Evaluation of intrathoracic extent of lung cancer by plain chest radiography, computed tomography, and magnetic resonance imaging

CT for Predicting the Resectability of Lung Cancer

In order to assess the accuracy of CT in predicting the resectability of lung cancer, a prospective study was performed on 96 patients undergoing thoracotomy. The tumors were classified preoperatively according to the TNM classification and the new international staging system for lung cancer, and scored as being resectable by lobectomy or pulmectomy, potentially resectable by lobectomy or pulmectomy, or nonresectable. Of the tumors predicted to be resectable or potentially resectable, 86.6% and 63% were radically resected, respectively, and the need for lobectomy versus pulmectomy was correctly estimated in 81.3% of them. The insufficiency of CT for defining lymph node metastases and infiltrative tumor growth was considered a marked disadvantage of the method.

Sex and Smoking Status Effects on the Early Detection of Early Lung Cancer in High-Risk Smokers Using an Electronic Nose

OBJECTIVE

Volatile organic compounds (VOCs) in exhaled breath as measured by electronic nose (e-nose) have utility as biomarkers to detect subjects at risk of having lung cancer in a screening setting. We hypothesize that breath analysis using an e-nose chemo-resistive sensor array could be used as a screening tool to discriminate patients diagnosed with lung cancer from high-risk smokers.

METHODS

Breath samples from 191 subjects-25 lung cancer patients and 166 high-risk smoker control subjects without cancer-were analyzed. For clinical relevancy, subjects in both groups were matched for age, sex, and smoking histories. Classification and regression trees and discriminant functions classifiers were used to recognize VOC patterns in e-nose data. Cross-validated results were used to assess classification accuracy. Repeatability and reproducibility of e-nose data were assessed by measuring subject-exhaled breath in parallel across two e-nose devices.

RESULTS

e-Nose measurements could distinguish lung cancer patients from high-risk control subjects, with a better than 80% classification accuracy. Subject sex and smoking status impacted classification as area under the curve results (ex-smoker males 0.846, ex-smoker female 0.816, current smoker male 0.745, and current smoker female 0.725) demonstrated. Two e-nose systems could be calibrated to give equivalent readings across subject-exhaled breath measured in parallel.

CONCLUSIONS

e-Nose technology may have significant utility as a noninvasive screening tool for detecting individuals at increased risk for lung cancer.

SIGNIFICANCE

The results presented further the case that VOC patterns could have real clinical utility to screen for lung cancer in the important growing ex-smoker population.

Evaluation of the influence of breathing on the movement and modeling of lung tumors

PURPOSE

Respiration causes movement and potential shape change in lung tumors that are not fully appreciated using conventional free-breathing CT models for radiotherapy planning. Although target expansion has the potential to ensure proper tumor coverage in the face of motion on a free-breathing CT scan, large variations in how individual patients' tumors move may make such expansions difficult to uniformly define. In addition, excessive expansion may result in the unnecessary inclusion of normal lung in the treated volume. This study was designed to evaluate the influence of breathing movement on tumors and to assess the validity of the free-breathing CT scan for target delineation in the lung.

METHODS AND MATERIALS

Data from 16 consecutive lung cancer patients who underwent treatment planning CT scans at inhale and exhale and during free breathing on a fast helical CT scanner were analyzed. Gross tumor volumes (GTV) were defined on each scan. A composite GTV was created by combining the inhale and exhale GTVs (COMP). Two methods of expansion were used to compare COMP to the free-breathing GTV (FREE). First the free-breathing data set was expanded uniformly by 1 cm (FREE + 1). Next, a nonuniform expansion was generated in all 6 directions to ensure complete coverage of COMP with the minimal subtended volume (FREE + EXP). The amount of excess normal lung treated with these 2 expansions was compared. The volume of the COMP missed using the 1-cm expansion was determined.

RESULTS

There was a significant amount of excess normal lung tissue treated with the uniform 1-cm (FREE + 1) expansion, as well as with the nonuniform (FREE + EXP) expansion. In addition, there were also cases where this technique led to marginal miss of the tumor, including one case where 47% of the overall tumor was missed with this 1-cm (FREE + 1) expansion. An attempt to create a systematic model for expansion was not successful. Although the mean expansions in the anterior-posterior, superior-inferior, and right-left directions were reasonable (0.9, 1.0, and 0.8 cm, respectively), the large intrapatient variations (sigma 0.6 cm anterior-posterior, 0.7 cm superior-inferior, and 0.5 cm right-left) suggest difficulty in assigning a simple rule for population target expansion. Some extension of FREE outside of the borders of COMP was observed, suggesting the need for evaluation of reproducibility over multiple breathing states.

CONCLUSIONS

Traditional methods of expanding the GTV to CTV by 1 cm are less than ideal. This method tends to include more normal lung than necessary and may lead to marginal miss. Interpatient tumor movement variations further prohibit defining a simple rule for nonuniform expansion that would minimize the volume of normal lung in the target. Although the development of target volumes by combining information from breath-hold CT scans at inhale and exhale states shows some promise in minimizing excess lung irradiated while maintaining adequate tumor coverage, further tests of breathing reproducibility need to be performed to provide a confident baseline for defining target expansions by this technique.

Preoperative evaluation of bronchogenic carcinoma: value of MR in T- and N-staging

Seventy consecutive patients with a bronchogenic carcinoma, in whom chest radiographs did not allow a sufficient evaluation of primary tumor localization or extension were examined by MR (1T). All diagnoses were confirmed by operation and histopathologic examination (Stage T1: 6 patients, Stage T2: 36 patients, Stage T3: 19 patients, Stage T4: 9 patients). T-staging was correct in 79% of patients. Significant infiltration of major bronchi, of the pericardium, heart, mediastinal fat and chest wall can be visualized with a reasonable degree of accuracy. N-staging based on lymph-node size was correct in 56%. A correlation between lymph-node size and metastatic involvement was not found. MR is limited by the spatial resolution, by the lack of tissue specificity and by artifacts. MR is a useful diagnostic tool in the evaluation of the primary tumor extension, however, especially in borderline cases histopathologic examination is required. A reliable N-staging is not possible based on lymph-node size measurement.

Imaging techniques in the evaluation of pulmonary parenchymal neoplasms

Conventional PA and lateral chest radiographs continue to be the initial examination of choice to evaluate patients who are suspected of having a pulmonary parenchymal neoplasm. A lung lesion can be characterized as probably benign or malignant based on its radiographic appearance (size, shape, margins, presence of calcification, cavitation or air bronchograms, growth rate). A spiculated or lobulated lesion greater than 3 cm in size that is noncalcified is highly suspicious for malignancy. A lung lesion less than 3 cm in size with smooth borders that appears noncalcified on conventional radiographs should be examined by CT, including densitometry to detect calcification or fat, which indicates benignity. In patients with known lung cancer, CT can help to stage the tumor by indicating hilar or mediastinal involvement, or distant metastases. Currently, MR imaging has a limited role, but can be used as a "problem solving" modality for selected cases in evaluating pulmonary parenchymal neoplasms.

Contrast-enhanced MRI for the staging of bronchogenic carcinoma: comparison with CT and histopathologic staging--preliminary results

Nineteen patients with potentially operable bronchial carcinoma were included in a prospective study to assess the staging capabilities of plain and contrast-enhanced magnetic resonance imaging (MRI) in comparison with computed tomography (CT) and to compare the results to post-operative histopathological staging (HS). The evaluation focused on the following T-staging criteria: (i) direct invasion of the pleura; (ii) neoplastic invasion of the mediastinum; (iii) differentiation of the primary tumour from alterations of the surrounding lung parenchyma such as inflammation or atelectasis; and (iv) intrathoracic lymph node involvement by tumour. MRI and CT produced similar results for pleural invasion (sensitivity of 0.4 and 0.75 respectively and a specificity of 0.86 and 0.93 respectively). Mediastinal invasion was overdiagnosed in four patients (no false negatives), whereas CT had only one false positive result (two false negatives). Our results showed CT to be superior to MRI for the preoperative evaluation of patients suffering from bronchogenic carcinoma.

Non-small cell lung cancer. Part I: Biology, diagnosis, and staging

Squamous, large cell, and adenocarcinoma, collectively termed non-small cell lung cancer (NSCLC), are diagnosed in approximately 75% of patients with lung cancer in the United States. The treatment of these three tumor cell types is approached in virtually identical fashion because, in contrast to small cell carcinoma of the lung, NSCLC more frequently presents with localized disease at the time of diagnosis and is thus more often amenable to surgical resection but less frequently responds to chemotherapy and irradiation. Cigarette smoking is etiologically related to the development of NSCLC in the great majority of cases. Genetic mutations in dominant oncogenes such as K-ras, loss of genetic material on chromosomes 3p, 11p, and 17p, and deletions or mutations in tumor suppressor genes such as rb and p53 have been documented in NSCLC tumors and tumor cell lines. NSCLC is diagnosed because of symptoms related to the primary tumor or regional or distant metastases, as an incidental finding on chest radiograph, or rarely because of a paraneoplastic syndrome such as hypercalcemia or hypertrophic pulmonary osteoarthropathy. Screening smokers with periodic chest radiographs and sputum cytologic examination has not been shown to reduce mortality. The diagnosis of NSCLC is usually established by fiberoptic bronchoscopy or percutaneous fine-needle aspiration, by biopsy of a regional or distant metastatic site, or at the time of thoracotomy. Pathologically, NSCLC arises in a setting of bronchial mucosal metaplasia and dysplasia that progressively increase over time. Squamous carcinoma more often presents as a central endobronchial lesion, while large cell and adenocarcinoma have a tendency to arise in the lung periphery and invade the pleura. Once the diagnosis is made, the extent of tumor dissemination is determined. Since most NSCLC patients who survive 5 years or longer have undergone surgical resection of their cancers, the focus of the staging process is to determine whether the patient is a candidate for thoracotomy with curative intent. The dominant prognostic factors in NSCLC are extent of tumor dissemination, ambulatory or performance status, and degree of weight loss. Stages I and II NSCLC, which are confined within the pleural reflection, are managed by surgical resection whenever possible, with approximate 5-year survival of 45% and 25%, respectively. Patients with stage IIIa cancers, in which the primary tumor has extended through the pleura or metastasized to ipsilateral or subcarinal lymph nodes, can occasionally be surgically resected but are often managed with definitive thoracic irradiation and have 5-year survival of approximately 15%.(ABSTRACT TRUNCATED AT 400 WORDS)

99mTc-anti-CEA radioimmunoscintigraphy of lung adenocarcinoma

Anti-carcinoembryonic antigen radioimmunoscintigraphy (anti-CEA RIS) in colorectal adenocarcinoma has been reported to allow a better estimation of the local tumor extension than other radiologic methods. This study evaluated the clinical feasibility of a 99mTc-labeled anti-CEA monoclonal antibody (BW 431/26, Behring Institute, FRG) in 11 patients for staging of primary adenocarcinoma of the lung. The primary tumor size ranged from 3 to 8 cm with a mean of 4 cm. Mediastinal and hilar nodes were present in four patients, intrapulmonary metastases were present in two patients, and pleural and liver metastases were present in one patient each. The CEA levels were in the range of 2 to 265 ng/ml and elevated (greater than 5 ng/ml) in six patients. Planar scintigraphy was performed at 6 h and 24 h post injection (pi). Analog and digitized images were interpreted by two observers. One patient was imaged twice and experienced serum sickness due to human anti-mouse antibodies (HAMA) after the second study, which showed marked unspecific tracer uptake in liver, spleen, and bone marrow, but no specific uptake by the tumor and was excluded from further analysis. Visual interpretation identified the primary tumor clearly in seven patients. No tumor imaging was observed in two patients. Two patients were classified as having questionable imaging due to a poor separation of tumor uptake from mediastinal blood pool. The primary tumor could be clearly delineated in both patients after comparison with the chest radiograph. Thus, the overall sensitivity for imaging of the primary tumor was 82 percent. The average target/background ratio was 1.31 +/- 0.17:1 at 6 h pi, and 1.30 +/- 0.16:1 at 24 h pi. Hilar and mediastinal nodes were correctly suspected in three patients, but the cardiac blood pool hampered a clear interpretation. Intrapulmonary and pleural metastases were diagnosed in all cases. The single liver metastasis was missed because of the high unspecific tracer uptake. Planar anti-CEA RIS with 99mTc BW 431/26 was superior to computed tomography (CT) in one case with subtotal tumor resection. We summarize that at present, planar anti-CEA RIS with 99mTc BW 431/26 cannot be advised as a routine staging procedure in adenocarcinoma of the lung, but it may be helpful in the detection of residual or recurrent tumor tissue.

Clinical staging of patients with non-small cell lung cancer

This article is the first in a planned series from the Section on Lung Cancer of the ACCP addressing the important and clinically relevant aspects of what is now the most common malignancy in the world, lung cancer. This initial report addresses the problem of staging of lung cancer. Staging, or identifying the anatomic extent of disease according to the AJCC TNM classification scheme, is the first clinical activity in caring for a patient with known or presumed lung cancer because the results determine appropriate types of therapy. This is, therefore, a critically important aspect of the patient's care which forms the foundation for subsequent treatment. In addition, consistent use of this system, based on appropriate clinical and pathologic staging, in stratifying patients in clinical reports is mandatory; otherwise, meaningful comparisons and conclusions are impossible.