P2.11-02 Direct Comparison of New Solid Nodules Detected in Women and Men During Incidence Screening Rounds of the NELSON Trial

Abstract

Low-dose computed tomography (LDCT) lung cancer screening is recommended by US guidelines. Women are commonly underrepresented in lung cancer screening trials and evidence is derived from a predominantly male population. New solid nodules that develop after baseline screening have a high lung cancer probability. There is very limited evidence concerning the potential differences of new solid nodules detected in women and men. In the randomized Dutch-Belgian Lung Cancer Screening (NELSON) Trial, 7,557 participants (16% female) underwent baseline screening. Three incidence rounds took place after intervals of 1year, 2years and 2.5years respectively. We included participants with solid non-calcified nodules registered after baseline as new and not visible in retrospect on a previous screen. Continuous variables were compared using the Mann–Whitney U test or student's t test and are presented as medians with interquartile range (IQR) or means with standard deviation (±) respectively. Nominal variables were compared using the chi-squared test. In total, 699 participants (149 [21%] women, 550 [79%] men) with 1,130 new solid nodules (241 [21%] in women, 889 [79%] in men) were included. Eventually, 5.4% of women with a new solid nodule and 10.4% of men with a new solid nodule were diagnosed with lung cancer (P=0.063), corresponding to 3.3% of new solid nodules being malignant in women and 6.5% being malignant in men (P=0.060). The female participants were significantly younger than the male participants (58±5 years vs. 60±5 years, P=0.008), while there was no significant difference in smoking pack-years (39 years [IQR 30-49] vs. 39 years [IQR 30-52], P=0.696). Comparing new nodule size at initial detection in women and men, there was a significant difference for benign new nodules (51mm3, IQR: 29-128mm3 vs. 66mm3, IQR: 35-177mm3, P=0.019), but not for lung cancers (449mm3, IQR: 52-1050mm3 vs. 447mm3, IQR: 196-1135mm3, P=0.553). The currently advocated cutoff of ≥30mm3 (about 3.9mm) reached >95% sensitivity in both genders. At first follow-up after detection, new solid nodules in women had resolved significantly more frequent than in men (69% vs. 58%, P=0.003). Adenocarcinomas were significantly more common in women than in men (88% of lung cancers vs. 31% of lung cancers, P=0.002), whereas the stage I detection rate was comparable (67% of lung cancers vs. 63% of lung cancers, P=0.789). While there are significant differences between new solid nodules detected after baseline in women and men, there is no indication for a sex specific nodule management approach in LDCT lung cancer screening.