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Lung cancer screening using low-dose computed tomography: The Toronto experience Heidi Roberts 1 Demetris Patsios 1 Narinder Paul 1 TaeBong Chung 1 Scott Boerner 2 Thomas Waddell 3 Shafique Keshavjee 3 Gail Darling 3 Ming Tsao 2 Frances Shepherd 4 Depts. of 1 Medical Imaging, 2 Pathology, 3 Thoracic Surgery, 4 Medical Oncology - Princess Margaret Hospital / University Health Network, Toronto, ON, Canada Purpose We report our initial results from the ongoing lung cancer screening study using low-dose computed tomography (LDCT) in Toronto, Canada. Methods As part of the International Early Lung Cancer Action Project (I-ELCAP), we enrolled 400 high-risk smokers between June 2003 and November 2004. A helical CT was performed with 1.25mm overlapping slices, in low-dose technique (60mA, 120kV). Nodules found on baseline screening were followed up according to the I-ELCAP protocol: (1) no non-calcified nodules (NCN) or NCN ≤4mm or non-solid nodules ≤8 mm: annual repeat; (2) indeterminate NCN ≥5 mm or non-solid nodules ≥8 mm: 3 months follow up, (3) indeterminate non-solid nodules ≥15 mm: antibiotics and 1 month follow-up (see flowchart). Results The first 400 patients were 63 6 years old and had a smoking history of 43 25 pack-years. 186 (46.5%) were men, 214 (53.5%) were women. On baseline screening CT, 63 (16%) had no nodules, 273 had at least one NCN ≤4 mm or non-solid nodule ≤8 mm. 291 (73%) patients are invited for annual follow up CTs, one for a contrast-enhanced abdominal CT. 108 (27%) had indeterminate nodules that needed to be followed up: 6 after antibiotics and 1 month, 101 after 3 months, 1 had an immediate biopsy. 4 of the nodules followed up after 1 month had not resolved, and 4 of the solid nodules had grown after 3 months, resulting in 9 indications for CT-guided biopsies (2.3% of 400). All 9 biopsies revealed cytologic evidence of malignancy. Subsequently, surgical resection was performed in 8 patients, one patient underwent chemoradiation. Surgical resection confirmed cancer in 7 cases, but found chronic lung injury in one. Conclusion Our results confirm that LDCT identifies small, non-symptomatic lung cancers in a high risk population. Baseline low-dose CT normal or calcified nodules (any size) or nodules smaller than 5 mm solid nodules 5 mm or larger or non-solid nodules 8 mm or larger non-solid nodules 1.5 cm or larger annual follow-up screening CT antibiotics and follow-up CT in 1 month follow-up CT in 3 months n = 291 73% n = 6 n = 2 spiculated, 2.5 cm mass n = 1 immediate biopsy n = 108 / 27% n = 4 non-resolved grown stable n = 4 biopsy n = 9 cytologic evidence of malignancy surgery n = 8 n = 1 chemoradiation chronic lung injury n = 1 n = 7 cancer Summary In the first 400, we found - 8 cancers (2%) - all 8 in women - all 8 Stage I - 7 adenocarcinoma /BAC, 1 squamous cell cancer n = 101 n = 97 resolved Baseline LDCT (a) shows a solid mass in the right lower lobe (arrow), which has completely resolved after 1 month (b). b Baseline LDCT (a) shows a part-solid nodule in the right lower lobe (arrow), which is unchanged after 1 month (b). a Baseline LDCT (a) shows a solid pleura-based nodule in the left lower lobe (arrow), adjacent to an old rib fracture (b). Three months later it had grown (c). Biopsy / cytology were highly suspicious for well differentiated adenocarcinoma, wedge resection and histology showed organizing / proliferative phase acute lung injury, no evidence of malignancy. b a c b a Baseline LDCT shows a 2.5 cm spiculated mass (arrow), which was biopsied (adenocarcinoma); patient received chemoradiation. Baseline LDCT shows a 8 mm nodule (arrow), which is stable after 6 months. b a c Baseline LDCT (a) shows a lobulated left upper lobe nodule (arrow). Three months later it had grown (b). Biopsy / cytology (c) showed abnormal mucinous epithelium, surgical resection and histology confirmed mucinous bronchioloalveolar carcinoma.