Bronchioloalveolar carcinoma

Bronchioloalveolar carcinoma (BAC) is a unique subtype of non-small cell lung cancer (NSCLC) that originates from the epithelial cells of the terminal bronchioles and alveoli. It is characterized by its distinct growth pattern and clinical behavior, which differentiates it from other forms of NSCLC.

Epidemiology

Bronchioloalveolar carcinoma accounts for approximately 2-6% of all lung cancers. It is more common in women and non-smokers, and its incidence appears to be increasing worldwide.

Pathogenesis

The pathogenesis of BAC is not fully understood. However, it is believed to arise from clonal expansion of mutated alveolar type II cells or Clara cells. These cells have the ability to differentiate into either type I pneumocytes or type II pneumocytes, which are the primary cell types affected in BAC.

Clinical Features

Patients with BAC often present with non-specific symptoms such as cough, dyspnea, and weight loss. In some cases, the tumor may be discovered incidentally on imaging studies performed for other reasons. The disease is often advanced at the time of diagnosis, with many patients having widespread disease in the lungs and other organs.

Diagnosis

The diagnosis of BAC is made based on the histological examination of a lung biopsy specimen. The characteristic feature of BAC is the presence of tumor cells growing along the alveolar septa without invasion into the lung parenchyma.

Treatment

The treatment of BAC depends on the stage of the disease at the time of diagnosis. For localized disease, surgical resection is the treatment of choice. For advanced disease, systemic therapy with chemotherapy or targeted therapies may be used.

Prognosis

The prognosis of BAC is generally better than that of other forms of NSCLC, with a 5-year survival rate of approximately 50% for localized disease. However, the prognosis is poor for advanced disease, with a median survival time of less than one year.