Radiologic Features of Nodules Attached to the Mediastinal or Diaphragmatic Pleura at Low-Dose CT for Lung Cancer Screening.

Background Pulmonary noncalcified nodules (NCNs) attached to the fissural or costal pleura with smooth margins and triangular or lentiform, oval, or semicircular (LOS) shapes at low-dose CT are recommended for annual follow-up instead of immediate workup. Purpose To determine whether management of mediastinal or diaphragmatic pleura-attached NCNs (M/DP-NCNs) with the same features as fissural or costal pleura-attached NCNs at low-dose CT can follow the same recommendations. Materials and Methods This retrospective study reviewed chest CT examinations in participants from two databases. Group A included 1451 participants who had lung cancer that was first present as a solid nodule with an average diameter of 3.0-30.0 mm. Group B included 345 consecutive participants from a lung cancer screening program who had at least one solid nodule with a diameter of 3.0-30.0 mm at baseline CT and underwent at least three follow-up CT examinations. Radiologists reviewed CT images to identify solid M/DP-NCNs, defined as nodules 0 mm in distance from the mediastinal or diaphragmatic pleura, and recorded average diameter, margin, and shape. General descriptive statistics were used. Results Among the 1451 participants with lung cancer in group A, 163 participants (median age, 68 years [IQR, 61.5-75.0 years]; 92 male participants) had 164 malignant M/DP-NCNs 3.0-30.0 mm in average diameter. None of the 164 malignant M/DP-NCNs had smooth margins and triangular or LOS shapes (upper limit of 95% CI of proportion, 0.02). Among the 345 consecutive screening participants in group B, 146 participants (median age, 65 years [IQR, 59-71 years]; 81 female participants) had 240 M/DP-NCNs with average diameter 3.0-30.0 mm. None of the M/DP-NCNs with smooth margins and triangular or LOS shapes were malignant after a median follow-up of 57.8 months (IQR, 46.3-68.1 months). Conclusion For solid M/DP-NCNs with smooth margins and triangular or LOS shapes at low-dose CT, the risk of lung cancer is extremely low, which supports the recommendation of Lung Imaging Reporting and Data System version 2022 for annual follow-up instead of immediate workup. © RSNA, 2024 See also the editorial by Goodman and Baruah in this issue.

Race, age at diagnosis and histological characteristics of lung cancer in never-smokers (LCINS) and ever-smokers in low-dose computed tomography (LDCT) screening: a systematic review and meta-analysis.

Background: We previously demonstrated in a meta-analysis there was no difference in risk ratio (RR) of lung cancer detected by low-dose computed tomography (LDCT) screening among female never-smokers (NS) and male ever-smokers (ES) in Asia. LDCT screening significantly decreased lung cancer death among Asian NS compared to Asian ES (RR =0.27, P<0.001). Methods: We investigated if race, age at diagnosis, and histology further differentiate lung cancer diagnosed by LDCT among in NS and ES using the 14 studies from our previous meta-analysis. Results: Twelve publications reported relevant data utilized in this study. From five Asian and one international studies, Asian ES had similar risk of lung cancer diagnosed at baseline screening as Asian NS [RR =0.96; 95% confidence interval (CI): 0.74-1.24] but among non-Asian ES had a 4.56 times significantly higher risk than non-Asian NS (RR =4.56; 95% CI: 2.85-7.28). The baseline incidence of lung cancer in never-smoker (LCINS) was approximately 2.3 times higher among Asian NS than non-Asian NS (0.62% vs. 0.27%, P=0.001). Asian ES had about half the baseline incidence of lung cancer diagnosed as non-Asian ES (0.65% vs. 1.26%). LCINS was diagnosed at 1.98 years younger than ES (95% CI: -3.38 to -0.58) (four studies) and exhibited a higher proportion of adenocarcinoma (ADC) (96.58% vs. 70.37%). Conclusions: Among normal-risk individuals, LCINS had a significantly higher likelihood of being diagnosed among Asians than non-Asians, predominantly manifesting as ADC and diagnosed approximately 2 years younger than ES suggesting that the age limit to initiate lung cancer screening in NS may be set lower compared to LDCT lung cancer screening among ES.