Bronchioloalveolar carcinoma: myths and realities in the surgical management

Imaging in Lung Cancer Staging

Lung cancer remains one of the leading causes of mortality worldwide, as well as in the United States. Clinical staging, primarily with imaging, is integral to stratify patients into groups that determine treatment options and predict survival. The eighth edition of the tumor, node, metastasis (TNM-8) staging system proposed in 2016 by the International Association for the Study of Lung Cancer remains the current standard for lung cancer staging. The system is used for all subtypes of lung cancer, including non-small cell lung cancer, small cell lung cancer, and bronchopulmonary carcinoid tumors.

Revisions to the TNM Staging of Lung Cancer: Rationale, Significance, and Clinical Application

Lung cancer remains the leading cause of cancer-related mortality worldwide. To formulate effective treatment strategies and optimize patient outcomes, accurate staging is essential. Lung cancer staging has traditionally relied on a TNM staging system, for which the International Association for the Study of Lung Cancer (IASLC) has recently proposed changes. The revised classification for this eighth edition of the TNM staging system (TNM-8) is based on detailed analysis of a new large international database of lung cancer cases assembled by the IASLC for the purposes of this project. Fundamental changes incorporated into TNM-8 include (a) modifications to the T classification on the basis of 1-cm increments in tumor size; (b) grouping of lung cancers that result in partial or complete lung atelectasis or pneumonitis; (c) grouping of tumors with involvement of a main bronchus irrespective of distance from the carina; (d) reassignment of diaphragmatic invasion in terms of T classification; (e) elimination of mediastinal pleural invasion from the T classification; and (f) subdivision of the M classification into different descriptors on the basis of the number and site of extrathoracic metastases. In response to these revisions, established stage groups have been modified, and others have been created. In addition, recommendations for classifying patterns of disease that result in multiple sites of pulmonary involvement, including multiple primary lung cancers, lung cancers with separate tumor nodules, multiple ground-glass/lepidic lesions, and consolidation, as well as recommendations for lesion measurement, are addressed. Understanding the key revisions introduced in TNM-8 allows radiologists to accurately stage patients with lung cancer and optimize therapy. ^©RSNA, 2018.

The IASLC Lung Cancer Staging Project: Background Data and Proposals for the Application of TNM Staging Rules to Lung Cancer Presenting as Multiple Nodules with Ground Glass or Lepidic Features or a Pneumonic Type of Involvement in the Forthcoming Eighth Edition of the TNM Classification

INTRODUCTION

Application of tumor, node, and metastasis (TNM) classification is difficult in patients with lung cancer presenting as multiple ground glass nodules or with diffuse pneumonic-type involvement. Clarification of how to do this is needed for the forthcoming eighth edition of TNM classification.

METHODS

A subcommittee of the International Association for the Study of Lung Cancer Staging and Prognostic Factors Committee conducted a systematic literature review to build an evidence base regarding such tumors. An iterative process that included an extended workgroup was used to develop proposals for TNM classification.

RESULTS

Patients with multiple tumors with a prominent ground glass component on imaging or lepidic component on microscopy are being seen with increasing frequency. These tumors are associated with good survival after resection and a decreased propensity for nodal and extrathoracic metastases. Diffuse pneumonic-type involvement in the lung is associated with a worse prognosis, but also with a decreased propensity for nodal and distant metastases.

CONCLUSION

For multifocal ground glass/lepidic tumors, we propose that the T category be determined by the highest T lesion, with either the number of tumors or m in parentheses to denote the multifocal nature, and that a single N and M category be used for all the lesions collectively-for example, T1a(3)N0M0 or T1b(m)N0M0. For diffuse pneumonic-type lung cancer we propose that the T category be designated by size (or T3) if in one lobe, as T4 if involving an ipsilateral different lobe, or as M1a if contralateral and that a single N and M category be used for all pulmonary areas of involvement.

Small peripheral lung adenocarcinoma: clinicopathological features and surgical treatment

The clinical use of high-resolution computed tomography (CT) has greatly advanced diagnosis of small peripheral lesions of the lung. In CT images, these lesions often exhibit ground-glass opacity (GGO). Ground-glass opacity is typical of noninvasive bronchioloalveolar carcinoma (BAC), which is characterized by a lepidic pattern of cells that line the alveoli but do not invade neighboring structures. Bronchioloalveolar carcinoma is classified as a subset of lung adenocarcinoma, but has distinct clinical and pathological features and a favorable prognosis. Most small peripheral lung lesions, including BAC, probably originate in the epithelium of the peripheral airway. As with other subsets of non-small cell lung cancer, surgical resection is a potentially curative treatment. However, it is questionable whether a lobectomy is necessary for small lesions that exhibit GGO, particularly when they are <1 cm in diameter. Although several Japanese investigators have suggested that a limited resection, including a wedge resection and a segmentectomy without nodal dissection, is an appropriate treatment for small lung adenocarcinomas, this approach should be validated by clinical trials.

Bronchioloalveolar lung cancer: ACCP evidence-based clinical practice guidelines (2nd edition)

OBJECTIVES

To review the current evidence on special issues relating to the diagnosis, imaging, prognosis, and treatment of bronchioloalveolar carcinoma (BAC).

METHODS

This guideline focuses on aspects of BAC that are unique and ways in which BAC differs importantly from other forms of non-small cell lung cancer (NSCLC). The author reviewed published literature reporting on BAC using key words "histology," "CT scans," "fluorodeoxyglucose positron emission tomography scan," "sensitivity," "specificity," "surgical resection," "sublobar resection," and "epidermal growth factor receptor tyrosine kinase inhibitor" and selected references from published review articles. Also included was a review of the 1999 World Health Organization (WHO) revised classification system for lung tumors, which established a more restrictive definition of BAC to tumors with a pure lepidic spreading pattern and no evidence of stromal, vascular, or pleural invasion.

RESULTS

With the notable exception of a lower likelihood of a positive positron emission tomography finding in the presence of BAC, staging, diagnosis, and treatment are the same as for other histologic subtypes of NSCLC, but additional treatment options that may prove to be equivalent, if not more effective, for more patients exist (eg, epidermal growth factor receptor tyrosine kinase inhibitor therapy, sublobar resection).

CONCLUSIONS

BAC is a form of adenocarcinoma with unique clinical, radiologic, and epidemiologic features. The diagnosis of BAC should be reserved for tumors that meet the WHO criteria. Additional clinical trials are needed on this population of patients, using strict definitions and enrollment criteria to allow the results to be applied to appropriate patient populations.

Controversy about Small Peripheral Lung Adenocarcinomas: How Should We Manage Them?

In recent years, the clinical use of high-resolution computed tomography has greatly advanced the diagnosis of small lesions of the peripheral lung. Such small lesions are often associated with ground-glass opacity in computed tomography findings. The noninvasive bronchioloalveolar carcinoma component with a replacement growth pattern of alveolar lining cells manifests as ground-glass opacity. Bronchioloalveolar carcinoma is classified as a subset of lung adenocarcinoma, but has a distinct clinical presentation, tumor biology, and favorable prognosis. Most small peripheral lung lesions including bronchioloalveolar carcinoma putatively originate from the peripheral airway epithelium, in which the epidermal growth factor receptor gene is frequently mutated. As with other subsets of non-small cell lung cancer, surgical resection is a potentially curative treatment. For the ground-glass opacity type of tiny lesions, particularly those less than 1 cm in their greatest dimension, the question has been raised whether lobectomy is really needed. Although several authors in Japan suggest the suitability of limited resection including segmentectomy and wedge resection without any nodal dissections for these small lung adenocarcinomas, this procedure should be validated in future clinical trials.

Tumor fluoro-2-deoxy-D-glucose avidity on positron emission tomographic scan predicts mortality in patients with early-stage pure and mixed bronchioloalveolar carcinoma

OBJECTIVE

Bronchioloalveolar carcinoma is a clinically heterogeneous subtype of non-small cell lung carcinoma that frequently has low 2-[18F]fluoro-D-glucose (FDG) uptake on positron emission tomographic scanning. We investigated whether tumor FDG avidity was associated with worse survival among patients with completely resected node-negative pure and mixed bronchioloalveolar carcinoma.

METHODS

We performed a cohort study of 36 patients who had completely resected pure and mixed bronchioloalveolar carcinoma between 1998 and 2004, who had no hilar or mediastinal lymph node metastases, and who had undergone a preoperative positron emission tomographic scan. Tumor FDG avidity was defined as a standardized uptake value of 2.5 or greater. Survival analysis was performed with a proportional hazards model.

RESULTS

Of 36 patients studied, 26 patients (72%) were alive and 10 patients (28%) were dead after a median follow-up of 31 months (interquartile range 17-41 months). Seventeen patients (47%) had FDG-avid tumors, and 19 patients (53%) had non-avid tumors. Three-year survival was 49% in the FDG-avid group and 95% in the non-avid group (P = .005). FDG avidity had a hazard ratio of death of 8.6 (95% confidence interval 1.4-244.7, P = .02) after adjusting for tumor size, the presence of multifocal bronchioloalveolar carcinoma, and the presence of histologically mixed bronchioloalveolar carcinoma.

CONCLUSIONS

Preoperative tumor FDG standardized uptake value of 2.5 or greater on positron emission tomography is a powerful predictor of long-term mortality in patients with lymph node-negative pure and mixed bronchioloalveolar carcinoma who undergo complete surgical resection. Patients with a high level of FDG uptake (standardized uptake value > or = 2.5) may benefit from adjuvant chemotherapy or more frequent clinical follow-up.

A new era for bronchioloalveolar carcinoma: current state of the art and recent advances in biologically targeted therapy

Bronchioloalveolar carcinoma is a fascinating and unusual variant of nonsmall-cell lung cancer that has a tendency towards an indolent course and to metastasize to the lung rather than distant organs. Chemotherapy has shown activity in advanced bronchioloalveolar carcinoma but response rates remain low. Epidermal growth factor receptor tyrosine kinase inhibitors have shown impressive activity against bronchioloalveolar carcinoma in trials. New data suggest that epidermal growth factor receptor mutations and gene copy number may predict subsets of patients who could most benefit from these novel agents. These new findings may point the way to a new era in which we can predict which patients will respond to epidermal growth factor receptor tyrosine kinase inhibitors and thus allow us to tailor therapy to the individual patient.

Bronchioloalveolar carcinoma: a review

Bronchioloalveolar carcinoma (BAC) is classified as a subset of lung adenocarcinoma but has a distinct clinical presentation, tumor biology, response to therapy, and prognosis compared with other subtypes of non-small-cell lung carcinoma (NSCLC). Bronchioloalveolar carcinoma disproportionately affects women, never-smokers, and Asians and is characterized by growth along alveolar septae without evidence of stromal, vascular, or pleural invasion. Although pure BAC accounts for approximately 4% of lung cancers, tumors with histologically mixed BAC and adenocarcinoma account for > 20% of all NSCLCs, and the incidence of BAC might be increasing. Bronchioloalveolar carcinoma histology is most commonly found in small lesions identified incidentally on chest radiographs or computed tomography scans and might represent a precursor lesion to invasive adenocarcinoma. As with other subsets of NSCLC, surgical resection is the only potentially curative treatment. Patients with unresectable BAC are more likely to respond to the epidermal growth factor receptor tyrosine kinase inhibitors gefitinib and erlotinib than patients with other subtypes of NSCLC. Stage for stage, patients with BAC have a higher rate of long-term survival but might have an increased rate of intrathoracic recurrence than patients with other subtypes of NSCLC.

Poor results after surgery for bronchioloalveolar carcinoma

BACKGROUND

Bronchioloalveolar carcinoma (BAC) is suggested to be less aggressive than other types of lung cancer. To assess the option of treatment modification, actual outcome data were studied and compared with results for other types of lung cancer.

METHOD

Retrospective analysis of all consecutive patients who underwent resection for stage I lung cancer in our hospital. For 18 BAC cases, histological specimens were re-evaluated and in three cases diagnosis was revised.

RESULTS

In the period 1989 through 2000, 15 patients with BAC and 260 patients with other tumour types underwent surgery in our hospital. Five-year survival rates were 24 and 53%, respectively, (p = 0.01).

CONCLUSIONS

Given the poor results after standard surgery, parenchyma-sparing operations do not seem justified in patients with invasive BAC.

Cystic Bronchioloalveolar Cell Carcinoma

Bronchioloalveolar cell carcinomas (BACs), a subset of primary lung adenocarcinomas, are uncommon. Similar to other non-small cell lung cancers, patients with BAC are usually 40-70 years of age. Distinguishing features relative to other non-small cell lung cancers include occurrence in young patients, a higher relative predominance in women, and weaker association with smoking. Histologically, they are a diverse group of malignancies that grow in a lepidic manner. Common radiologic presentations of BAC include a solitary nodule, airspace disease, and multiple nodules. Rare manifestations include cystic and cavitary disease. We report a case of a young woman with BAC that manifested as a chronic cough and bilateral air-containing opacities, initially misinterpreted as infection. Knowledge of the spectrum of radiologic manifestations of BAC and correlation with clinical history are important in suggesting the diagnosis and preventing misinterpretation.

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.