THE DIAGNOSIS OF LUNG CANCER BY EXAMINATION OF SPUTUM

Sputum analysis by flow cytometry; an effective platform to analyze the lung environment

Low dose computed tomography (LDCT) is the standard of care for lung cancer screening in the United States (US). LDCT has a sensitivity of 93.8% but its specificity of 73.4% leads to potentially harmful follow-up procedures in patients without lung cancer. Thus, there is a need for additional assays with high accuracy that can be used as an adjunct to LDCT to diagnose lung cancer. Sputum is a biological fluid that can be obtained non-invasively and can be dissociated to release its cellular contents, providing a snapshot of the lung environment. We obtained sputum from current and former smokers with a 30+ pack-year smoking history and who were either confirmed to have lung cancer or at high risk of developing the disease. Dissociated sputum cells were counted, viability determined, and labeled with a panel of markers to separate leukocytes from non-leukocytes. After excluding debris and dead cells, including squamous epithelial cells, we identified reproducible population signatures and confirmed the samples’ lung origin. In addition to leukocyte and epithelial-specific fluorescent antibodies, we used the highly fluorescent meso-tetra(4-carboxyphenyl) porphyrin (TCPP), known to preferentially stain cancer (associated) cells. We looked for differences in cell characteristics, population size and fluorescence intensity that could be useful in distinguishing cancer samples from high-risk samples. We present our data demonstrating the feasibility of a flow cytometry platform to analyze sputum in a high-throughput and standardized matter for the diagnosis of lung cancer.

Role of I-scan technique in screening for lung cancer in smokers with positive sputum cytology

Background

Lung cancer has a very poor prognosis and high mortality. Positive sputum for malignant and/or atypical cells warrants the need for fibreoptic bronchoscopy. White light bronchoscopy (WLB) is usually unable to detect preinvasive lesions; therefore, autofluorescence bronchoscopy (AFB) was introduced as a gold standard for detecting such lesions. The aim of this work was to investigate the role of I-scan as a screening tool for cancer in smoker patients showing positive sputum cytology.

Results

New suspicious findings under I-scan occurred in 11 patients (36.7%). The overall sensitivity of WLB alone to diagnose malignancy is 23.3%, in contrast to an added sensitivity of 50% when I-scan was combined with white light (p value < 0.05). The specificity of I-scan could not be assessed in the absence of control cases (true negatives). No major complications or deaths occurred. Haemorrhage and bronchospasm were the commonest minor complications.

Conclusions

The addition of I-scan to the routine white light examination can increase the overall sensitivity of bronchoscopic screening in cases of sputum suspicious for malignancy if put in experienced hand. The suggested increase in procedure duration due to the combined use of I-scan and white light bronchoscopy is not associated with life-threatening complications.

Establishing the diagnosis of lung cancer: Diagnosis and management of lung cancer, 3rd ed: American College of Chest Physicians evidence-based clinical practice guidelines

BACKGROUND

Lung cancer is usually suspected in individuals who have an abnormal chest radiograph or have symptoms caused by either local or systemic effects of the tumor. The method of diagnosis of lung cancer depends on the type of lung cancer (small cell lung cancer or non-small cell lung cancer [NSCLC]), the size and location of the primary tumor, the presence of metastasis, and the overall clinical status of the patient. The objective of this study was to determine the test performance characteristics of various modalities for the diagnosis of suspected lung cancer.

METHODS

To update previous recommendations on techniques available for the initial diagnosis of lung cancer, a systematic search of the MEDLINE, Healthstar, and Cochrane Library databases covering material to July 2011 and print bibliographies was performed to identify studies comparing the results of sputum cytology, conventional bronchoscopy, flexible bronchoscopy (FB), electromagnetic navigation (EMN) bronchoscopy, radial endobronchial ultrasound (R-EBUS)-guided lung biopsy, transthoracic needle aspiration (TTNA) or biopsy, pleural fluid cytology, and pleural biopsy with histologic reference standard diagnoses among at least 50 patients with suspected lung cancer. Recommendations were developed by the writing committee, graded by a standardized method (see the article "Methodology for Development of Guidelines for Lung Cancer" in this guideline), and reviewed by all members of the Lung Cancer Guideline Panel prior to approval by the Thoracic Oncology NetWork, the Guidelines Oversight Committee, and the Board of Regents of the American College of Chest Physicians.

RESULTS

Sputum cytology is an acceptable method of establishing the diagnosis of lung cancer, with a pooled sensitivity rate of 66% and a specificity rate of 99%. However, the sensitivity of sputum cytology varies according to the location of the lung cancer. For central, endobronchial lesions, the overall sensitivity of FB for diagnosing lung cancer is 88%. The diagnostic yield of bronchoscopy decreases for peripheral lesions. Peripheral lesions &lt; 2 or &gt; 2 cm in diameter showed a sensitivity of 34% and 63%, respectively. R-EBUS and EMN are emerging technologies for the diagnosis of peripheral lung cancer, with diagnostic yields of 73% and 71%, respectively. The pooled sensitivity of TTNA for the diagnosis of lung cancer was 90%. A trend toward lower sensitivity was noted for lesions &lt; 2 cm in diameter. TTNA is associated with a higher rate of pneumothorax compared with bronchoscopic procedures. In a patient with a malignant pleural effusion, pleural fluid cytology is reported to have a mean sensitivity of about 72%. A definitive diagnosis of metastatic disease to the pleural space can be estalished with a pleural biopsy. The diagnostic yield for closed pleural biopsy ranges from 38% to 47% and from 75% to 88% for image-guided closed biopsy. Thoracoscopic biopsy of the pleura carries the highest diagnostic yield, 95% to 97%. The accuracy in differentiating between small cell and non-small cell cytology for the various diagnostic modalities was 98%, with individual studies ranging from 94% to 100%. The average false-positive and false-negative rates were 9% and 2%, respectively. Although the distinction between small cell and NSCLC by cytology appears to be accurate, NSCLCs are clinically, pathologically, and molecularly heterogeneous tumors. In the past decade, clinical trials have shown us that NSCLCs respond to different therapeutic agents based on histologic phenotypes and molecular characteristics. The physician performing diagnostic procedures on a patient suspected of having lung cancer must ensure that adequate tissue is acquired to perform accurate histologic and molecular characterization of NSCLCs.

CONCLUSIONS

The sensitivity of bronchoscopy is high for endobronchial disease and poor for peripheral lesions &lt; 2 cm in diameter. The sensitivity of TTNA is excellent for malignant disease, but TTNA has a higher rate of pneumothorax than do bronchoscopic modalities. R-EBUS and EMN bronchoscopy show potential for increasing the diagnostic yield of FB for peripheral lung cancers. Thoracoscopic biopsy of the pleura has the highest diagnostic yield for diagnosis of metastatic pleural effusion in a patient with lung cancer. Adequate tissue acquisition for histologic and molecular characterization of NSCLCs is paramount.

Sputum cytology in suspected cases of carcinoma of lung (Sputum cytology a poor man's bronchoscopy!)

Aims:

To evaluate the role of sputum cytology in the diagnostic work-up of patients with suspected lung cancer

Settings and Design:

Spontaneously produced fresh sputum was analyzed in clinically suspected cases of lung cancer.

Materials and Methods:

Spontaneously produced fresh sputum was analyzed in 36 clinically suspected cases of lung cancer. It was carried out using the “fresh pick and smear” method, which employs examination of sputum for blood-tinged, discolored or solid particles and preparation of thin and even smears from these selected portions.

Statistical Analysis Used:

Average and means.

Results:

Sensitivity of sputum cytology was 60%, which increased with an increase in the number of samples examined.

Conclusions:

Sputum cytology in suspected cases of carcinoma of lung is a useful diagnostic tool. It may be called as a poor man's bronchoscopy.

Initial Diagnosis of Lung Cancer

BACKGROUND

Lung cancer is usually suspected in individuals who have an abnormal chest radiograph finding or have symptoms caused by either local or systemic effects of the tumor. The method of diagnosis of suspected lung cancer depends on the type of lung cancer (ie, small cell lung cancer [SCLC] or non-SCLC [NSCLC]), the size and location of the primary tumor, the presence of metastasis, and the overall clinical status of the patient.

OBJECTIVES

To determine the test performance characteristics of various modalities for the diagnosis of suspected lung cancer.

METHODS

To update previous recommendations on the initial diagnosis of lung cancer, a systematic search of MEDLINE, Healthstar, and Cochrane Library databases to July 2004, and print bibliographies was performed to identify studies comparing the results of sputum cytology, bronchoscopy, transthoracic needle aspiration (TTNA), or biopsy with histologic reference standard diagnoses among at least 50 patients with suspected lung cancer. Recommendations were developed by the writing committee, graded by a standardized method, and reviewed by all members of the lung cancer panel prior to approval by the Thoracic Oncology Network, Health and Science Policy Committee, and the Board of Regents of the American College of Chest Physician.

RESULTS

Sputum cytology is an acceptable method of establishing the diagnosis of lung cancer with a pooled sensitivity rate of 0.66 and specificity rate of 0.99. However, the sensitivity of sputum cytology varies by location of the lung cancer. For central, endobronchial lesions, the overall sensitivity of flexible bronchoscopy (FB) for diagnosing lung cancer is 0.88. The diagnostic yield of bronchoscopy decreases for peripheral lesions. Peripheral lesions smaller or larger than 2 cm in diameter showed a sensitivity of 0.34 and 0.63, respectively. In recent years, endobronchial ultrasound (EBUS) has shown potential in increasing the diagnostic yield of FB while dealing with peripheral lesions without adding to the risk of the procedure. In appropriate situations, its use can be considered before moving on to more invasive tests. The pooled sensitivity for TTNA for the diagnosis of lung cancer is 0.90. A trend toward lower sensitivity was noted for lesions < 2 cm in diameter. The accuracy in differentiating between SCLC and NSCLC cytology for the various diagnostic modalities was 0.98, with individual studies ranging from 0.94 to 1.0. The average false-positive rate and FN rate were 0.09 and 0.02, respectively.

CONCLUSIONS

The sensitivity of bronchoscopy is high for the detection of endobronchial disease and poor for peripheral lesions < 2 cm in diameter. Detection of the latter can be aided with the use of EBUS in the appropriate clinical setting. The sensitivity of TTNA is excellent for malignant disease. The distinction between SCLC and NSCLC by cytology appears to be accurate.

Performance characteristics of different modalities for diagnosis of suspected lung cancer: summary of published evidence

STUDY OBJECTIVES

To determine the test performance characteristics of various modalities for the diagnosis of suspected lung cancer.

DESIGN, SETTING, AND PARTICIPANTS

A systematic search of MEDLINE, HealthStar, and Cochrane Library databases to July 2001 and print bibliographies was performed to identify studies comparing the results of sputum cytology, bronchoscopy, transthoracic needle aspirate (TTNA), or biopsy with histologic reference standard diagnoses among at least 50 patients with suspected lung cancer.

MEASUREMENT AND RESULTS

For sputum cytology, the pooled specificity was 0.99 and the pooled sensitivity was 0.66, but sensitivity was higher for central lesions than for peripheral lesions (0.71 vs 0.49, respectively). Studies on bronchoscopic procedures provided data only on diagnostic yield (sensitivity). The diagnosis of endobronchial disease by bronchoscopy in 30 studies showed the highest sensitivity for endobronchial biopsy (0.74), followed by cytobrushing (0.59) and washing (0.48). The sensitivity for all modalities combined was 0.88. Thirty studies reported on peripheral lesions. Cytobrushing demonstrated the highest sensitivity (0.52), followed by transbronchial biopsy (0.46) and BAL/washing (0.43). The overall sensitivity for all modalities was 0.69. Peripheral lesions < 2 cm or > 2 cm in diameter showed sensitivities of 0.33 and 0.62, respectively. Updating a previous meta-analysis with 19 studies revealed a pooled sensitivity of 0.90 for TTNA. A trend toward lower sensitivity was noted for lesions that were < 2 cm in diameter. The accuracy in differentiating between small cell and non-small cell cytology for the various diagnostic modalities was 0.98, with individual studies ranging from 0.94 to 1.0. The average false-positive and false-negative rates were 0.09 and 0.02, respectively.

CONCLUSIONS

The sensitivity of bronchoscopy is high for endobronchial disease and poor for peripheral lesions that are < 2 cm in diameter. The sensitivity of TTNA is excellent for malignant disease. The distinction between small cell lung cancer and non-small cell lung cancer by cytology appears to be accurate.

Predictive value of sputum cytology

A 60 year old woman non-smoker with bronchial asthma of 6 years' duration, treated with aminophylline, salbutamol, and oral corticosteroids, was admitted because of increasing dyspnoea and productive cough. On examination she was in moderate respiratory distress with inspiratory and expiratory wheezes. Her chest radiograph was interpreted as normal. Two consecutive sputum examinations requested by a junior doctor reveal "malignant" cells.

Assessment of factors influencing the result of sputum cytology in bronchial carcinoma

In a retrospective study of 377 patients with bronchial carcinoma, sputum had been reported positive or suspicious for malignant cells in 59.7%. The most important factors contributing to a positive result were the histological cell type and the site of the tumour as assessed at bronchoscopy. Significantly more positive results were obtained in epidermoid tumours and those with a visible bronchoscopic abnormality. A higher proportion of positive results also occurred in large tumours, lower lobe tumours, and those associated with collapse and consolidation. The physical condition of the patient and the presence of infection in the sputum were not important factors contributing to a negative result. Although adequate numbers of sputum samples were collected the predominant problem was the large number of unsatisfactory sputum specimens. The preparation of the sputum specimens in the laboratory is important and is also a potential source of error.

Evaluation of patients with bronchial carcinoma

Results of diagnostic procedures are presented on 259 successive patients with bronchial cancer at Päivärinne Chest Hospital during the period 1967-73. The most common tumours were epidermoid (56%), 'small cell' (20.5%) and adenocarcinoma (9.5%). In 106 patients (41%) chest radiography suggested a tumour, though bronchoscopy was normal, and in 22 cases (8.5%) the radiograph was normal but bronchoscopy revealed a tumour. In 10 (4%) both the radiological and the bronchoscopic findings were normal. A definite histopathological diagnosis was reached by bronchoscopy in 144 patients (44%), by mediastinoscopy in 14 (5%), by fine needle biopsy in 28 (11%) and operatively in 103 (40%). Using all methods of treatment prognosis was significantly better in the group that had been diagnosed by mass miniature radiography, or accidentally (29% alive) as compared with those who had symptoms of the disease (6%).

Diagnostic accuracy in lung cancer; comparison of techniques used in association with flexible fiberoptic bronchoscopy

Flexible fiberoptic bronchoscopic examination was performed 254 times in 228 patients in a prospective study to determine what specimens would give the greatest yield in the diagnosis of lung cancer. In addition, we questioned whether postbronchoscopic sputum specimens were still the most accurate method of diagnosing lung cancer, as they had been when only the rigid bronchoscope was available. Material for cytopathologic examination was obtained from bronchial brushings, bronchial biopsy, bronchial brushings in saline solution, bronchial washings, and three postbronchoscopie sputum specimens. In the latter part of the study, patients with peripheral tumors were studied with the aid of biplane fluoroscopic techniques. Bronchial brushings and bronchial biopsy each yielded the highest percentage of positive specimens (65 percent); postbronchoscopic sputum specimens were less frequently positive (40 percent). The combination of bronchial brushings and bronchial biopsies gave the optimum overall accuracy (79 percent). Bronchial washings and postbronchoscopic sputum specimens did not add significantly to diagnostic yield, and we conclude that they should no longer be part of the diagnostic procedures routinely ordered. In peripheral lesions, diagnostic accuracy was greatly enhanced in the cases where biplane fluoroscopic techniques were employed.

The early diagnosis of lung cancer

Earlier diagnosis of malignant disease in the lung may bring about improvements in the treatment. This article discusses the effects of early diagnosis on the prognosis. Cancer of the lung may be associated with other lung pathology, thus increasing the problems of diagnosis. Diagnosis depends on radiological examination, cytology of the sputum, radio-isotope lung scanning and mediastinoscopy: an account is given of how these may be used to diagnose the condition whilst it is still at an early stage and suitable for radical treatment.

The diagnosis of primary lung cancer with special reference to sputum cytology

Of 2,545 in-patients with primary lung cancer, pathological proof of the diagnosis was obtained by sputum cytology in 48%, by bronchoscopy in 32%, by biopsy from miscellaneous sites in 12%, and at thoracotomy or necropsy only in 19%. The diagnosis was made solely on clinical and radiological evidence in 8%.

One or more satisfactory specimens of sputum from 2,035 patients gave a positivity rate of 59%. When three specimens of sputum were tested the positivity rate was 69% and when four or more were tested, 85%. The maximum false positivity rate was 0·7%. Agreement between the types of malignant cells found in the sputum and in resected or necropsy specimens occurred in 84%. The pathological diagnosis was based solely on sputum cytology in 40% of the patients in whom malignant cells were found in the sputum.

The total work of the sputum laboratories was analysed for one year (1967); sputum was examined from 1,598 patients, of whom 266 (17%) had positive results.

Of 1,518 patients who had a bronchoscopy, the positivity rate was 53%, and of 524 patients with biopsies from miscellaneous sites the rate was 64%.

Sputum cytology, as practised at present, is a very valuable method of diagnosis, but its demands on time and expertise make it unsuitable for general application outside large medical centres.