On November 29, Boiselle et al. reported the results of a study (SSA04-02) at the annual meeting of the Radiological Society of North America: CT screening for lung cancer found that women have a higher risk of developing lung cancer than men for certain types of lung nodules. Lung nodules are small masses of lung tissue that are classified as solid or subsolid based on CT imaging: solid nodules are dense and obscure adjacent tissue, and subsolid nodules are subdivided into partially solid nodules (solid component with a hairy glassy or faint component) and pure hairy glassy material (no solid component). Nodule density is an indicator of risk for lung cancer, with partially solid nodules being the most associated with lung cancer. Phillip Boiselle, associate dean for academic and clinical affairs at Harvard Medical School from Beth Israel Deaconess Medical Center, reported, “We knew that there were differences in cancer risk among patients with different densities of lung nodules, but were not aware of gender differences in cancer risk among patients with lung nodule subtypes in the previously published literature.” The National Lung Cancer Screening Trial (NLST), a large randomized controlled trial demonstrating that CT screening reduces lung cancer deaths, enrolled more than 40% of patients who were women, making it difficult to achieve statistically significant differences in lung nodule and lung cancer identification between the sexes. dr. Boiselle and colleagues characterized nodules of 4-30 mm in the study’s database and calculated the relative risk of cancer for each nodule subtype. Of the 26,455 patients included in the study, 9,994 (37.8%) had a positive finding at ≥1 screening, and the relative risk of cancer was higher in women than in men for hairy, partially solid nodes. However, the relative risk of solid nodules was comparable between the sexes. Dr. Boiselle noted, “Women are more than 50% more likely than men to have a solid nodule, and when this nodule is present, women are actually at higher risk for lung cancer. “ Current lung cancer screening guidelines do not yet take into account gender differences for lung nodules of different densities. Although more research is needed to revise clinical practice guidelines, the results of this study suggest that women with glassy nodules need to be followed more closely than men. The investigators therefore concluded, “By looking at tumor growth rates on a series of lung cancer CT films, we can better understand and determine the frequency of CT follow-up for patients of both sexes.”