18FDG-PET-CT in the follow-up of non-small cell lung cancer patients after radical radiotherapy with or without chemotherapy: an economic evaluation.

Background: The optimal follow-up strategy of non-small cell lung cancer (NSCLC) patients after curative intent therapy is still not established. In a recent prospective study with 100 patients, we showed that a FDG-PET-CT 3 months after radiotherapy (RT) could identify progression amenable for curative treatment in 2% (95% confidence interval (CI): 1-7%) of patients, who were all asymptomatic. Here, we report on the economic evaluation of this study.

Patients And Methods: A decision-analytic Markov model was developed in which the long-term cost-effectiveness of 3 follow-up strategies was modelled with different imaging methods 3 months after therapy: a PET-CT scan; a chest CT scan; and conventional follow-up with a chest X-ray. A probabilistic sensitivity analysis was performed to account for uncertainty. Because the results of the prospective study indicated that the advantage seems to be confined to asymptomatic patients, we additionally examined a strategy where a PET-CT was applied only in the subgroup of asymptomatic patients. Cost-effectiveness of the different follow-up strategies was expressed in incremental cost-effectiveness ratios (ICERs), calculating the incremental costs per quality adjusted life year (QALY) gained.

Results: Both PET-CT- and CT-based follow-up were more costly but also more effective than conventional follow-up. CT-based follow-up was only slightly more effective than conventional follow-up, resulting in an incremental cost-effectiveness ratio (ICER) of euro 264.033 per QALY gained. For PET-CT-based follow-up, the ICER was euro 69.086 per QALY gained compared to conventional follow-up. The strategy in which a PET-CT was only performed in the asymptomatic subgroup resulted in an ICER of euro 42.265 per QALY gained as opposed to conventional follow-up. With this strategy, given a ceiling ratio of euro 80.000, PET-CT-based follow-up had the highest probability of being cost-effective (73%).

Conclusions: This economic evaluation shows that a PET-CT scan 3 months after (chemo)radiotherapy with curative intent is a potentially cost-effective follow-up method, and is more cost-effective than CT alone. Applying a PET-CT scan only in asymptomatic patients is probably as effective and more cost-effective. It is worthwhile to perform additional research to reduce uncertainty regarding the decision concerning imaging in the follow-up of NSCLC.