Find out more about our Academic Medical Centre and efforts in Academic Medicine
Academic Medicine Executive Committee (AM EXCO)
Find out more about what JOAM do to support AM initiatives
Find out more about the Office of Duke-NUS Affairs and Study Trip to Duke Durham
Guidelines, forms, and templates for Academic Medicine.
Pulmonary nodules are often discovered incidentally. With the five-year survival rate for surgically resected early-stage lung cancer at about 75%, early identification of malignancy through careful clinical assessment of nodule size and malignancy risk is crucial to achieving better patient outcomes.
A pulmonary nodule is defined as a small (≤ 30 mm), well-defined radiographic opacity surrounded by pulmonary parenchyma, without associated atelectasis, effusion or enlarged lymph nodes. It is a common radiologic finding, and a prevalence of 20-50% has been demonstrated in healthy adult volunteers and lung cancer screening populations.1 Pulmonary nodules are often discovered incidentally, and the incidence is expected to rise with the increased utilisation of computed tomography (CT) scans.
The differential diagnosis for pulmonary nodules is broad, and includes malignancy, inflammatory, infectious, congenital, and vascular pathologies. Most (> 95%) incidental pulmonary nodules are benign, even in lung cancer screening populations, but some may be a sign of early lung cancer.2
While the overall survival rate of lung cancer remains poor (10-15% five-year survival rate), in contrast, the five-year survival rate of surgically resected early-stage lung cancer approaches 75%.
It is therefore important for managing physicians to assess the likelihood of malignancy to guide evaluation and management.
The size and morphology of the nodule are the two main determinants of cancer risk.3
Size
Nodules less than 6 mm in diameter have a low risk of cancer (< 1%), while approximately 40-80% of nodules larger than 20 mm are malignant.3
Morphology
Morphology refers to the margins (smooth, lobulated, or spiculated) and attenuation of the nodule.
Attenuation can be classified into solid or subsolid nodules, with the latter divided into pure ground glass and part-solid (having both ground glass and solid components) nodules. Ground glass nodules are characterised by an area of increased pulmonary attenuation that does not obscure underlying bronchial and vascular markings.
Subsolid or spiculated/lobulated nodules, upper lobe location as well as older age and heavy smoking also increase the risk of cancer.1,4
Quantitative assessment models have been developed to estimate the probability of malignancy, but these have not been validated in Asian populations.5
When a nodule is identified, it is important to check previous imaging studies to evaluate if the nodule is new, old, stable, or growing over time. Solid nodules that are stable over time (≥ 2 years) are unlikely to be malignant.
Management of pulmonary nodules are largely determined by:6
Not all incidental pulmonary nodules require routine follow-up or further evaluation. In a patient with a low risk profile and a solid nodule of < 6 mm, no follow-up may be necessary if this is consistent with the patient's preferences (after understanding the risks and benefits). For pulmonary nodules that require follow-up, surveillance with serial low-dose chest computed tomography scans (LDCT) is generally recommended for nodules ≤ 8 mm in diameter, or when the clinical probability of malignancy is deemed to be low (< 5%).6,7
For indeterminate nodules greater than 8 mm in size, management options can vary, including:
The management strategy will be largely guided by malignancy risk and individualised according to patient values and preferences.6 For example, non-surgical biopsy, or surgical biopsy (and possibly simultaneous resection) in an individual with low surgical risk, is typically offered when the clinical probability of malignancy is deemed to be high (> 60%).
Chest CT with thin (≤ 1 mm) sections has a higher accuracy than chest radiographs in detecting nodules and can provide information on location, size, attenuation, and characteristics of the nodule. In an individual with an indeterminate nodule identified on chest radiography, a chest CT should be performed to help characterise the nodule.4
For surveillance imaging, contrast enhancement is typically not required, and a LDCT is sufficient.
There are important considerations with risk assessment and management in the local population. Firstly, pulmonary tuberculosis is a common disease presenting as pulmonary nodule(s) in the local and Asian population.
Like cancer, tuberculosis is more commonly found in the upper lobes and can result in a positive PET scan, which makes interpretation challenging.
Secondly, Asian women who are never-smokers are at higher risk of developing lung cancer compared with women living in Western countries. Adapting risk assessment and management of patients with the above considerations in mind is recommended in our local population.6
An optional LDCT at 12 months may be performed for individuals with solid nodules < 6 mm, which should be guided by clinical assessment of malignancy risk and patient preferences.7 However, individuals with solid nodule(s) ≥ 6 mm or subsolid nodule(s) of any size should be referred to a specialist centre for management.
Organisations like the United States Preventive Services Task Force recommend annual lung cancer screening with LDCT for eligible individuals. This is largely driven by the results of large multicentre trials from North America and Europe reporting a reduction in lung cancer-related mortality with LDCT screening.8,9
Screening in Asian population However, strong evidence supporting lung cancer screening for the Asian population is still lacking, with concerns of overdiagnosis and false positives leading to unnecessary investigations (e.g., lung biopsy) with risk of complications. The ideal screening population is also unclear as a significantly higher proportion of lung cancers are detected among never-smokers in the Asian population, compared to Western countries.
Clinical practice guidelines (2010) from the Ministry of Health Singapore recommend against routine screening for lung cancer.10
Who should be screened For asymptomatic individuals between 55-74 years of age and a smoking history ≥ 30 pack-years (current smoker or ex-smoker who quit smoking within the last 15 years), it may be reasonable to engage in opportunistic discussion on lung cancer screening.11 Certainly, all patients who are current smokers should be routinely counselled on smoking cessation.
The SingHealth Duke-NUS Lung Centre is focused on delivering high quality clinical care for all thoracic conditions and provides a unique platform for multidisciplinary collaboration and consultation.
Within the Centre is a dedicated Nodule Clinic, which offers access to multidisciplinary services (by Respiratory Medicine Physicians, Surgeons, Radiologists, Oncologists and Thoracic Nurse Practitioners) as recommended in guidelines.6
Dr Goh Junyang Ken is a Consultant at the Department of Respiratory & Critical Care Medicine, Singapore General Hospital. He graduated from Duke-NUS Medical School in 2012 and obtained his specialist accreditation in Respiratory Medicine in 2018.
Dr Chai Hui Zhong obtained her medical degree from the National University of Singapore in 2012. She obtained specialist accreditation in Respiratory Medicine and Intensive Care Medicine in 2018 and 2020 respectively. Her sub-specialty interests are Chronic Mechanical Ventilation and Intensive Care Medicine. Currently, she is the Director of the Pulmonary Function Laboratory. Besides her clinical work, she is also actively involved in medical education and the use of simulation as a teaching tool.GPs can call the SingHealth Duke-NUS Lung Centre for appointments at the following hotlines, or scan the QR code for more information: Singapore General Hospital: 6326 6060Changi General Hospital: 6788 3003 Sengkang General Hospital: 6930 6000KK Women’s and Children’s Hospital: 6692 2984National Cancer Centre Singapore: 6436 8288
Tags: Lungs
Tags: