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. Author manuscript; available in PMC: 2015 Jan 27.
Published in final edited form as: Clin Chest Med. 2008 Mar;29(1):1–v. doi: 10.1016/j.ccm.2007.12.001

Figure 1.

Figure 1

The effects of the biases of lead time, length, and overdiagnosis on increased survival, independent of improved longevity or mortality reduction. (A) Lead time from the early detection of a lung cancer by screening will prolong survival independent of any delay in death. (B) Screen-detected lung cancers tend to be more indolent than symptom-detected or intervals cancers diagnosed between screenings. The survival benefit associated with these favorable cancers is ascribed to the screening test, even if screening does nothing to reduce the number of advanced stage cancers or lung cancer deaths. (C) The pseudodisease detected because of overdiagnosis bias markedly increases survival, regardless of whether screening or associated treatments are effective.