Table 3 Estimated duration of lead time of lung cancer detected by sputum cytology (SC) in patients with normal chest radiography (CR). The prevalenceand incidence of lung cancers detected by SC alone in persons with normal CR were derived from the data reported by the authors
Trial and authors | Study population (n) | Prevalence of squamous cell cancers per 1000 at T0 | Average duration of screening (years) | Average annual incidence of confirmed squamous cell lung cancers per 1000 during screening | Lead time (years) | ||||||
|---|---|---|---|---|---|---|---|---|---|---|---|
Intervention | Control | Intervention detected by SC alone (a) | Control detected by SC alone (b) | Intervention, detected by SC alone (c) | Intervention, interval cancers (d) | Control, CR- detected cancers (e) | Control, interval cancers (f) | a/(c + d) | a/(e + f) | ||
4618 | 4593 | 1.8 | 6 | 0.7 | 0.6* | Not applicable | 1.0* | 1.3 | 1.8 | ||
John Hopkins study: Frost et al. 1984 [10]; Doria-Rose et al. 2009 [11]b | 5226 | 5161 | 2.1 | Not applicable | 7.2 | 0.9 | 0.5 | 0.8 | 0.9 | 1.5 | 1.2 |
Memorial Sloan Kettering: Melamed et al. 1984 [12]; Doria-Rose et al. 2009 [11]b | 4968 | 5072 | 1.8 | Not applicable | 7.2 | 0.8 | 0.4 | 0.7 | 0.8 | 1.5 | 1.2 |