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Interact CardioVasc Thorac Surg 2005;4:18-20. doi:10.1510/icvts.2004.091843 © 2005 European Association of Cardio-Thoracic Surgery
Solitary pulmonary nodules: pathological outcome of 150 consecutively resected lesionsDepartment of Cardiothoracic Surgery, Chesterman Wing, Northern General Hospital, Sheffield S5 7AU, UK *Corresponding author. Tel.: +44-121-6326577; fax: +44-1628-829849. E-mail address: ben_davies{at}doctors.org.uk (B. Davies). Received 28 May 2004; received in revised form 21 September 2004; accepted 23 September 2004
We investigated the pathological outcome of lung resections undertaken for solitary pulmonary nodules (SPNs) <30 mm in diameter in a regional thoracic practice serving a population historically engaged in heavy and light industry together with high tobacco use. Analysis of data collected prospectively on patients undergoing open lung resection between 1998 and 2003 for SPNs <30 mm in diameter. Demographics, operative and pathological details were sought from files and electronic records. One hundred and fifty patients (80 men), underwent lung resection during the study period. Mean age at resection was 64.7 years. Mean nodule diameter was 17.6 mm as measured by CT. Eighty-seven lobectomies, nine bilobectomies, 51 wedge excisions and one pneumonectomy were performed via open approaches. Frozen section was used selectively and anatomical resection performed where feasible. Malignancy was identified in 115 patients (77.7%): 97 (65.5%) with primary lung pathology; 18 (12.2%) had metastatic deposits; 30 (20.3%) were benign. There was no significant correlation between nodule size and malignancy risk (P>0.05). An appreciation of cancer risk is crucial to the informed counselling and intelligent management of patients presenting with lung masses. In this cohort 78% of the SPNs proved to be malignant, a higher figure than other workers have previously been described.
Key Words: Solitary pulmonary nodule; Lung cancer; Lung resection
Solitary pulmonary nodules are defined as approximately round lesions less than 30 mm in diameter and completely surrounded by lung parenchyma. Such nodules are noted on 0.09–0.20% of all chest radiographs [1,2]. Causes are many and varied, including both benign and malignant conditions. The probability of the latter is influenced by an individual's risk factors such as nodule size and characteristics, patient age and smoking status. The incidence of malignancy in such nodules ranges from 10 to 70% [3,4], and their management remains a matter of debate. The challenge remains to resect malignant SPNs appropriately an in a timely fashion, yielding 5-year survival rates of 40–80% [5], whilst avoiding thoracotomy and its attendant morbidity in benign disease. A range of imaging modalities can be employed for their further investigation. At its simplest, a chest radiograph (CXR) gives information regarding size, margin characteristics, calcification and growth rate. Stable findings have classically been considered indicative of a lesion's benign nature. Today, high-resolution computed tomography (CT) scanning allows further characterisation. Several philosophies can be employed in the management of such nodules. The current management protocol, which is to be adopted in the UK following the LUCAS screening study, is to biopsy for lesions greater than 10 mm in maximum diameter or 5–10 mm lesions, which increase in size on repeated screening. With this in mind, we sought to retrospectively investigate the pathology, investigations and treatment decisions in a cohort of patients from post-industrial South Yorkshire, where historically large proportions of the population have been engaged in heavy and light industry together with high cigarette-smoking rates of 28–29% of working age men and women [6].
Adult patients undergoing lung resection for SPNs over a 5 year period from April 1998 to April 2003 were identified using the unit's computer database of prospectively collected data. Patient, operative and pathological details were then sought from original case notes and electronic records. During the study period, one hundred and fifty patients with solitary pulmonary nodules were assessed and discussed at multi-disciplinary meetings in the presence of a surgeon, radiologist, medical oncologist and respiratory physician. Formal staging was agreed by all and a consensus reached for each patient's further management. Tissue diagnosis was sought in all patients; where surgical resection was not feasible, CT-guided fine-needle aspiration cytology (FNAC) was used selectively. It is our practice to use PET scanning only in cases of diagnostic uncertainty and this approach was not employed in this cohort which by definition encompasses stage I and II cancers. Our restriction with PET scanning was due to the unavailability of the equipment in our unit. Of this group, 80 were males and 70 females. The mean age at resection was 64.7 years overall, 63.1 years for males and 65.8 years for females (see Table 1).
Eighty-seven lobectomies, nine bilobectomies, fifty-one limited resections and one pneumonectomy were performed. Pathological and radiological records were identified in 150 cases. Four patients underwent CT-guided FNAC and subsequent surgical resection. Data were incomplete for three cases. Malignant processes were identified in 115 patients (77.7%), 97 (65.5%) with primary lung pathology and 18 (12.2%) with metastatic deposits from elsewhere. Thirty (20.3%) had benign disease processes (Table 2, Chart 1). Fifty-eight patients had an initial VATS wedge resection and frozen section analysis. Once malignancy was confirmed, they were converted to a full thoracotomy for formal lobectomy and lymph node dissection.
Of the primary malignancies, adenocarcinoma was the commonest (n=51, 35%), followed by squamous (n=21, 14%) and carcinoid (n=11.7%). Pathological stage of resected primary lung malignancy is shown in Table 3. An isolated T2 small-cell lesion was downgraded to T0 following neoadjuvant therapy. For the purposes of this study this case was excluded. In a further nine pathological staging information was incomplete.
Mean nodule size of all nodules was 17.6±5.28, median 18 mm, range 5–30 mm. Mean diameters of benign and malignant nodules were 17.7 mm and 20.6 mm, respectively (Table 4); there was no significant correlation between size and risk of malignancy in our group of patients. One year stage-specific survival was 95 and 93% for Stage I and Stage II, respectively. At five years there were 54 and 13 survivors in this stage I and II cohorts (Table 5).
3.1. Postoperative morbidity and mortality There were two inpatient deaths, one peri-operatively due to uncontrollable bleeding and a second due to myocardial infarction 4 days following a lobectomy in a patient with an extensive history of ischaemic heart disease.
In our study, we chose to look at SPNs, a definable subgroup identified on the basis of CT and pathological sizing. In this cohort 78% of all SPNs, irrespective of size, were malignant. This represents a higher figure than other workers who have previously described rates of malignancy varying between 10 and 70%. Currently no guidelines provide comprehensive advice for this group [7]. Bayesian risk models [8] and multivariate logistic regression models [9] incorporating age, smoking status, nodular size and CT characteristics such as size, growth rate, marginal and calcification details have attempted to provide estimates of cancer probability and stratification into at-risk groups. When judged to be of low risk, some advocate follow-up with serial high-resolution CT examinations. There is a paucity of evidence to guide optimal frequency of follow-up. However, high-risk groups may be counselled to progress directly to surgery. Uncertainty exists for how best to manage those who fall between these two extremes and such models have only been of limited success, albeit providing similar judgement to expert physicians [2]. Further imaging such as contrast-enhanced CT or PET may be employed in an attempt to clarify the situation. Schmid et al. [10] demonstrated the benefit of the latter technique in improving staging by the detection of occult extrathoracic metastases in 14% of patients who would have otherwise have been candidates for primary surgery for higher stage non-small cell lung cancer (NSCLC). Gambhir et al. [11] constructed a decision-analysis model showing that combining CT with PET for staging was often superior in terms of cost-effectiveness to conventional strategies, principally by reducing the numbers of patients ‘requiring’ surgery by 15%, saving an estimated US$91 to 2200 per patient. Whilst PET is undoubtedly of use in higher stage disease, where it may identify covert mediastinal or extrathoracic disease, it has not been shown to reduce the number of thoracotomies in those with stage I and II lung cancer. Therefore, its use and cost-effectiveness in this sub-group of patients is open to question [12]. However, ultimately, only direct sampling can provide a definitive answer. This may be achieved by transthoracic FNAC, bronchoscopy or surgical approaches. It is our institutional philosophy to employ the former in a select few where the lesion is both accessible and diagnostic uncertainty exists. The latter has the advantage of providing tissue together with the potential for cure in an adequately staged patient by allowing resection along oncological principles, patients’ fitness permitting. Eighty to one hundred percent of SPNs are eminently resectable and resection of benign nodules incurs a mortality of <1% [13], figures giving support to advocates of a primary surgical intervention. Our local experience is one of a predominantly ageing population (mean age of 64.5 years at resection) in an area formerly associated with intensive industrial activity, high rates of tobacco usage and socio-economic deprivation. The incidence of malignancy may well not be applicable to other, younger groups. It is current local practice to discuss every suspected malignancy at a weekly joint multi-disciplinary meeting involving the chest physician, radiologist, oncologist and surgeon. We did endeavour to obtain tissue diagnoses wherever possible, as evidenced by the 51 wedge resections in our cohort Fig. 1.
In conclusion, an appreciation of cancer risk is crucial to the informed counselling and intelligent management of patients presenting with lung masses. Strategies should be based on risk assessment and a fully informed discussion with the patient. In this cohort 77.7% of the SPNs proved to be malignant, representing a higher figure than other workers have previously described. Where feasible, primary surgical resection offers timely, effective diagnosis and in many, a durable long-term survival.
We thank the Department of Histopathology at the Northern General Hospital for their assistance with this work.
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Abstract
1. Introduction