PET/CT roots out early lung cancer subtypes, may help personalize treatment

Combining fluorodeoxyglucose (FDG) PET with high-resolution CT can help predict subtypes of early lung adenocarcinoma—a form of cancer that is on the rise.

Lung adenocarcinoma can be divided into five different subtypes depending on growth pattern, with each carrying a different prognosis, researchers wrote in the American Journal of Roentgenology. Understanding these two criteria as they apply to cancers presenting as ground glass nodules (GGNs) may go a long way toward advancing patient treatment.

“The ability to preoperatively predict histopathologic subtypes and growth patterns of lung adenocarcinoma according to the noninvasive imaging characteristics of GGNs will help in development of a reasonable treatment plan and effective prognosis of lung adenocarcinoma,” lead author Xiaoliang Shao, with Soochow University in Changzhou, China, and colleagues wrote.

Typically, adenocarcinoma lesions present as focal ground glass nodules on CT scans, making it difficult for radiologists to accurately diagnose and classify them by subtype. Researchers sought to add FDG-PET to the imaging protocol to get a better understanding of such nodules.

To do so, they gathered retrospective PET/CT data on resected ground glass nodules from patients with stage IA lung adenocarcinoma, which indicates the cancer has not yet spread to the lymph nodes. Shao et al. evaluated the PET maximum standardized uptake value combined with high-resolution imaging indicators that could be used to predict cancer subtype and development patterns.

Maximum uptake was much higher in nodules considered invasive on CT scans. The diameter of the nodule and attenuation value differential between ground glass features and neighboring lung tissue were both independent predictors of how much contrast nodules would uptake.

Essentially, the team agreed that FDG PET/CT was useful for predicting invasive cancer subtypes, but it did little to help identify growth patterns. They also noted that using PET and CT together was more accurate than utilizing each modality independently.

“FDG PET can be used to predict the histopathologic subtypes and growth patterns of early lung adenocarcinoma,” they concluded. “Combined with high-resolution CT, it has value for predicting invasive histopathologic subtypes but no significance for predicting invasive growth patterns.”