Background Computerised Tomography (CT) has been shown to be the only lung cancer screening modality to be effective in reducing lung cancer specific mortality.¹ A minimally invasive technique to stratify those at greatest risk within the population of adult smokers may help to target CT screening more effectively.

Rationale Tobacco smoke exposure causes a field of injury to the airways (including nose and mouth) that if detected may inform an individual’s risk of lung cancer.² Infrared spectroscopy (IR) is a technique that can detect subtle biochemical alterations in macroscopically normal cells.

Methods Buccal cells were exfoliated from 76 patients including 38 smokers without and 38 with lung cancer (matched for age, gender and pack years). The cells were fixed onto IR windows and spectra recorded using synchrotron radiation (Diamond facility, Oxford). Data was acquired using x36 objective and 15 × 15 µm aperture in transmission mode; 256 interferograms at 4 cm^-1 resolution were recorded for 50 cells per sample. All samples analysed were confirmed to be cytologically normal. Outlying data was removed using principal component analysis and a prediction model built using partial least squares discriminant analysis.

Results Smokers with lung cancer could be differentiated from matched smokers without lung cancer with a diagnostic accuracy of 80%. The spectral region showing greatest difference between groups was in the 1200–900 cm^-1 region; comparison to reference spectra shows that this is likely to represent a metabolic change caused by an increased abundance of glycogen or its derivatives.

Conclusions We have shown for the first time that IR spectroscopy of macroscopically normal upper respiratory tract cells may have a role to play in the early detection of lung cancer. Future work will validate these findings and aim to develop this non-invasive test for use as a pre-screen to select those at greatest risk who may be enrolled economically into surveillance programs.

References

1. The National Lung Screening Trial Research Team. Reduced lung-cancer mortality with low-dose computed tomographic screening. N Engl Med 2011;365(5):395–409

2. Sridhar et al. Smoking-induced gene expression changes in the bronchial airway are reflected in nasal and buccal epithelium. BMC Genomics 2008;9(1):259