Annual screening with X-rays does not reduce lung cancer deaths

27 October 2011

A trial involving 150,000 patients that gave half annual chest X-rays for up to four years showed that screening did not significantly reduce death from lung cancer compared to the unscreened group.

 The study is being published early online and in the November 2 issue of JAMA.

Martin M. Oken, M.D., of the University of Minnesota, and colleagues examined the effect on mortality of screening for lung cancer using radiographs in the Prostate, Lung, Colorectal, and Ovarian (PLCO) Cancer Screening Trial. This randomized controlled trial involved 154,901 participants, ages 55 through 74 years, of whom 77,445 were assigned to annual screenings and 77,456 to usual care, at 1 of 10 screening centers across the United States, between November 1993 and July 2001.

Participants in the intervention group were offered an annual chest radiograph for four years. Diagnostic follow-up of positive screening results was determined by participants and their health care practitioners. Participants in the usual care group were not offered chest radiograph screening and received their usual medical care. All diagnosed cancers, deaths, and causes of death were ascertained through the earlier of 13 years of follow-up or until December 31, 2009.

During the entire 13-year study period, there were 1,696 lung cancers detected in the intervention group and 1,620 lung cancers in the usual care group. Of participants diagnosed with lung cancer during the follow-up, stage and histology was similar by group, with about 41% being adenocarcinoma, 20% squamous cell carcinoma, 14% small cell carcinoma, 5% large cell carcinoma, and 20% other non-small cell lung cancer.

Regarding the effect on mortality, the researchers found that annual chest radiographic screening for up to four years did not significantly decrease lung cancer mortality compared with usual care: for the total 13-year follow-up period, 1,213 lung cancer deaths were observed in the intervention group vs. 1,230 in the usual care group.

"The randomized groups in PLCO were comparable at baseline, there was relatively high screening adherence in the intervention group and low contamination in the usual care group, and the treatment distributions across the groups were similar. Therefore, these findings provide good evidence that there is not a substantial lung cancer mortality benefit from lung cancer screening with 4 annual chest radiographs," the authors write.