Minimally invasive adenocarcinoma of the lung (MIA) is defined as a small (â¤3 cm), solitary tumour with predominant alveolar epithelial appearance (lepidic growth), as in situ adenocarcinoma of the lung, with a zone of focal invasion of the stroma with a size inferior to 5 mm. For MIAâÂÂas with adenocarcinoma in situâÂÂ, the prognosis is near 100% survival.