Exposure to low dose computed tomography for lung cancer screening and risk of cancer: secondary analysis of trial data and risk-benefit analysis.
ObjectiveTo estimate the cumulative radiation exposure and lifetime attributable risk of cancer incidence associated with lung cancer screening using annual low dose computed tomography (CT).DesignSecondary analysis of data from a lung cancer screening trial and risk-benefit analysis.Setting10 year, non-randomised, single centre, low dose CT, lung cancer screening trial (COSMOS study) which took place in Milan, Italy in 2004-15 (enrolment in 2004-05). Secondary analysis took place in 2015-16.ParticipantsHigh risk asymptomatic smokers aged 50 and older, who were current or former smokers (≥20 pack years), and had no history of cancer in the previous five years.Main outcome measuresCumulative radiation exposure from low dose CT and positron emission tomography (PET) CT scans, calculated by dosimetry software; and lifetime attributable risk of cancer incidence, calculated from theBiological Effects of Ionizing Radiation VII(BEIR VII) report.ResultsOver 10 years, 5203 participants (3439 men, 1764 women) underwent 42 228 low dose CT and 635 PET CT scans. The median cumulative effective dose at the 10th year of screening was 9.3 mSv for men and 13.0 mSv for women. According to participants' age and sex, the lifetime attributable risk of lung cancer and major cancers after 10 years of CT screening ranged from 5.5 to 1.4 per 10 000 people screened, and from 8.1 to 2.6 per 10 000 people screened, respectively. In women aged 50-54, the lifetime attributable risk of lung cancer and major cancers was about fourfold and threefold higher than for men aged 65 and older, respectively. The numbers of lung cancer and major cancer cases induced by 10 years of screening in our cohort were 1.5 and 2.4, respectively, which corresponded to an additional risk of induced major cancers of 0.05% (2.4/5203). 259 lung cancers were diagnosed in 10 years of screening; one radiation induced major cancer would be expected for every 108 (259/2.4) lung cancers detected through screening.ConclusionRadiation exposure and cancer risk from low dose CT screening for lung cancer, even if non-negligible, can be considered acceptable in light of the substantial mortality reduction associated with screening.
Department of Medical Imaging and Radiation Sciences, European Institute of Oncology, Milan, Italy cristiano.rampinelli@ieo.it.
Cristiano
C
Rampinelli
Medical Physics School, University of Milan, Milan, Italy.
Paolo
P
De Marco
Division of Medical Physics, European Institute of Oncology, Milan, Italy.
Daniela
D
Origgi
Division of Epidemiology and Biostatistics, European Institute of Oncology, Milan, Italy.
Patrick
P
Maisonneuve
Division of Thoracic Surgery, European Institute of Oncology, Milan, Italy.
Monica
M
Casiraghi
Division of Thoracic Surgery, European Institute of Oncology, Milan, Italy.|Division of Thoracic Surgery, Humanitas Research Hospital, Rozzano, Italy.
Giulia
G
Veronesi
Division of Thoracic Surgery, European Institute of Oncology, Milan, Italy.|Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy.
Lorenzo
L
Spaggiari
Department of Medical Imaging and Radiation Sciences, European Institute of Oncology, Milan, Italy.|Department of Oncology and Hematology-Oncology, University of Milan, Milan, Italy.
Massimo
M
Bellomi
D000328:Adult; D055088:Early Detection of Cancer; D005260:Female; D006801:Humans; D015994:Incidence; D007558:Italy / Q000453:epidemiology; D008175:Lung Neoplasms / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology; D008297:Male; D008403:Mass Screening / Q000009:adverse effects / Q000379:methods; D008875:Middle Aged; D009381:Neoplasms, Radiation-Induced / Q000175:diagnosis / Q000453:epidemiology / Q000209:etiology / Q000517:prevention & control; D049268:Positron-Emission Tomography / Q000009:adverse effects / Q000379:methods; D011829:Radiation Dosage; D018570:Risk Assessment; D012307:Risk Factors; D012907:Smoking / Q000009:adverse effects*; D014057:Tomography, X-Ray Computed / Q000009:adverse effects / Q000379:methods