S74 Assessing the diagnostic accuracy of the British Thoracic Society algorithm for investigation of solid pulmonary nodules

Abstract

BackgroundThe British Thoracic Society guidelines (2015) on the investigation and management of pulmonary nodules recommend the use of two risk prediction tools to assess the likelihood of malignancy in solid pulmonary nodules (Brock model following initial CT and the model described by Herder et al. following PET-CT). Management strategies are suggested on the basis of these risk assessments. The aim of this study was to assess the performance of this algorithm in patients with solid pulmonary nodules recruited from a UK teaching hospital.MethodPatients with solid pulmonary nodules (4–30 mm) were retrospectively identified from the lung cancer MDT and a nodule follow-up clinic (n = 221). All patients had a final diagnosis confirmed by histology or radiological stability on 2-year follow up.ResultsThe median age was 69 years. The prevalence of malignancy was 37.1% (29.9% primary lung cancer, 7.2% metastatic disease). 25 patients where PET-CT was recommended by the guideline but did not occur were excluded from subsequent analysis.Ten patients had nodules <5 mm and therefore would have been immediately discharged. All these nodules were benign.CT surveillance was recommended for 106 patients (37 with nodule <8 mm, 45 with malignant risk of <10% following initial CT, and 24 with malignant risk of <10% following PET-CT). 94% of these 106 patients had benign disease, 2% had primary lung cancer and 4% had metastatic disease.Surgical/non-surgical treatment was recommended for 58 patients where the malignant risk was >70% following PET-CT. 81% of these patients had primary lung cancer, 10% had metastatic disease and 9% were benign.For nodules with a malignant risk of between 10 and 70% following PET-CT, the guidelines recommend consideration of biopsy with alternatives of CT surveillance or surgical resection depending on patient preference and fitness. Of the 22 patients with nodules in this range, 36% were benign, 55% primary lung cancer and 9% metastatic disease.ConclusionThe solid nodule algorithm from the BTS guidelines shows good accuracy in discriminating benign from malignant nodules, recommending appropriate management in a high proportion of cases. Further studies should evaluate this and the other management algorithms with prospectively collected data.

EarlyCDT Lung blood test for risk classification of solid pulmonary nodules: systematic review and economic evaluation

“…We identified one study 79 that reviewed the outcomes of 211 patients with pulmonary nodules undergoing diagnosis for lung cancer. The study reported that 37 out of 211 patients had nodules of 5-8 mm in diameter, and all were referred to CT surveillance.…”

“…The Al-Ameri et al 79 study stated that CT surveillance was recommended for 106 patients out of a total sample of 211 (37 with nodule size of < 8 mm, 45 with malignant risk of < 10% following initial CT and 24 with malignant risk of < 10% following PET-CT). Across all of these groups, six had malignant tumours within 2 years of follow-up, suggesting around a 6% risk of malignancy among those referred to CT surveillance.…”

“…The Al-Ameri et al 79 study represents the best evidence on the UK population on which to base an economic model. However, it is of small size; therefore, future evidence collection efforts should focus on describing the (sub)populations of interest, including the size of the population and key characteristics that drive value, such as prevalence, diagnostic or surveillance procedures used, histology and stage distribution at diagnosis.…”

“…However, it is of small size; therefore, future evidence collection efforts should focus on describing the (sub)populations of interest, including the size of the population and key characteristics that drive value, such as prevalence, diagnostic or surveillance procedures used, histology and stage distribution at diagnosis. Given the differences between the subpopulations in the prevalence of malignancy highlighted by Al-Ameri et al, 79 future cost-effectiveness studies of EarlyCDT Lung should establish value separately for each subpopulation.…”

“…Management under current practice, and with the addition of EarlyCDT Lung critiqued in Chapter 4, Decision problem and relevance to National Institute for Health and Care Excellence Diagnostics Assessment Report scope), or unsubstantiated assumptions (such as stage distribution; see Chapter 4, Evidence linkage, and Chapter 5, Summary of the review of cost-effectiveness studies on diagnostics for lung cancer diagnosis). A single small UK study by Al-Ameri et al79 described the flow of patients through the BTS pathway (described in Chapter 3, Computerised tomography surveillance). This study suggests that more than half of patients with incidentally detected nodules present with small or low-risk nodules with a low prevalence of malignancy, and that approximately one-third present with intermediate-risk nodules and a higher prevalence of malignancy.…”