Five hundred thirty-eight of 718 screening candidates (74%) not meeting group 1 criteria did fulfill the group 2 age and smoking criteria and were found to have at least one additional qualifying NCCN risk factor (Figs. 2 and 3). Three hundred twelve of 2,391 (12%) did not meet either high-risk criteria and were assigned to group 3 and not enrolled in the screening

program. Four hundred sixty-four of 538 group 2 subjects (86%) and 1,296 of 1,541 group 1 subjects (84%) underwent prevalence CT lung screening examinations during the study interval, for a total of 1,760 examinations (26% in group 2) (Table 1). Demographics and smoking histories of group 2 and group 1 patients scanned are presented in Table 1. Four hundred eighty-one of 1,760 prevalence examinations (27.3%) had positive findings: this website 25.0% in group 2 and 28.2% in group 1. One hundred eight of 1,760 prevalence examinations (6.1%) had at least one clinically significant incidental finding: SB203580 purchase 6.0% in group 2 and 6.2% in group 1. One hundred fourteen of 1,760 prevalence examinations (6.5%) had findings suspicious for pulmonary infection or inflammation: 6.0% in group 2 and 6.6% in group 1 (Table 2). Four hundred thirty-two of 1,760 screened individuals (28%) were patients from outside our institution,

for whom clinical follow-up after the prevalence CT lung screening examinations was not available during this retrospective review. For the remaining 1,328 patients, overall average clinical follow-up after the prevalence examination was 12.5 months: 12.1 ± isothipendyl 6.5 months (range, 2.1–25.5 months) in group 2 and 12.7 ± 6.5 months (range, 2.1–25.7 months) in group 1

(Table 1). Twenty-three of 1,328 screened patients (1.6%) with clinical follow-up were diagnosed with at least one lung cancer: 6 of 331 (1.8%) in group 2 and 17 of 997 (1.7%) in group 1. The overall annualized rate of malignancy detection was 1.6%: 1.8% in group 2 and 1.6% in group 1. Overall average time from prevalence examination to cancer diagnosis was 4.1 months: 5.6 months in group 2 and 3.7 months in group 1. Eleven of 23 patients (48%) had adenocarcinoma, 5 (22%) had squamous cell carcinoma, 2 (9%) had small cell carcinoma, 1 (4%) had a carcinoid, and 1 (4%) had 3 synchronous small primary lung cancers, squamous cell carcinoma, adenocarcinoma, and adenosquamous carcinoma. Three patients (13%) deemed unable to tolerate biopsy were diagnosed with stage I lung cancer on the basis of PET positivity, suspicious growth rate, and multidisciplinary consensus and were subsequently treated with stereotactic body radiotherapy. Fourteen of 23 cancer patients (61%) were in stage I, 4 (17%) were in stage II, 2 (9%) were in stage III, and 3 (13%) were in stage IV at time of diagnosis. Twenty-one of 23 patients (91%) with diagnosed lung cancer were alive at the time of retrospective review. Of those alive, 14 (61%) had no evidence of disease. Average overall follow-up was 7.