CPET vs PFTs for lung cancer surgery: which is a better indicator of pre-surgical functional status?

<bold>Introduction</bold> Pulmonary function testing (PFT) is performed routinely to assess fitness in people awaiting lung cancer surgery. In the less fit, preoperative determination of exercise capacity is used, particularly peak oxygen consumption (PVO₂) from cardiopulmonary exercise testing (CPET). However, the association between PFTs and PVO₂ in this population is unclear. <bold>Aims</bold> To assess whether PFTs correlate with, and can predict, PVO₂ in people undergoing preoperative assessment for lung cancer surgery. <bold>Methods</bold> We analysed spirometry, gas transfer and CPET on people awaiting lung cancer resection at our tertiary cardiorespiratory centre, for a retrospective service review. We excluded submaximal tests (PFTs: ATS/ERS reproducibility criteria, CPET: RER ≥ 1.10 or ≥85% MVV). We assessed correlations using Pearson’s test, and analysed relationships between CPET and PFTs using linear regression and ROC analysis. <bold>Results</bold> A total of 101 people (48 female, 71±12 years, BMI 25±6kg/m²) were recorded. PVO₂ correlated significantly but weakly with FEV₁ (R=0.55), FVC (R=0.58), TLco (R=0.63) or Kco (R=0.39) (all P<0.01). Similarly, no strong model could be constructed to predict PVO₂ from PFTs. FEV₁ (l) demonstrated poor sensitivity (0.37), specificity (0.58) and area under the curve (0.395) in predicting whether a PVO₂ of 15ml/kg/min (the minimum to consider surgery) would be achieved during CPET. <bold>Conclusions</bold> PFTs are a poor predictor of PVO₂ in the preoperative assessment of lung cancer. More proactive use of CPET should be considered to assess fitness for surgical intervention in this population.