• Giulia Veronesi, Patrick Maisonneuve, Massimo Bellomi, Cristiano Rampinelli, Iara Durli, Raffaella Bertolotti, and Lorenzo Spaggiari.
• Division of Thoracic Surgery, European Institute of Oncology, Via Ripamonti 435, 20141 Milan, Italy. giulia.veronesi@ieo.it
• Ann. Intern. Med. 2012 Dec 4;157(11):776-84.

BackgroundLung cancer screening may detect cancer that will never become symptomatic (overdiagnosis), leading to overtreatment. Changes in size on sequential low-dose computed tomography (LDCT) screening, expressed as volume-doubling time (VDT), may help to distinguish aggressive cancer from cases that are unlikely to become symptomatic.ObjectiveTo assess VDT for screening-detected lung cancer as an indicator of overdiagnosis.DesignRetrospective estimation of the VDT of cancer detected in a prospective LDCT screening cohort.SettingNonrandomized, single-center screening study involving persons at high risk for lung cancer enrolled between 2004 and 2005 who received LDCT annually for 5 years.Patients175 study patients diagnosed with primary lung cancer.MeasurementsVDT was measured on LDCT and classified as fast-growing (<400 days), slow-growing (between 400 and 599 days), or indolent (≥600 days).ResultsFifty-five cases of cancer were diagnosed at baseline, and 120 were diagnosed subsequently. Of the latter group, 19 cases (15.8%) were new (not visible on previous scans) and fast-growing (median VDT, 52 days); 101 (84.2%) were progressive, including 70 (58.3%) fast-growing and 31 (25.8%) slow-growing (15.0%) or indolent (10.8%) cases. Lung cancer-specific mortality was significantly higher (9.2% per year) in patients with new compared with slow-growing or indolent (0.9% per year) cancer. Sixty percent of fast-growing progressive cancer and 45% of new cancer were stage I, for which survival was good.LimitationsThis is a retrospective study. Volume-doubling time can only indicate overdiagnosis and was estimated for new cancer from 1 measurement (a diameter of 2 mm assumed the previous year).ConclusionSlow-growing or indolent cancer comprised approximately 25% of incident cases, many of which may have been overdiagnosed. To limit overtreatment in these cases, minimally invasive limited resection and nonsurgical treatments should be investigated.Primary Funding SourceItalian Association for Cancer Research.

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