In "Reduced Lung-Cancer Mortality with Low-Dose Computed Tomographic Screening," the authors state that "a total of 96.4% of the positive screening results in the low-dose CT group and 94.5% in the radiography group were false positive results [emphasis added]." Had to read that line several times just to make sure.
The authors also state that there was a 20% relative risk reduction in mortality in the CT vs the radiography group. Besides the fact that translates to an absolute risk reduction of a measly 0.062% (1 in 1,613 screened people), there doesn't seem to be any mention of how a non-screened group would fare or had fared.
To their credit the authors do note that:
In addition to the high rate of false positive results, two other potentially harmful effects of low-dose CT screening must be mentioned. Overdiagnosis, a major source of controversy surrounding low-dose CT lung-cancer screening, results from the detection of cancers that never would have become symptomatic.... The other harmful effect, the association of low-dose CT with the development of radiation-induced cancers, could not be measured directly, is a long-term phenomenon, and must be assessed in future analyses.