What are the radiologic findings predictive of indolent lung adenocarcinoma?

Objective: Small pulmonary nodules are often followed up. This study aimed to establish radiographic criteria with which to accurately and reproducibly predict indolent cancers including adenocarcinoma in situ.

Methods: We examined correlations between pre-operative factors and surgical outcomes, including pathological findings and prognosis among 609 patients with clinical Stage IA lung adenocarcinoma that had been completely resected at multiple institutions. Indolent cancers were defined as tumors without lymphatic, blood vessel, pleural invasion or lymph node involvement (LY0V0PL0N0) regardless of stromal invasion.

Results: Pathological assessments of specimens of 35 of 85 (41%) pure ground glass opacity tumors including 3 (23%) of 13 pure ground glass opacity tumors ≤ 1 cm, revealed partially invasive components. Receiver operating characteristic curves for LY0V0PL0N0 revealed solid tumor size ≤ 6 mm on high-resolution computed tomography or maximum standardized uptake values ≤ 0.6 on 2-[18F]fluoro-2-deoxy-d-glucose positron emission tomography/computed tomography as radiographic indolent tumor criteria for predicting indolent tumors. Among 216 (35.5%) of 609 patients who met these criteria, none developed recurrence over a median follow-up of 41.6 months.

Conclusions: Pure ground glass opacity lesions on high-resolution computed tomography could pathologically include invasive components and would not correspond to adenocarcinoma in situ. Solid tumor size on high-resolution computed tomography and maximum standardized uptake values on positron emission tomography/computed tomography can predict indolent LY0V0PL0N0 lung tumors that can be followed up.