Clinical implications and added costs of incidental findings in an early detection study of lung cancer by using low-dose spiral computed tomography

Introduction: To prospectively evaluate the frequency and spectrum of incidental findings (IF) in a 5-year lung cancer screening program with low-dose spiral computed tomography (CT) and to estimate the additional costs of their imaging workup incurred from subsequent radiologic follow-up evaluation.

Materials and methods: A total of 519 asymptomatic volunteers were enrolled. All IFs were reported and were considered clinically relevant if they required further evaluations or with clinical implications if they required more than one additional diagnostic test for characterization or medical and/or surgical intervention.

Results: IFs were commonly found (59.2%, 307/519 participants at baseline and 5.3% per year at 5-year follow-up [123 participants of 2341 LDsCT exams performed during follow-up], with an overall rate of 26.3%). IFs were categorized as previously unknown clinically relevant in 52 (10.0%) individuals at baseline. Of these, 36 (6.9%) individuals had IFs with clinical implications (10 clinically relevant, of which 6 had clinical implications, detected during the subsequent 5-year follow-up). The most common recommendations were for additional imaging of the thyroid and kidneys. Additional imaging was mainly performed by ultrasound (43/68 [63.2%]). Subsequent surgical intervention resulted from these findings in 7 (1.5%) subjects. Six malignancies were diagnosed (rate, 0.2% per year). Costs of subsequent radiologic follow-up studies were calculated as €4644.56 [U.S. $6575.04] at baseline and €1052.30 [U.S. $1489.69] at 5-year follow-up (average added costs per participant €8.95 [U.S. $12.67] and €2.25 [U.S. $3.19], respectively).

Conclusions: Low-dose spiral CT commonly detects IFs. Some of these require further investigations to assess their clinical relevance. Although such IFs add little clinical benefit to the screening intervention, moderate incremental costs are incurred based on additional radiologic procedures generated during short-term follow-up, given the potential for positive effects on patient care.