Meta-analysis comparing higher and lower dose radiotherapy for palliation in locally advanced lung cancer.

Dear Editor,

In the context of an update of the Dutch guideline on non-small-cell lung cancer, we performed a systematic review on the clinical effectiveness of low-dose (i.e. <30 Gy) versus high-dose palliative radiotherapy (i.e. ≥30 Gy). We identified the recent meta-analysis of Ma et al.1 that included five randomized trials published until June 2013. Our systematic review confirmed the completeness of the search of Ma et al. However, when we examined the forest plot of the effect on 1-year overall survival, the Dutch trial of Kramer et al.2 was found to be discordant with the four other included studies. Verification of the full-text publication confirmed that Kramer's results were wrongly extracted by Ma et al. (high-dose, 11% instead of 20%; low-dose, 20% instead of 11%), possibly resulting in an underestimation of the pooled effect and wrong conclusions. We would like to ask the authors to redo the meta-analysis with the correct data, and to reconsider the conclusions based on the new results.