A case of double primary adenocarcinoma of the lung with multiple atypical adenomatous hyperplasia

Clinicopathologic analysis of multiple (five or more) atypical adenomatous hyperplasias (AAHs) of the lung: evidence for the AAH-adenocarcinoma sequence

OBJECTIVE

Clarification of the clinicopathologic characteristics of patients with multiple atypical adenomatous hyperplasias (AAHs).

MATERIALS AND METHODS

The subjects were 1,639 patients who underwent lobectomy or pneumonectomy for lung tumors. The clinicopathologic features of the AAHs in the lung background and the main tumors were examined with regard to the number and the size of the AAHs, the incidence and histology of adenocarcinomas (ADs), and the outcome.

RESULTS

Thirty-two patients (2.0%) had 5 or more AAHs (ranging from 5 to 171), being present predominantly in the upper lobe (86%) and in women (75%). Among the 794 AAHs, 495 (62%) measured less than 1 mm, 170 (22%) measured 1 to less than 2 mm, 118 (15%) measured 2 to less than 5 mm, and 11 (1%) measured 5 to less than 10 mm. Twenty-eight patients (88%) had AD (1 in 18 patients and 2 to 6 in 10 patients). Thirty-two of the 51 patients with ADs (63%) had an AAH component. The incidence of ADs among the total of both AAHs and ADs was 6.0% (51 of 845). The 5-year cancer-free survival rate was 71.4%.

CONCLUSION

Five or more AAHs were seen in the background in 2.0% of lung tumors. Most of the AAHs were small, measuring less than 2 mm, and few exceeded 5 mm. Most of the patients had ADs, which were histologically suggested to be derived from AAH. However, the incidence of the AAH-AD sequence was considered to be low at the tumor basis, and the outcome of ADs was not very favorable.

Stepwise progression of pulmonary adenocarcinoma--clinical and molecular implications

Stepwise progression of pulmonary adenocarcinoma is described from the viewpoint of both pathology and molecular biology. Pulmonary adenocarcinoma develops to invasive carcinoma through atypical adenomatous hyperplasia, adenocarcinoma in situ and minimally invasive adenocarcinoma. The Noguchi classification is well correlated with this sequential histological progression. On the other hand, in terms of molecular biology, p16 gene inactivation, EGFR mutation and KRAS mutation are early events, and tumors progress to invasive adenocarcinoma as a result of p53 mutation, loss of various chromosomes and other genetic abnormalities.

Establishment of an immortalized cell line from a precancerous lesion of lung adenocarcinoma, and genes highly expressed in the early stages of lung adenocarcinoma development

Atypical adenomatous hyperplasia (AAH) is classified as a precancerous lesion of lung adenocarcinoma. We established an immortalized AAH cell line (PL16T) and a human non-neoplastic bronchial epithelial cell line (PL16B) from the same patient by transfection with the gene for SV40 large T antigen. The expression profile of PL16T was compared with that of PL16B by the suppression subtractive hybridization method. From 704 selectively hybridized clones, we finally selected 25 fragments of mRNA that showed transcription levels more than three times higher in PL16T than in PL16B. Thirteen (52%) and eight (32%) of them encoded tumor-associated calcium signal transducer 2 (TACSTD2) and S100 calcium binding protein A2 (S100A2), respectively. The high transcription of TACSTD2 and S100A2 in PL16T was confirmed by in situ hybridization. In normal lung tissue, both TACSTD2 and S100A2 were expressed at very low levels, but seven and five of 14 AAH were positive for TACSTD2 and S100A2, respectively. The frequency of TACSTD2 positivity was increased in 16 of 22 bronchioloalveolar carcinomas (BAC) and adenocarcinoma with mixed subtype with BAC component (mixed BAC). Positivity for S100A2 occurred in four of 22 BAC and mixed BAC. The abnormal transcription of TACSTD2 and S100A2 are thought to be unique molecular markers of the preinvasive stage of lung adenocarcinoma.

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.

Is high-grade adenomatous hyperplasia an early bronchioloalveolar adenocarcinoma?

Atypical adenomatous hyperplasia (AAH) is a probable forerunner of bronchioloalveolar carcinoma (BAC) and pulmonary adenocarcinoma (AC) of mixed type. The present study analysed four low-grade AAHs, 13 high-grade AAHs, two BACs, nine mixed ACs, and one squamous cell carcinoma derived from 13 patients using comparative genomic hybridization. The average number of chromosomal aberrations was 1.2 in low-grade AAH, 9.6 in high-grade AAH, and 12.5 in AC. A high degree of overlap of genetic changes was found in high-grade AAH, BAC, and AC within individual patients. The high number of aberrations and the degree of shared aberrations found in high-grade AAH and AC raises questions about the separation of these two entities. In addition, in view of the monoclonal origin of multiple foci within the same patient, AAH may not be a precursor of AC in some cases, but rather may represent intraepithelial spread.

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.

Pulmonary preinvasive neoplasia

Advances in molecular biology have increased our knowledge of the biology of preneoplastic lesions in the human lung. The recently published WHO lung tumour classification defines three separate lesions that are regarded as preinvasive neoplasia. These are (1) squamous dysplasia and carcinoma in situ (SD/CIS), (2) atypical adenomatous hyperplasia (AAH), and (3) diffuse idiopathic pulmonary neuroendocrine cell hyperplasia (DIP-NECH). SD/CIS is graded in four stages (mild, moderate, severe, and CIS), based upon the distribution of atypical cells and mitotic figures. Most airways showing SD/CIS demonstrate a range of grades; many epithelia are hard to assess and the reproducibility of this complex system remains to be established. Detailed criteria are, however, welcome and provide an objective framework on which to compare various molecular changes. Alterations in gene expression and chromosome structure known to be associated with malignant transformation can be demonstrated in CIS, less so in dysplasias, but also in morphologically normal epithelium. The changes might be sequential, and their frequency and number increase with atypia. Less is known of the "risk of progression" of SD/CIS to invasive "central" bronchial carcinoma. It may take between one and 10 years for invasion to occur, yet the lesion(s) may be reversible if carcinogen exposure ceases. AAH may be an important precursor lesion for peripheral "parenchymal" adenocarcinoma of the lung: the "adenoma" in an adenoma-carcinoma sequence. There is good morphological evidence that AAH may progress from low to high grade to bronchioloalveolar carcinoma (BAC; a non-invasive lesion by definition). Invasion then develops within BAC and peripheral lung adenocarcinoma evolves. The molecular events associated with this progression are not well understood and studies are hampered by a lack of clear criteria to distinguish high grade AAH from BAC. Nonetheless, as with SD/CIS, the patterns of expression of tumour associated genes are consistent with neoplastic progression. We have little idea of the incidence of AAH in the normal or "smoking" populations. It is found more frequently in cancer bearing lungs, especially in those with adenocarcinoma, and is more common in women. No data are available on the risk of progression of AAH. DIPNECH is an exceptionally rare lesion associated with the development of multiple carcinoid tumours. Almost nothing is known of its biology. Knowledge of these lesions will be crucial in the design and understanding of lung cancer screening programmes, where it is likely that the morphological and, more importantly perhaps, the molecular characteristics of these lesions will provide useful targets for detection and possibly even treatment.

The association between atypical adenomatous hyperplasia and primary lung cancer

Atypical adenomatous hyperplasia (AAH) has been suggested as the adenoma in an adenoma-carcinoma sequence in the lung periphery. From 1989-1998, we undertook a systematic, prospective search for AAH in lungs resected for cancer. AAH was found in 67 of 554 patients (12. 1%) with primary lung carcinoma (9.2% in male patients and 19.0% in females). AAH was found in lungs bearing adenocarcinoma (23.2%) more frequently than with large cell undifferentiated carcinoma (12.5%) or squamous carcinoma (3.3%). A greater percentage of females with adenocarcinoma had AAH (30.2%) than did males with adenocarcinoma (18.8%). Numbers of AAH ranged from 1-42 per patient and more patients had small numbers of AAH, although 12 patients had 6 or more AAH foci. Larger numbers of AAH tended to be found in adenocarcinoma-bearing lungs. Ten of the 67 patients with AAH and primary lung carcinoma (15%) had multiple primary cancers (range 2-6), all of which were adenocarcinoma. Synchronous cancers were rare in lung tumour-bearing resections without AAH. Patients with AAH show no difference in post-operative survival to those without, for all stages of carcinoma and for Stage I disease alone. This study provides evidence for a strong association between atypical adenomatous hyperplasia and primary lung adenocarcinoma and lends weight to the AAH/adenoma-carcinoma hypothesis.