Less is more in radiation for lung cancer

The optimal radiation dose for treating lung cancer was established more than 30 years ago, but improved technology led some radiation oncologists to experiment with higher doses. The results of a phase 3 trial comparing the standard dose (SD) radiotherapy with high-dose (HD) radiotherapy indicate that less is more, a least in terms of controlling the disease and prolonging survival."Conventional thinking has been that if one could give a higher dose of radiation, one could effectively kill the tumor better and thus prolong survival," said Jeffrey D. Bradley, a professor of radiation oncology at the Washington University School of Medicine in St. Louis and the study's lead author. In the past decade, he explained, several independent cooperative groups conducted a series of phase 1 and phase 2 trials that increased the radiation (measured in units called Gray, or Gy) from the standard 60 Gy to the higher 74 Gy, showing the safety and effectiveness of the higher dose."This phase 3 trial was designed to test this high-dose question," he said during a press conference leading up to the annual meeting of the American Society of Clinical Oncology (ASCO). The median survival for participants in the SD arm was more than nine months longer compared with participants in the HD arm. Moreover, recurrence rates were almost 10 percent higher among participants in the HD arm. "I'm sure that many doctors were expecting that using the higher doses would have a better outcome, so this is a very surprising result," said Sandra M. Swain, ASCO president. "And especially when using these special radiation techniques that were designed to be more precise so you would again expect that maybe the outcome would be better. This really should put an end to higher dose treatment, given the better outcomes in the standard dose arm."In the study, 464 participants with stage 3 non-small cell lung cancer were randomized to receive either SD or HD concurrently with chemotherapy (paclitaxel and carboplatin). Additionally, participants in both arms were randomized to receive Erbitux (cetuximab), but data on that aspect of the study was not yet available."A lot of phase 3 trials turn out negative when phase 2 trials turn out looking good," Bradley said in discussing the results. "So it was good to do a phase 3 trial and get this answered."