Extrapulmonary malignancies detected at lung cancer screening

To retrospectively assess the detection rate, histologic characteristics, and clinical stage of screening-detected extrapulmonary malignancies in a population at high risk for lung cancer.

In this institutional review board-approved study, 5201 asymptomatic heavy smokers aged 50 years or older underwent annual low-dose computed tomography (CT) for 5 consecutive years. The 5-year cumulative effective dose was 5 mSv. Subjects with at least one "potentially significant extrapulmonary incidental finding" (PS-IF) were extracted from the study database. An extrapulmonary finding was classified as potentially significant if it required further diagnostic and/or clinical evaluation. In retrospect all clinically relevant information, including findings from diagnostic work-up and final diagnosis of the PS-IF, was collected. On the basis of the information collected, only histologically proved screening-detected extrapulmonary malignancies were eventually included in this study. The percentages of volunteers with extrapulmonary malignancies were calculated, along with 95% confidence intervals (CIs), on the basis of a binomial distribution.

After 5 years of CT screening, 27 unsuspected extrapulmonary malignancies were diagnosed, representing 0.5% (27 of 5201 subjects; 95% CI: 0.34%, 0.75%) of volunteers enrolled and 6.2% (27 of 436 findings; 95% CI: 4.12%, 8.88%) of PS-IFs. Eight malignancies were diagnosed at the 1st year of screening, nine at the 2nd year, four at the 3rd year, two at the 4th year, and four at the 5th year. Twelve of the 27 extrapulmonary tumors (44%) were renal carcinomas (n = 7) or lymphomas (n = 5). Twenty-four of the 27 subjects with a malignancy were alive at the most recent follow-up.

A considerable number of unsuspected extrapulmonary malignancies can be detected in lung cancer screening trials. A careful evaluation of extrapulmonary structures, with particular attention to the kidneys and lymph nodes, is recommended.