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THORACIC RADIOLOGYQuestions, Questions, Questions
Clinical Radiology (2003) 58: 853–854 doi:10.1016/S0009-9260(03)00185-5, available online at www.sciencedirect.com
Subspecialty Corner THORACIC RADIOLOGY Questions, Questions, Questions
There are currently several areas of debate occupying the minds of thoracic radiologists, both at home and abroad. The one to generate the most passion still seems a long way from resolution—namely, would using low-dose computed tomography (CT) to screen those most at risk of developing lung cancer improve their chances of cure and lengthen their lives. The basic premise is a simple one—by the time the vast majority of lung cancers are detected clinically they are too far advanced to be cured, and overall survival rates are poor, around 14%. Conversely, if when discovered the tumour is small and localized (i.e. stage 1), 5 year survival can be as high as 70% with appropriate treatment. If untreated, survival from stage 1 cancer falls to 20% or less [1]. Finding and treating these cancers early would therefore seem a good thing. That of course is, unfortunately, a simplification of a complex issue, about which there has been a great deal written recently, in both clinical and radiological journals. Some are passionately in favour of screening, some against and most undecided. For those of us still trying to make up our minds it remains a confusing picture. One reads eloquent reviews of all the potential pitfalls and problems associated with screening, such as those by Gotway and Webb [1], Patz et al. [2], Reich [3], and the Society of Thoracic Radiology (STR) [4], each demonstrating graphically the inherent biases, lead time, length time and over-diagnosis, and one can’t help but be put off. Then turn the page from the review of Patz et al. and you find the completely opposite viewpoint, put forward with unashamed fervour, and feel oneself swaying back to the side of the screeners [5]. It is accepted that CT is more sensitive than chest radiography in the detection of small tumours, and one might therefore expect that CT will serve better as a screening tool, but that too remains in doubt. A study from Jung et al. [6] discovered extrathoracic metastases in 13% of patients with what at first appeared to be resectable stage 1 disease. A further 11% went on to develop metastases at 1 year [6]. Patz et al. [7] could find no difference in survival between patients presenting with cancers of any size less than 3 cm. CT is sensitive, but is it sensitive enough? Another concern must be the low specificity of CT, and the large numbers of benign nodules that will inevitably be turned up and investigated. The truth of course is that we simply don’t know whether screening will benefit patients at an acceptable cost to society, and we can’t know until an appropriately sized trial has been done. Such a trial will surely occur, although 0009-9260/03/$30.00/0
efforts to organize a trial through the Medical Research Council (MRC) have recently stalled. Some studies have started, and some have published prevalence results. Diederich et al. [8] recently published results from screening 817 smokers or ex-smokers over 40 years of age with a 20 pack year cigarette history. They found a total of 858 pulmonary nodules needing further investigation, of which 12 were cancers, including seven of stage 1. That equates to a lung cancer prevalence of 1.3% in the total screened population, rising to 3.9% in those over 60 [8]. Another prevalence study was published in July last year from Japan by Nawa et al. [9] after low-dose CT screening of nearly 8000 employees of the Hitachi company, regardless of age or smoking history. This study revealed a total of 40 lung cancers (prevalence 0.44%) of which 35 were stage 1. Interestingly, however, 23 of these cancers were found in patients who had never smoked, and most were in women. This too raises difficult questions: would this group really have gone on to develop clinically apparent lung cancers with a preponderance in non-smoking women, and if not what would have happened to them? I’ve no doubt the debate will go on for some time yet and the outcome won’t depend purely on the provable facts, but also on the wishes and strength of feeling of the general public. Amongst all these questions one I haven’t seen asked is how do chest radiologists feel about the prospect of taking on full-scale lung cancer screening? There is no doubt that workloads across many specialties would increase should screening be made available, but even with the help of computers, it will be us interpreting the CT images, counting the nodules and missing the occasional cancer. You need only read the job section of the British Medical Journal to see the difficulty departments have attracting radiologists into breast screening—will we find the same problems waiting for us? Time, no doubt, will tell… Another topic that has engendered much debate and confusion over the years, namely the classification of interstitial lung diseases, has taken a more positive step forward recently with the publication of a consensus statement from eminent American and European physicians, pathologists and radiologists [10]. That’s not to say it’s any easier to remember, understand or explain, but at least it is accepted. Mostly [11]. As well as the full statement I would recommend Ellis and Hansell’s slightly more radiological slant in European Radiology [12]. If lung cancer screening is still some way off, what else can we find to fill the long working days? There have been several recent suggestions of little jobs we could take on. Adams et al. [13] have shown that radiological-guided pleural biopsies are more productive and as safe as blind, ward-based ones, even if the pleural thickening is 5 mm or less. Zwischenberger et al. have found that they can get
q 2003 The Royal College of Radiologists. Published by Elsevier Science Ltd. All rights reserved.
854
CLINICAL RADIOLOGY
tissue from almost anywhere in the mediastinum with a diagnostic hit rate of 78% [14]. They suggest, therefore, that CT-guided biopsy should precede mediastinoscopy in the workup of lung cancer patients and mediastinal masses. In another interesting paper on the subject of lung cancer staging, Fultz et al. [15] found that by simply extending the range of the staging CT to include the root of the neck they were able to identify supraclavicular abnormalities in 18 out of 55 lung cancer patients, of which 15 were proven to be malignant nodes by ultrasound-guided biopsy. By adding a routine ultrasound of the neck they increased their yield of malignant nodes to 17 out of the total 55 patients. On top of all this, the search goes on for smaller and smaller pulmonary arteries and any clot within them. In one recent paper Schoepf et al. [16] found 40% more subsegmental emboli using 1 mm collimation CTPA than with 3 mm. They also significantly improved inter-observer agreement, and reduced indeterminate cases with the thinner sections. How significant are sub-segmental emboli? Again a question with no clear answer. In short, there is a lot going on in the world of thoracic radiology, but where will it all end? That is perhaps the hardest question of all. M. DARBY Department of Clinical Radiology, Leeds General Infirmary, Great George Street, Leeds, West Yorkshire, UK
REFERENCES 1 Gotway MB, Webb WR. CT for lung cancer screening. Appl Radiol, 2002;31:21– 33. 2 Patz EF, Black WC, Goodman PC. CT screening for lung cancer: not ready for routine practice. Radiology, 2001;221:587–591.
3 Reich MJ. Improved survival and higher mortality. The conundrum of lung cancer screening. Chest, 2002;122:329–337. 4 Aberle DR, Gamsu G, Henschke CI, et al. A conensus statement of the Society of Thoracic Radiology. Screening for lung cancer with helical computed tomography. J Thorac Imaging, 2001;16:65–68. 5 Miettinen OS, Henschke CI. CT screening for lung cancer: coping with nihilistic recommendations. Radiology, 2001;221:592– 596. 6 Jung KJ, Lee KS, Kim H, et al. T1 lung cancer on CT: frequency of extrathoracic metastases. J Comput Assist Tomogr, 2000;24: 711 – 718. 7 Patz EF, Rossi S, Harpole DH, et al. Correlation of tumour size and survival in patients with stage 1 non-small cell lung cancer. Chest, 2000;117:1568–1571. 8 Diederich S, Wormanns D, Semik M, et al. Screening for early lung cancer with low-dose spiral CT: prevalence in 817 asymptomatic smokers. Radiology, 2002;222:773 –781. 9 Nawa T, Nakagawa T, Kusano S, et al. Lung cancer screening using low dose spiral CT. Results of baseline and 1 year follow-up studies. Chest, 2002;122:15–20. 10 American Thoracic Society/European Respiratory Society, International multidisciplinary consensus classification of the idiopathic interstitial pneumonias. Am J Respir Crit Care Med, 2002;165: 277–304. 11 Pandit-Bhalla M, Diethelm L, Ovella T, et al. Idiopathic interstitial pneumonias: an update. J Thorac Imaging, 2003;18:1–13. 12 Ellis SM, Hansell DM. Idiopathic interstitial pneumonias: imaging– pathology correlation. Eur Radiol, 2002;12:610 –626. 13 Adams RF, Gray W, Davies RJO, Gleeson FV. Percutaneous imageguided cutting needle biopsy of the pleura in the diagnosis of malignant mesothelioma. Chest, 2001;120:1798–1802. 14 Zwischenberger JB, Savage C, Alpard SK, et al. Mediastinal transthoracic needle and core lymph node biopsy. Should it replace mediastinoscopy? Chest, 2002;121:1165–1170. 15 Fultz PJ, Feins RH, Strang JG, et al. Detection and diagnosis of nonpalpable supraclavicular lymph nodes in lung cancer at CT and ultrasound. Radiology, 2002;222:245– 251. 16 Schoepf JU, Holzknecht N, Helmberger TK, et al. Subsegmental pulmonary emboli: improved detection with thin collimation multidetector row spiral CT. Radiology, 2002;222:483–490.
Subspecialty Corner THORACIC RADIOLOGY Questions, Questions, Questions
There are currently several areas of debate occupying the minds of thoracic radiologists, both at home and abroad. The one to generate the most passion still seems a long way from resolution—namely, would using low-dose computed tomography (CT) to screen those most at risk of developing lung cancer improve their chances of cure and lengthen their lives. The basic premise is a simple one—by the time the vast majority of lung cancers are detected clinically they are too far advanced to be cured, and overall survival rates are poor, around 14%. Conversely, if when discovered the tumour is small and localized (i.e. stage 1), 5 year survival can be as high as 70% with appropriate treatment. If untreated, survival from stage 1 cancer falls to 20% or less [1]. Finding and treating these cancers early would therefore seem a good thing. That of course is, unfortunately, a simplification of a complex issue, about which there has been a great deal written recently, in both clinical and radiological journals. Some are passionately in favour of screening, some against and most undecided. For those of us still trying to make up our minds it remains a confusing picture. One reads eloquent reviews of all the potential pitfalls and problems associated with screening, such as those by Gotway and Webb [1], Patz et al. [2], Reich [3], and the Society of Thoracic Radiology (STR) [4], each demonstrating graphically the inherent biases, lead time, length time and over-diagnosis, and one can’t help but be put off. Then turn the page from the review of Patz et al. and you find the completely opposite viewpoint, put forward with unashamed fervour, and feel oneself swaying back to the side of the screeners [5]. It is accepted that CT is more sensitive than chest radiography in the detection of small tumours, and one might therefore expect that CT will serve better as a screening tool, but that too remains in doubt. A study from Jung et al. [6] discovered extrathoracic metastases in 13% of patients with what at first appeared to be resectable stage 1 disease. A further 11% went on to develop metastases at 1 year [6]. Patz et al. [7] could find no difference in survival between patients presenting with cancers of any size less than 3 cm. CT is sensitive, but is it sensitive enough? Another concern must be the low specificity of CT, and the large numbers of benign nodules that will inevitably be turned up and investigated. The truth of course is that we simply don’t know whether screening will benefit patients at an acceptable cost to society, and we can’t know until an appropriately sized trial has been done. Such a trial will surely occur, although 0009-9260/03/$30.00/0
efforts to organize a trial through the Medical Research Council (MRC) have recently stalled. Some studies have started, and some have published prevalence results. Diederich et al. [8] recently published results from screening 817 smokers or ex-smokers over 40 years of age with a 20 pack year cigarette history. They found a total of 858 pulmonary nodules needing further investigation, of which 12 were cancers, including seven of stage 1. That equates to a lung cancer prevalence of 1.3% in the total screened population, rising to 3.9% in those over 60 [8]. Another prevalence study was published in July last year from Japan by Nawa et al. [9] after low-dose CT screening of nearly 8000 employees of the Hitachi company, regardless of age or smoking history. This study revealed a total of 40 lung cancers (prevalence 0.44%) of which 35 were stage 1. Interestingly, however, 23 of these cancers were found in patients who had never smoked, and most were in women. This too raises difficult questions: would this group really have gone on to develop clinically apparent lung cancers with a preponderance in non-smoking women, and if not what would have happened to them? I’ve no doubt the debate will go on for some time yet and the outcome won’t depend purely on the provable facts, but also on the wishes and strength of feeling of the general public. Amongst all these questions one I haven’t seen asked is how do chest radiologists feel about the prospect of taking on full-scale lung cancer screening? There is no doubt that workloads across many specialties would increase should screening be made available, but even with the help of computers, it will be us interpreting the CT images, counting the nodules and missing the occasional cancer. You need only read the job section of the British Medical Journal to see the difficulty departments have attracting radiologists into breast screening—will we find the same problems waiting for us? Time, no doubt, will tell… Another topic that has engendered much debate and confusion over the years, namely the classification of interstitial lung diseases, has taken a more positive step forward recently with the publication of a consensus statement from eminent American and European physicians, pathologists and radiologists [10]. That’s not to say it’s any easier to remember, understand or explain, but at least it is accepted. Mostly [11]. As well as the full statement I would recommend Ellis and Hansell’s slightly more radiological slant in European Radiology [12]. If lung cancer screening is still some way off, what else can we find to fill the long working days? There have been several recent suggestions of little jobs we could take on. Adams et al. [13] have shown that radiological-guided pleural biopsies are more productive and as safe as blind, ward-based ones, even if the pleural thickening is 5 mm or less. Zwischenberger et al. have found that they can get
q 2003 The Royal College of Radiologists. Published by Elsevier Science Ltd. All rights reserved.
854
CLINICAL RADIOLOGY
tissue from almost anywhere in the mediastinum with a diagnostic hit rate of 78% [14]. They suggest, therefore, that CT-guided biopsy should precede mediastinoscopy in the workup of lung cancer patients and mediastinal masses. In another interesting paper on the subject of lung cancer staging, Fultz et al. [15] found that by simply extending the range of the staging CT to include the root of the neck they were able to identify supraclavicular abnormalities in 18 out of 55 lung cancer patients, of which 15 were proven to be malignant nodes by ultrasound-guided biopsy. By adding a routine ultrasound of the neck they increased their yield of malignant nodes to 17 out of the total 55 patients. On top of all this, the search goes on for smaller and smaller pulmonary arteries and any clot within them. In one recent paper Schoepf et al. [16] found 40% more subsegmental emboli using 1 mm collimation CTPA than with 3 mm. They also significantly improved inter-observer agreement, and reduced indeterminate cases with the thinner sections. How significant are sub-segmental emboli? Again a question with no clear answer. In short, there is a lot going on in the world of thoracic radiology, but where will it all end? That is perhaps the hardest question of all. M. DARBY Department of Clinical Radiology, Leeds General Infirmary, Great George Street, Leeds, West Yorkshire, UK
REFERENCES 1 Gotway MB, Webb WR. CT for lung cancer screening. Appl Radiol, 2002;31:21– 33. 2 Patz EF, Black WC, Goodman PC. CT screening for lung cancer: not ready for routine practice. Radiology, 2001;221:587–591.
3 Reich MJ. Improved survival and higher mortality. The conundrum of lung cancer screening. Chest, 2002;122:329–337. 4 Aberle DR, Gamsu G, Henschke CI, et al. A conensus statement of the Society of Thoracic Radiology. Screening for lung cancer with helical computed tomography. J Thorac Imaging, 2001;16:65–68. 5 Miettinen OS, Henschke CI. CT screening for lung cancer: coping with nihilistic recommendations. Radiology, 2001;221:592– 596. 6 Jung KJ, Lee KS, Kim H, et al. T1 lung cancer on CT: frequency of extrathoracic metastases. J Comput Assist Tomogr, 2000;24: 711 – 718. 7 Patz EF, Rossi S, Harpole DH, et al. Correlation of tumour size and survival in patients with stage 1 non-small cell lung cancer. Chest, 2000;117:1568–1571. 8 Diederich S, Wormanns D, Semik M, et al. Screening for early lung cancer with low-dose spiral CT: prevalence in 817 asymptomatic smokers. Radiology, 2002;222:773 –781. 9 Nawa T, Nakagawa T, Kusano S, et al. Lung cancer screening using low dose spiral CT. Results of baseline and 1 year follow-up studies. Chest, 2002;122:15–20. 10 American Thoracic Society/European Respiratory Society, International multidisciplinary consensus classification of the idiopathic interstitial pneumonias. Am J Respir Crit Care Med, 2002;165: 277–304. 11 Pandit-Bhalla M, Diethelm L, Ovella T, et al. Idiopathic interstitial pneumonias: an update. J Thorac Imaging, 2003;18:1–13. 12 Ellis SM, Hansell DM. Idiopathic interstitial pneumonias: imaging– pathology correlation. Eur Radiol, 2002;12:610 –626. 13 Adams RF, Gray W, Davies RJO, Gleeson FV. Percutaneous imageguided cutting needle biopsy of the pleura in the diagnosis of malignant mesothelioma. Chest, 2001;120:1798–1802. 14 Zwischenberger JB, Savage C, Alpard SK, et al. Mediastinal transthoracic needle and core lymph node biopsy. Should it replace mediastinoscopy? Chest, 2002;121:1165–1170. 15 Fultz PJ, Feins RH, Strang JG, et al. Detection and diagnosis of nonpalpable supraclavicular lymph nodes in lung cancer at CT and ultrasound. Radiology, 2002;222:245– 251. 16 Schoepf JU, Holzknecht N, Helmberger TK, et al. Subsegmental pulmonary emboli: improved detection with thin collimation multidetector row spiral CT. Radiology, 2002;222:483–490.