Matthew Callister

BM BCh MA PhD

Leeds Teaching Hospitals NHS Trust

Consultant Respiratory Physician (Pulmonologist)

PLCO (Learn more about this study)

PLCO-39

Jul 9, 2013

Comparison of rates of radiological imaging in control arm of PLCO vs UK population

Lung cancer outcomes in the UK lag behind other developed nations, with five year survival rates of 9% compared to 16-18% in Canada and Australia (ICBP) and 15% in the US (SEER database). The explanation for this poorer outcome is likely to be multi-factorial, but recent data has suggested that a smaller proportion of patients are diagnosed with stage I disease in the UK compared to Canada and Sweden. The UK National Awareness and Early Diagnosis Initiative has been established to try to improve earlier diagnosis of cancer, and a number of projects have attempted to increase community referral for CXR. Whilst most initiatives have sought to increase referral for CXR in response to symptoms, recent studies have demonstrated poor predictive value of respiratory symptoms for lung cancer compared to age and smoking history. By concentrating more on the latter, efforts to increase CXR referrals tend to move towards detecting asymptomatic disease in high risk populations (in effect screening) rather than early symptomatic detection although the boundaries between these approaches in clinical practice are sometimes blurred.

The PLCO study assessed the effect of CXR screening on lung cancer mortality in a North American population. CXR screening resulted in only a small increase in the proportion of patients presenting with stage I disease (27.1% in control population compared to 31.7% in screened population) and no effect on lung cancer mortality. In comparison, NLST reported a larger increase in stage I disease seen with CT screening (50.0% in CT screened population vs 31.1% in CXR screened population) and a 20% reduction in lung cancer mortality. Given that some UK early diagnosis initiatives are seeking to increase referral for CXR even in the absence of respiratory symptoms, the relevance of the PLCO findings to the UK population needs to be established.

The proportion of patients diagnosed with lung cancer who present with early stage disease is much smaller in the UK population than in the control arm of PLCO (13.5% with stage I disease in UK ICBP vs 27.1% in PLCO control). The reasons for this difference are unclear, but may relate to different background levels of radiological investigation in the population at large (CXR or CT), and are likely to lead to worse survival in UK patients compared to those in the control arm of PLCO. Leeds Teaching Hospitals (LTH) serves the city of Leeds (North England, population 770,000) and sees the largest number of new lung cancer diagnoses of any single hospital in the UK (610 in 2012). A comprehensive database has been established of both lung cancer patient characteristics and outcomes, and of CXR usage in the general population of the city. The UK National Lung Cancer Audit records information about an estimated 98% of cases of lung cancer diagnosed per year. Similarly the recently established NHS Diagnostic Imaging Dataset records information on all radiological tests undertaken including chest X-ray.