Lung cancer remains the leading cause of cancer-related deaths and the second most diagnosed cancer in the United States. Among the various types of lung cancer, adenocarcinoma is the most common. Specifically, adenocarcinoma with a lepidic growth pattern is characterized by tumor cells proliferating along the surface of intact alveolar walls, without stromal or vascular invasion, as assessed pathologically.

The International Association for the Study of Lung Cancer, American Thoracic Society, and European Respiratory Society (IASLC/ATS/ERS) provide classification criteria for subtyping adenocarcinoma with a lepidic growth pattern. This classification is based on tumor size and the presence or absence of stromal invasion. Adenocarcinoma in situ (AIS) is defined as having an entirely lepidic growth pattern and measuring greater than 0.5 cm but less than or equal to 3 cm. Minimally invasive adenocarcinoma (MIA) is identified as measuring less than or equal to 3 cm with stromal invasion of 0.5 cm or less. Lepidic predominant adenocarcinoma (LPA) refers to tumors with a lepidic-predominant growth pattern measuring greater than 3 cm, those with more than 0.5 cm of invasion, or those exhibiting lymphovascular or pleural invasion of any size.

Research indicates that AIS and MIA have a favorable prognosis, with nearly a 100% 5-year cancer-specific survival rate. In contrast, LPA presents a cancer-specific survival rate ranging from 85.7% to 100% following surgical resection.