Role of CT guided fine needle aspiration biopsy in the diagnosis of suspected lung cancer

Shiv Kumar¹, Priakshi Baruah^2*

Abstract              Problem Statement: Diagnosing lung cancer in its earlier stages has always been a challenging entity for physicians, surgeons and radiologists alike. Though FNAB has an established role in diagnosing lung cancer, the present study was conducted to evaluate the role of this modality, which is cost effective and at the same time, less time consuming. Methods: With the initial aim of diagnosing patients with suspected lung cancer, the present study, was carries out on 40 patients over a period of almost 2 years: from April 2014 to March 2016. Selection of patients was done from patients attending the Department of TB and Chest and biopsy was done in the department of Pathology in M.G.M Medical College and L.S.K. Hospital. Kishanganj, Bihar. The subjects are of varying ages and of both sexes. Relevant investigations along with a chest skiagram were done prior to undergoing a CT scan of the thorax. The present study employed the computerized software Inbuilt GE Sytec-4000 with CT equipment for CT evaluation of lung cancer. Results: A total of 31 males and 9 females suspected of having lung cancer were evaluated using CT guided FNAB. The male: female ratio was 3:4:1. The age range of both sexes was 16-70years. The age distribution is either sex revealed maximum number of patients belonging to 45-60 years. According to the age and sex distribution, the prevalence of lung cancer is more in male as compare to female, being more in middle and elderly age group, as seen in our study. Site of the lesion were recorded in all the patients included in the study of which 17 (42.5%) were hilar/mediastinal, 4 (10%) central, 13 (32.5%) peripheral and bot (central and peripheral or extensive were 6 (15%). 13 patients having squamous cell carcinoma were obtained by histopathological examination, among whom 2 had hilar (15.38%), 7 had central (53.84%), 2 had peripheral (13.38%) and 2 had extensive (15.38%) lesions. 8 patients having adenocarcinoma were obtained by histopathological examination, among whom 1 had central (12.5%), 4 had peripheral (50%) and 3 had extensive (37.5%) lesions. Conclusion: Most of the patients with lung cancer were above 40 years of age, with positive history of smoking and male predominance. Out of the 40 patients included in the study, the most common symptoms among patients with Bronchogenic carcinoma were cough (75%) chest pain (55%) haemoptysis (42.5%) and dyspnea (37.5%). So, in the present study we found that CT guided FNAB is most commonly used now-a-days to diagnose suspected lung cancer with high degree of accuracy and less chances of complication. The technique is safe, and minimally invasive as compared to other hazardous surgical procedures like open lung biopsy, thoracoscopy and bronchoscopy.

Key Word: FNAB, Lung Cancer, Adenocarcinoma, Bronchogenic carcinoma.

INTRODUCTION

The earliest reference to Bronchogenic carcinoma appears to come from Schneeberg, Saxony in 1400’s, where miners working in coal mines suffered from a diseases called “Bergususcht’ which literally means ‘disease of the mountain’. It was attributed to prolonged exposure to uranium in coal mines. This disease was later called as ‘Bronchogenic carcinoma’. Centuries later, bronchogenic carcinoma still remains ‘a disease of the mountain’. It is the most frequently diagnosed cancer in the world and leading cause of death in cancer. In USA alone since 1950 lung cancer mortality had risen by 197% in men and 612% in women. The Indian scenario does not lag anywhere behind the world statistics. As per the cancer statistics, 2005 of the United states, a total of 1,372,910 new cancer cases and 570,280 deaths are expected in 2005. The Indian National Cancer Registry Programme data evaluation from six different parts of the country ranked trachea, bronchus and lung malignancy as the most common in Bombay, Delhi and Bhopal, the third most common in Bangalore, and the seventh most common in Madras. Despite this enormous prevalence of this disease, the present scenario of this malignancy can be summarized as being the most lethal of all cancers, the most commonly detected cancer, having late clinical presentation, with no effective screening programme, though it is universally accepted to be curable only if detected in early stages, making it one of the most frustrating yet important challenge medicine is facing today. In the past, developing countries like India had limited diagnostic modalities for pulmonary masses, with such a low specific diagnostic yield that the clinicians had essentially two choices: either to recommend diagnostic thoracotomy, or to observe, usually by requesting repeated chest X-rays.   Now, with the advent of CT scan and new modalities like fine needle aspiration biopsy in the gap between the two extremes of only observation at one end and instant thoracotomy at the other has been filled, on account of a high level of confidence of the modality in the triage of intrathoracic mass lesions.         The present study was therefore undertaken with the basic aim of diagnosing patients with suspected bronchogenic carcinoma by providing a correct histopathological diagnosis with the modality which is easily available, less time consuming, minimally invasive and yet can established the diagnosis in an effective manner and at the same time evaluate the diagnostic efficacy of the new modality, in this context, the fine needle aspiration biopsy.

METHODS

With the initial aim of diagnosing patients with suspected lung cancer, the present study, was carries out on 40 patients over a period of almost 2 years: from April 2014 to March 2016. Selection of patients was done from patients attending the Department of TB and Chest and biopsy was done in the department of Pathology in M.G.M Medical College and L.S.K. Hospital. Kishanganj, Bihar. The subjects are of varying ages and of both sexes. Relevant investigations along with a chest skiagram were done prior to undergoing a CT scan of the thorax. The present study employed the computerized software Inbuit GE Sytec-4000 with CT equipment for CT evaluation of lung cancer.

RESULTS

A total of 40 patients with intrathoracic masses suspected of lung cancer attending the Department of TB and Chest Diseases, M.G.M. Medical College and L.S.K. Hospital, Kishanganj, Bihar. were evaluated. They underwent a diagnostic modality with the primary objective to provide a possible histopathological diagnosis. A total of 31 males and 9 females suspected of having lung cancer were evaluated using CT guided FNAB. The male: female ratio was 3:4:1. The age range of both sexes was 16-70years. The age distribution is either sex revealed maximum number of patients belonging to 45-60 years.

Table 1: Intrathoracic masses: age and sex distribution

According to the age and sex distribution, the prevalence of lung cancer is more in male as compare to female, being more in middle and elderly age group, as seen in our study (Table 1.).

DISCUSSION

A total number of 40 patients with intrathoracic masses suspected of lung cancer, who presented in the Department of TB and chest Diseases, Banaras Hindu University, were evaluated and underwent diagnostic modality with the primary objective to provide a possible histopathological diagnosis.         A total of 31 males and 9 females who were suspected of lung cancer were evaluated suing CT guided FNAB. The male: female ratio was 3:4:1. The age range in both sexes was 16-70 years. The age distribution in either sex revealed maximum number of patients belonging to 45-60 years. Diagnosing lung cancer in its earlier stages has always been a challenging entity for physicians, surgeons and radiologists alike. Though FNAB has an established role in diagnosing lung cancer, the present study was conducted to evaluate the role of this modality, which is cost effective and at the same time, less time consuming.

27 out of 40 patients were finally diagnosed as having lung cancer and most of them were males (77.5%) with a history of smoking. Lung cancer is most com on above 40 years of age. This statement agrees with the figures stated in Carcinoma: Cancer Journal of Clinicians, 2005. Majority of the cases of lung cancer in our study had lesions measuring >6 cm. The size of the lesion was obtained by measuring its maximum dimension of a chest X-ray. Majority of the lesions of >6 cm in size were finally shown to be malignant. Yet, malignancy was also found to be present in cases with lesions measuring even 2-4 cms (Zerhouni et al, 1986). Size alone is not sufficient in differentiating malignancy from benign nodules as nodules as small as 1cm can be malignant (Siegelman et al, 1964).             The lesions obtained by CT or chest X-ray was classified as smooth, lobulated or irregular bases on contour characteristics. The basis of such a classification was earlier studied by Siegelmen et (1984) And more recently by Yamashita et al 1995.               Out of 22 lesions having irregular margin 20 cases were diagnosed as bronchogenic carcinoma (90.90%) and thus a total of 50% cases were having bronchogenic carcinoma with irregular margins. Though the observed difference was statistically significant, contour in itself has poor specificity and prediction value for malignancy as many smooth marginated carcinomas do occur as seen in this study that 4 out of 12 lesions (33.33%) with smooth margins are malignant. This has been reported from time to time, and this view is supported by Siegelman et al (1986). Majority of the lesions in our study group were parenchymal (57.5%) and 42.5% being hilar or mediastinal. Attempt to classify lesion as central or peripheral was made with the basic aim of correlating the location of the lesion with histological diagnosis but due to large size of the lesions majority of them occupy both the regions. Various studies have reported the predominance of central position in cases of squamous cell carcinoma and small cell carcinoma, and peripheral location in adenocarcinoma and poorly differentiated carcinoma. However, in our study, out of the 13 cases of squamous cell carcinoma, on chest X-ray 7 lesions (53.84%) were central and 2 (15.38%) were extensive and occupy both the positions.

               Of the 8 cases diagnosed as adenocarcinoma, 4 (50%) lesions occupied peripheral position, 3 lesions (37.5%) were extensive and occupied both central and peripheral location, and 1 was centrally located (12.5%). Though the total number of cases in our study is small, the results were consistent with those of recent studies that historical predominance of adenocarcinoma in periphery and squamous cell carcinoma in the central location is now less distinct (Quinn et al, 1996). Out of the 40 patients included in the study the most common symptoms among the patient with bronchogenic carcinoma encountered were cough which was presented in 30 (75%) of the all the cases followed by chest pain which was there in 22 patients (55% of total), followed by haemoptysis which was there in 17 (42.5%) of the total cases followed by hoarseness, lymphadenopathy and clubbing. According the Henschke et al (1999). Cough, weight loss and dyspnea are the most common presenting symptoms in a patient with bronchogenic carcinoma (Henschke et al).

CT guided FNAB was performed in 40 patients by using biopsy needle of size 16, 18, 20 G. A total of 17 patients with hilar or mediastinal involvement and 27 with parenchymal involvement were sampled by using FNAB. Of the total 40 cases undergoing CT guided FNAB, none of the patients had suboptimal specimen. The specificity of the FNAB was found to be 100% in our study. Percutaneous interventional procedures using radiologic guidance where commonly performed and have become an integral part of the diagnostic and therapeutic armamentarium of radiologists. As a result of these advances, imaging guided procedures such as percutaneous biopsy has become widely accepted as being a safe, accurate and effective alternative to more invasive surgical procedure. The imaging method chosen in this study depends on multiple factors including size, location and visibility of the lesion. The patient’s medical condition, the personal performance, previous experience and skill of the radiologist, and the relative cost and availability of guidance method (Charboneau JW, 1990; Gazelle GS, 1989). The anatomic detail provided by CT enables precise planning of precutaneous access routes for biopsy. The superb spatial resolution also permits exact needle tip localization within lesions, even those smaller than 1 cm in diameter. Thus, small structures can be biopsied with a high degree of accuracy and low risk of complication (Muellar PR, van-Sohnenberg E, 1990; Sundaram M, 1982). Percutaneous biopsy often yields more efficient diagnosis and helps in treatment planning. Needle selection depends on the location of the lesion to be biopsied, the amount of tissue required for diagnosis and the individual preference and expertise of both the radiologist and pathologist.

Other considerations to be included are the patient’s size, coagulation characteristic, and lesion characteristics such as size, vascularities, and the relative safety of the planned accessing route. Biopsy needle can be divided into two types.

• Aspiration needle for retrieval of cytologic specimen
• Cutting needles: For retrieval of histologic specimen (Murphy FB, 1988)

Cutting needles are generally larger needles with the modified sharpened tip or cutting gap on the side (Hagga JR, 1994). In the total of 40 patients having lung masses in our study, all underwent CT guided FNAB by using needle size of 16, 18, 20 gauge depending upon the size of the tumour.   By using FNAB the obtained tissue was subjected to histopathological examination of the basis of which, 27 came out to be malignant (Squamous cell carcinoma 13 (48%14%), adenocarcinoma 8 (29.62%) small cell carcinoma 4 (14.81%) poorly differentiate carcinoma 2 (7.40%), and the remaining 13 patients were negative for malignancy, having other benign conditions like Tuberculoma 5 (12.5%), lymphoma 4 (10%), interstitial pneumonitis 1 (2.5%), Thymoma 1 (2.5%), bronchial adenoma 1 (2.5%) and interstitial fibrosis 1 (2.5%). The study conducted by Michal J, Wallace et al, supports the view that even lesion of 1cm or smaller can be diagnosed with high accuracy by FNAB. As far as complication associated with FNAB is concerned only 05out of 40 patients developed pneumothorax and 3 patients developed haemoptysis. According to A sinner W et al. Haemoptysis developed in 1.25 to 5% of patients following CT guided FNAB (Harrison BD, 1984). Although the incidence of pneumothorax is related to needle passing though aerated lung and increases significantly if the lesion is not abuttin the pleura (Vitulo P, Dore R, Cerveri I et al, 1996). The chances of complications may increase if the procedure takes more time. This was found in this present study when complications developed in the case when the procedure took a longer time (more than 15 minutes). To conclude, percutaneous CT guided FNAB is a safe and highly accurate procedure. In a prospective study of 1000 CT guided biopsy, a sensitivity of 91.8% and specificity of 98.9% were achieved (Welch TJ, Sheedy 1989).

CONCLUSION

Forty patients with suspected lung cancer, who were admitted in the TB and Chest Diseases Ward, M.G.M. Medical College and L.S.K. Hospital, Kishanganj, Bihar, underwent CT guided FNAB. My aim was to determine the role of this modality in the diagnosis of Bronchogenic Carcinoma and to assess its diagnostic accuracy and safety of the procedure. Most of the patients with lung cancer were above 40 years of age, with positive history of smoking and male predominance. Out of the 40 patients included in the study, the most common symptoms among patients with Bronchogenic carcinoma were cough (75%) chest pain (55%) haemoptysis (42.5%) and dyspnea (37.5%). As seen in our study, chances of chances of malignancy increase with tumor size and most of the lesions, >6 cm were malignant. The frequency of benign masses falls sharply with increasing size. However, size alone connot differtiate between a benign and malignant lesion. Contour alone has poor sensitivity and predictive value for malignancy. All pulmonary masses with irregular margins should be assessed as such lesions can be benign as well. However, in this study most of the lesions with irregular margins were malignant. In addition to morphological evaluation, CT provides additional information regarding. In addition to morphological evaluation, CT provides additional information regarding staging of the disease which increases the specificity and sensitivity of the CT diagnosis. An attempt to classify the location of lesion with the histology was unsuccessful because the majority of lesions had large size and thus occupies both the central and peripheral locations. All the 40 patients in this study underwent CT guided FNAB. This technique is a widely accepted, sate, accurate and effective alternative to more invasive surgical procedure. Its efficacy is even proved to be accurate in making a diagnosis in cases with lesions even <1cm. The chances of complications increase with lengthing the procedure time, and by using wide bore needles. Five patients developed pneumothorax and 3 developed haemoptysis. However, with better patient’s cooperation, complications are usually avoided. So, in the present study we found that CT guided FNAB is most commonly used now-a-days to diagnose suspected lung cancer with high degree of accuracy and less chances of complication. The technique is safe, and minimally invasive as compared to other hazardous surgical procedures like open lung biopsy, thoracoscopy and bronchoscopy.

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