AbstractMetachronous oligo-metastatic disease is variably defined as one to five metastases detected after a disease-free interval and treatment of the primary tumour with curative intent. Oligo-metastases in non-small cell lung cancer (NSCLC) are often treated with curative intent. However additional metastases are often detected later in time, and 5-year survival is low. Burdensome surgical treatment in patients with undetected metastases may be avoided if patients with high versus low-risk of undetected metastases can be separated.Because there is no clinical data on undetected metastases available, a microsimulation-model of the development and detection of metastases in 100.000 stage I NSCLC patients with a controlled primary tumour was constructed. The model uses data from the literature as well as patient-level data. Calibration was used for unobservable model parameters. Metastases can be detected by a scheduled scan, or an unplanned scan when the patient develops symptoms. The observable information at time of detection is used to identify subgroups of patients with different risk of undetectable metastases. We identified size and number of detected oligo-metastases, as well as presence of symptoms to be the most important risk predictors. Based on these predictors, patients could be divided into a low-risk and a high-risk group having a model-based predicted probability of 8.1% and 89.3% to have undetected metastases, respectively.Currently, the model is based on a synthesis of literature data and individual patient-level data that was not collected for the purpose of this study. Optimisation and validation of the model is necessary to allow clinical usability. We describe the type of data that needs to be collected to update our model, as well as the design of such validation study.
EP-1238: Thoracic re-irradiation following curative intent radiotherapy for non-small cell lung cancer
