The impact of decreasing cutoff values for maximal oxygen consumption (VO(2)max) in the decision-making process for candidates to lung cancer surgery.

BACKGROUND

Maximal oxygen consumption (VO(2)max) is considered a decisive test for risk prediction in patients with borderline cardiopulmonary reserve. Guidelines have adopted decreasing VO(2)max cut-off values to define operability within acceptable mortality and morbidity limits. We wanted to investigate how the adoption of decreasing VO(2)max cut-off-values assessment contributed to better select lung surgery candidates.

METHODS

One hundred and nineteen consecutive surgical candidates have been prospectively analyzed as a sample population. Preoperative work-up included spirometry and transfer factor (DLco); irrespective of the spirometric values, these patients were subjected to VO(2)max assessment. Surgical eligibility was decided by the same surgeon throughout the series. In the postoperative period, overall mortality and the occurrence of any, major or minor complications was recorded and graded according to the Common Terminology Criteria for Adverse Events v.4.3.

RESULTS

Three arbitrary cut-offs were introduced at 15, 14 and 12 mL(.)kg(-1) (.)min(-1). Notably, 15 and 12 mL(.)kg(-1) (.)min(-1) correlated with percentage VO(2)max values of 50% and 35% of predicted (P<0.0001 and 0.0079), respectively. Accordingly, the patients were subdivided into groups in which the prevalence of postoperative morbidity was recorded. The groups were homogeneous as to age, BMI, preoperative absolute and percentage FEV1 and DLco. In the Cox proportionate-hazards multivariate analysis, VO(2)max less than 35% (P=0.0017) and CTCAE >2 (P=0.0457) emerged as significant predictors of survival after surgery. Conversely on logistic regression analysis, age over 70 years (P=0.03) and pneumonectomy (P=0.001), but not VO(2)max cut-off values, were significant predictors of major (CTCAE >2) morbidity.

CONCLUSIONS

Since VO(2)max is increasingly used to contribute to risk prediction for the individual patient, surgeons need to be advised that the concept of a definitive, generalized cut-off value for VO(2)max is probably a contradiction in terms. Patient-specific VO(2)max values are more likely to contribute to risk assessment since they may reflect the primarily affected component among the determinants of maximal oxygen consumption. Whether patient-specific VO(2)max should be routinely used by surgeons to define operability for borderline patients needs further evaluation.