Indolent, Potentially Inconsequential Lung Cancers in the Pittsburgh Lung Screening Study

Rationale: The finding of indolent, potentially inconsequential cancers (overdiagnosis) is inherent to cancer screening in general, and there is a growing body of literature about this concept in lung cancer screening. Objectives: We report on indolent, potentially inconsequential lung cancers in the Pittsburgh Lung Screening Study (PLuSS) population screened for lung cancer with annual low-dose computed tomography. Methods: We identified 93 subjects with screen-detected prevalence cancers in PLuSS. We defined indolent, potentially inconsequential cancers as stage I prevalence lung cancer cases that had volumetric doubling time >400 days (when available) and maximal standardized uptake value max on positron emission tomography (PET) scan <= 1 (when available). Measurements and Main Results: Approximately 18.5%(n = 17) of all 93 screen-detected prevalence lung cancers in PLuSS were indolent, potentially inconsequential cancers. All such cancers except for one were adenocarcinomas by histology. Median tumor size of such cancers at the time of final diagnosis was 10 mm (range, 7-22 mm). Median doubling time was significantly longer in this group when compared with the rest of the prevalence stage 1 cancers (752 vs. 284.5 d). Conclusions: Although the precise definitions may vary, the existence of indolent, potentially inconsequential cancers in low-dose computed tomography lung cancer screening is real. Clinicians involved in managing patients with low-dose computed tomography-detected slow-growing nodules, especially with a standardized uptake value <= 1 on PET scan, should consider the possibility of indolent, potentially inconsequential cancer in the longitudinal management of these nodules.