Women with a specific form of lung nodule evident in lung cancer screening CT tests are at increased risk of lung cancer compared to men with identical lung nodules. These were the results of a study recently presented during the Radiological Society of North America (RSNA) annual conference.
A pulmonary nodule is a small round or oval-shaped growth in the lung. It is also sometimes called a spot on the lung or a coin lesion. Pulmonary nodules are generally smaller than 3 centimeters in diameter. If the growth is larger than that, it is known as a pulmonary mass and is more likely to represent a cancer. There are two main types of pulmonary nodules: malignant (cancerous) and benign (noncancerous), with over 90% of pulmonary nodules smaller than 2 centimeters in diameter proved to be benign.
Lung nodules are categorized as solid or subsolid based on their appearance on CT scan. Solid nodules are dense, and they obscure adjacent tissue, while subsolid nodules are split into two different categories: part solid and pure ground glass, devoid of solid elements. Importantly, nodule consistency is an indicator of risk of lung cancer. “We know there are differences in cancer risk among different lung nodule consistencies, but we were unaware of any published reports that looked at the differences in lung cancer risk for nodule subtypes between women and men,” said study lead author Phillip Boiselle, M.D., from Beth Israel Deaconess Medical Center and Harvard Medical School in Boston, in a recent news release.
Dr. Boiselle and colleagues assessed CT scans from the National Lung Screening Trial (NLST), a randomized control trial that confirmed the value of CT scans to reduce mortality rates related with lung cancer. For the NLST study over 40% of the participants were women, allowing the team to perform comparative statistical analysis in lung nodules and cancer between sexes. Using the NLST database, the team characterized all CT-detected nodules that measured between 4 and 30 millimetres by consistency (n= 26,455 participants). The relative risk of lung cancer was examined for each nodule consistency subtype.
The results revealed that 37.8% of the participants (n=9,994), screened positive at one or more points during the study period. Furthermore, when compared to men, women with ground-glass nodules were at higher risk of lung cancer. A similar trend was observed for gender comparisons of part-solid nodules. However, the results demonstrated that the relative risk for solid nodules was similar among men and women.
The researchers were also able to determine that part-solid lung nodules were the most predictive of lung cancer among men and women, whereas solid nodules and ground glass nodules were found be less predictive in women and men, respectively. “The main difference we found was that women were 50 percent more likely than men to have ground-glass nodules and, when these nodules were present, women had a substantially higher risk of developing lung cancer,” said Dr. Boiselle.
For the management of lung nodules of different consistencies, gender differences are not considered in current lung cancer screening guidelines. While more studies are necessary before modifications are made to clinical practice, the findings from this study indicate that women with ground glass nodules may require closer clinical follow-up than men. “By looking at the rate at which lung cancers grow on serial CT scans, we can develop a better understanding of how often to obtain follow-up CT scans in men and women,” Dr Boiselle added.
