Biophoto Associates/Science Source
Bronchioalveolar cell carcinoma (BAC) is a variant of non–small cell lung cancer (NSCLC) that, in recent years, has received a new identity in some of the literature. Adenocarcinoma in situ (AIS) and minimally invasive adenocarcinoma (MIA) are relatively new entities that in some published literature have replaced the term BAC. The National Comprehensive Cancer Network recognizes these terms. AIS is defined as a localized adenocarcinoma of < 3 cm that exhibits a lepidic growth pattern, with neoplastic cells along the alveolar structures but without stromal, vascular, or pleural invasion. MIA refers to small, solitary adenocarcinomas < 3 cm with either pure lepidic growth or predominant lepidic growth with ≤ 5 mm of stromal invasion. BAC has unique epidemiologic, pathologic, and clinical features compared with other NSCLC subtypes. For example, although it is smoking-related, the relationship of BAC to smoking is less strong than with other types of NSCLC. About a third of patients with BAC are never-smokers.
There are also some unique radiographic features — its presentation may be confused with pneumonia or other inflammatory conditions in the lung, and only after a patient does not improve after a course of antibiotics should a diagnosis of BAC be considered. Unlike other types of lung cancer where chemotherapy may be the first plan of attack, surgery is often the first choice for treating BAC, particularly when there is no mediastinal node involvement (10%-25% of cases) or distal metastases (5% of cases). BAC usually harbors EGFR mutation. It is responsive to new targeted therapies for lung cancer, particularly osimertinib, afatinib, erlotinib, and gefitinib. Thus, people with BAC are good candidates for genetic testing.
Karl J. D'Silva, MD, Clinical Assistant Professor, Department of Medicine, Tufts University School of Medicine, Boston; Medical Director, Department of Oncology and Hematology, Lahey Hospital and Medical Center, Peabody, Massachusetts
Karl J. D'Silva, MD, has disclosed no relevant financial relationships.