External Validation of a Prognostic Score for Patients Receiving Palliative Thoracic Radiotherapy for Lung Cancer

Palliative thoracic radiotherapy is a common treatment for patients with incurable lung cancer. A recent study suggested that a prognostic score based on performance status and N and M stage predicts survival and might support decision-making (eg, when deciding about fractionation). Our aim was to perform a validation study in an independent, larger dataset.

This was a retrospective single-institution study of 232 patients with small- or non-small-cell lung cancer, with methodology comparable with that of the original study. Three subgroups were created, based on the point sum resulting from assessment of performance status and N and M stage (10-11, 12-14, 15-17 points).

Performance status and N and M stage were significantly associated with overall survival after palliative radiotherapy in uni- and multivariate analyses. An unfavorable prognosis (10-11 points) was predicted in 56 patients (24%). Their median survival was 1.2 months. The intermediate group consisted of 137 patients (59%) with a median survival of 5.3 months. A favorable prognosis (15-17 points) was predicted in 39 patients (17%), whose median survival was 8.2 months. The difference between the intermediate and favorable subgroups did not reach statistical significance (P = .1, as compared with P = .0001 for the remaining 2 comparisons).

In the original study, the median survival of patients in the 3 different prognostic strata was 2, 6, and 38 months. Except for the favorable subgroup, the validation study confirmed these results. Given the large, clinically highly relevant discrepancy (8 vs. 38 months), additional studies are needed in order to inform therapeutic decisions in patients with favorable point sum of 15 to 17.