Response to “Is post-operative radiotherapy of any benefit after R0 resection for N2 disease?”

We thank Drs Cerfolio and Estes (1) for their comments in regard to our recently published analysis from the National Cancer Data Base (NCDB) exploring the utility of post-operative radiotherapy (PORT) in completely resected N2 non-small cell lung cancer (NSCLC) treated with adjuvant chemotherapy (2). As they note, while the strength of such a multi-institutional database lies in its numbers (in this case, more than 4,000 patients), there is an expected loss of data fidelity and granularity. For example, in our analysis we had a limited ability to explore questions of lymph node station involvement, number of nodes, or completeness of lymph node sampling due to incomplete or completely missing data. As such, we could not control for these variables in our multivariate modeling. However, with respect to questions of lymph node involvement or sampling, it would be expected that those patients with less favorable features (incomplete dissection, more lymph node involvement, etc.,) would be more likely to receive PORT. It if were possible to account for this likely stacking of less favorable patients in the PORT group, it seems possible that we may have seen an even larger benefit to PORT. Nonetheless, such an imbalance could not reverse the survival curves, and therefore we believe our overall conclusions remain sound. Additionally, we appreciate Dr. Cerfolio and Estes’ kind comments regarding the importance of our analysis in the absence of randomized data, and echo our support for randomized trials such as Lung ART.