Highlight
- 76% of lung cancer screening participants reported at least one respiratory or red flag symptom at baseline.
- Common symptoms included cough (36%) and dyspnoea (66%), while red flag symptoms such as haemoptysis and unintentional weight loss were reported by 6%.
- Presence of any symptom was independently associated with a higher risk of lung cancer diagnosis within one year (OR 1.45, p=0.03).
- These findings call for a nuanced approach to defining ‘asymptomatic’ populations in lung cancer screening programs.
Study Background
Lung cancer remains the leading cause of cancer-related mortality worldwide, largely due to late-stage diagnosis. Early detection through screening—primarily by Low-Dose Computed Tomography (LDCT)—is an established strategy to improve prognosis. Most screening programs have traditionally targeted asymptomatic individuals at high risk, commonly defined by age and smoking history, under the premise that symptoms usually herald advanced disease. However, many symptoms of lung cancer overlap significantly with chronic respiratory conditions such as chronic obstructive pulmonary disease (COPD), which complicates the clinical classification of individuals as symptom-free. Understanding symptom prevalence and their prognostic significance within screening populations is critical to refine eligibility criteria, optimize screening outcomes, and minimize missed opportunities for earlier diagnosis.
Study Design
The SUMMIT study is a prospective observational cohort designed to assess real-world implementation of LDCT for lung cancer screening. The analysis included 13,035 participants eligible for baseline LDCT who provided detailed baseline clinical data—self-reported respiratory and red flag symptoms, medical history, demographic information, and spirometry measures. Symptoms were categorized into red flag symptoms (haemoptysis within one year and unintentional weight loss ≥5 kg over 3 months) and non-specific respiratory symptoms including cough (acute, 6 weeks) and dyspnoea measured by the modified Medical Research Council (mMRC) scale. Incident lung cancer diagnoses within one year following baseline assessment were adjudicated. Multivariable logistic regression adjusted for baseline risk factors evaluated the association between symptoms and lung cancer diagnosis.
Key Findings
The study found a high prevalence of symptoms among individuals undergoing lung cancer screening: 76% reported at least one symptom at baseline. Specifically, cough was reported by 36% and dyspnoea by 66% of participants. Red flag symptoms were relatively uncommon, reported by 6%, with haemoptysis and weight loss being the main contributors.
Notably, the presence of any symptom was independently associated with an increased likelihood of lung cancer diagnosis within one year, with an adjusted odds ratio of 1.45 (p=0.03). This moderate but statistically significant association persisted after adjusting for confounders, suggesting symptoms hold prognostic value in this population even amid frequent overlapping respiratory comorbidities.
The results emphasize that symptoms, though common, should not be overlooked in screening contexts. Instead, they may help stratify risk and prompt timely diagnostic evaluation beyond standard screening protocols focused solely on demographic and smoking history criteria.
Expert Commentary
This study challenges the conventional paradigm that lung cancer screening populations should be asymptomatic. The high prevalence of common respiratory symptoms—often linked to chronic lung diseases—underlines a complexity in defining asymptomatic screening candidates. The statistically significant increased risk of cancer diagnosis with any symptom presence supports the inclusion of symptom assessment as part of screening evaluation.
However, the moderate effect size also reflects the nonspecific nature of symptoms like cough and dyspnoea in high-risk populations, necessitating careful clinical correlation. Moreover, the rare reporting of red flag symptoms highlights their continued importance in urgent referral pathways but suggests most screening-detected cancers manifest with subtler clinical presentations.
Limitations include reliance on self-reported symptoms, which may be influenced by recall bias, and the observational design which precludes causal inference. Also, findings may not generalize to populations with different respiratory comorbidity profiles or screening strategies.
In clinical practice, integrating symptom assessment with traditional risk factors may enable more personalized screening and follow-up strategies, potentially improving early lung cancer detection while avoiding overdiagnosis.
Conclusion
The SUMMIT study demonstrates that respiratory symptoms are prevalent among lung cancer screening participants and are associated with an increased risk of lung cancer diagnosis within one year. These findings underscore the importance of re-evaluating symptom status within screening criteria rather than rigidly defining screening populations as asymptomatic. Incorporating symptom evaluation in screening protocols could enhance risk stratification and facilitate earlier diagnosis. Further studies are warranted to refine symptom-based algorithms and examine their impact on screening efficiency and patient outcomes.
Funding and Clinical Trials Registration
Details on funding sources and clinical trial registration for the SUMMIT study were not detailed in the provided abstract.
References
1. Mullin ML, et al. Symptom prevalence and impact on lung cancer risk in the SUMMIT study. Chest. 2026 Jun 30; PMID: 42379289.
2. National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl J Med. 2011;365(5):395-409.
3. Aberle DR, et al. Baseline characteristics of participants in the National Lung Screening Trial. Radiology. 2011;258(1):243-253.
4. Oudkerk M, et al. European position statement on lung cancer screening. Lancet Oncol. 2020;21(11):e150-e160.