increased SDF-1, TGF-beta, MMP-9 and -7, Cyclin D, and MIG-1 immunostaining in the chrysotile and combined treatment groups. We conclude that BaP and the combination of BaP plus chrysotile asbestos are potent inducers of adenocarcinoma in dnp53 mice and that the inflammatory cytokines and proteases MMP-7 and -9, MIG-1, and SDF-1, and growth factors Cyclin D and TGF-beta are increased in the specific lesions.