PolmoniAMO_INGL

15 PolmoniAMO very low (one fifth of the ionising radiation of a conventional CT scan), far lower than the natural background radiation and less than half of the naturally occurring radiation from the ground and the atmosphere to which the Italian population is exposed. International guidelines for lung cancer screening, currently adopted in the United States, recommend that LDCT is repeated each year, [35,36] for a minimum of three years, but at present the optimal frequency of screening remains a debated question in clinical research. Over the past decade, a wealth of scientific evidence has been accumulated in support of the efficacy of LDCT as a promising life-saving strategy capable of reducing lung cancer mor- tality in at-risk individuals [37]. In 2011, the National Lung Cancer Screening Trial (NLST) demonstrated that annual screening with LDCT resulted in a significant 20% reduction in 5-year lung cancer mortality rates compared to chest X-rays in a US population selected for their age and prolonged exposure to tobacco. These findings have enabled LDCT to be included as a screening tool recommended by the US Preventive Services Task Force for adults aged 55-80 years with a significant smoking history [34,37]. The NELSON study, started in 2003, recently helped confirm the validity and effectiveness of LDCT in screening for lung cancer [38]. In this study, 15,792 at-risk individuals, selected by age and smoking habit, were randomised in a 1:1 ratio to either the study group or the con- trol group. Participants in the study group were offered repeated examinations by LDCT when beginning the study, and after 1, 3 and 5 years after randomisation. Conversely, no radiological examinations was offered to participants in the control group. A reduction in 10-year mortality [2.5 deaths per 1,000 patients per year versus 3.3 deaths per 1,000 pa- tients per year in the control group (no screening)] was observed in subjects undergoing LDCT screening. Furthermore, those who underwent LDCT showed a reduction in lung cancer-associated mortality of 24% (cumulative incidence ratio per lung cancer death: 0.76; P=0.01). It is worth noting that 77.6% of the lung cancers diagnosed in the study group were stage IA to II cancers, indicating how early diagnosis can significantly re- duce mortality [24]. In the same years, the Multicenter Italian Lung Detection Trial (MILD) was conducted in our country on more than 4,000 heavy smokers in whom thoracic LDCT was scheduled to take place, either annually or biannually, for a follow-up period of 10 years [2,39]. The MILD study differs from other randomised trials in that it allowed for the convergence of three objectives: primary prevention, early diagnosis, and quantification of individual risk using the most advanced diagnostic and molecular biology techniques. The MILD Study began as a free screening programme aimed at heavy smokers who, once enrolled, were encouraged to stop smoking and underwent spirometric and blood tests. A layered ran- domisation system subsequently identified subjects to be monitored with spiral CT scans on an annual or biannual basis. The aim of the study was to detect early-stage lung can- cer and intervene early, thereby minimising the functional damage of surgery as much as possible. Furthermore, unlike the NLST and NELSON studies, the MILD study, in addition to LDTC, made use of PET scans and proactive monitoring in order to minimise unnec-