Introduction:
The lungs are organs involved in respiration and the exchange of gases. The growth of an abnormal mass of cells or tissues in the lungs is referred to as lung cancer. It is one of the leading causes of death worldwide. People who smoke cigarettes are at the highest risk of developing lung cancer. Broadly, lung cancers are classified into small cell lung cancer (common in heavy smokers) and non-small cell lung cancer. For example, bronchioalveolar carcinoma is an uncommon non-small cell lung cancer.
What Is Bronchioloalveolar Carcinoma?
Bronchioloalveolar carcinoma (BAC) is a rare kind of adenocarcinoma (lung cancer). About 2.6 to 4.3 % of all lung malignancies are caused by BAC. BAC is a non-small cell lung cancer subtype that manifests in the alveoli, or tiny air sacs, on the lungs' periphery. BAC generally develops along alveolar walls at the lung periphery without harming the lung parenchyma, which is part of the lung responsible for gas transmission. It may develop from a previously stable scar and is frequently multicentric (having more than one center). In contrast to other types of lung cancer, which can frequently spread to the lining of the lungs and other locations in the body, BAC spreads largely within the lungs themselves.
The term "the mystery of lung cancer" refers to bronchioalveolar carcinoma because of its unpredictability and ability to develop into either a slowly growing, progressive tumor or a rapidly growing cancer. BAC was once used to describe a certain subtype of lung adenocarcinoma. Since then, it has been categorized as a kind of lung cancer. However, significantly less is known about this cancer as it is rare. Understanding bronchioalveolar carcinoma is particularly important, as the occurrence is increasing in young women without a smoking history.
What Causes Bronchioloalveolar Carcinomas?
The exact reason behind the pathogenesis of bronchioalveolar carcinoma is not known. However, this cancer is more likely to affect Asians, women, and non-smokers.
What Are the Types of Bronchioloalveolar Carcinomas?
There are two main types of bronchioloalveolar carcinoma,
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Non-mucinous bronchioloalveolar carcinoma is a variant that is more common and affects smokers.
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Mucinous bronchioloalveolar carcinoma refers to bronchioloalveolar carcinomas that produce mucous that expels sputum or mucous. The mucinous variant is common in non-smokers.
What Are the Symptoms of Bronchioloalveolar Carcinomas?
The symptoms of bronchioalveolar carcinoma are similar to those of other lung cancers. However, the course of BAC is unpredictable and can be mistaken for pneumonia or other lung conditions.
The common symptoms of bronchioloalveolar carcinoma are:
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Cough that does not resolve.
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Blood while coughing.
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Pain in the chest.
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Difficulty breathing and shortness of breath.
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Productive cough (sputum or mucus).
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Profound fatigue.
How Is Bronchioloalveolar Carcinoma Diagnosed?
Bronchioalveolar carcinoma is diagnosed after evaluating the patient's medical history, signs and symptoms, laboratory tests, and advanced scanning.
1. Physical Examination - The physician will ask for the medical history and evaluate the risk factors. Abnormal lung sounds, enlarged lymph nodes, and clubbing of the fingers (bulged or chubby nail beds) indicate lung disorders.
2. Advanced Imaging - This includes chest X-rays, CT (computed tomography), MRI (magnetic resonance imaging), and PET (positron emission tomography) scans. Combined PET and CT scans help diagnose the tumor. For example, the findings might show an abnormal cell mass in the alveoli.
3. Lung Biopsy - A tissue sample is removed from the suspected lesion and studied under the microscope. The cells are studied for changes in their growth pattern and division. If cancer has spread, other biopsies may be needed. The biopsy tissue can be removed by:
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FNAC (Fine Needle Aspiration Cytology): A tissue sample is taken by inserting a needle through the skin into the lesion.
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Bronchoscopy: A telescope-like device is inserted into the lungs to visualize the lesion. The procedure is carried out under general anesthesia, and a tissue sample is taken for biopsy.
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Endobronchial Ultrasound: It is a new cancer diagnosis technique where an ultrasound probe is inserted into the lungs.
4. Laboratory Tests -
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Pulmonary Function Tests: It is used to test lung capacity and helps to determine the interference of cancer with breathing.
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Blood Tests: Chemicals called tumor markers are found at high levels and are detected in the blood. Tumor markers can indicate cancer and metastasis.
5. Sputum Cytology - Involves the study of mucus collected from the lungs under a microscope. However, the test is not always accurate, and some cancer cells can go missing during the procedure.
6. Genetic Testing - It is also called molecular profiling and is used to understand the molecular changes in cancer cells.
What Is the Treatment of Bronchioloalveolar Carcinomas?
1. Surgery: Surgical resection is undergone when there is a single tumor. Surgery with adjuvant chemotherapy is still controversial and needs further evaluation.
2. Chemotherapy: Uses specific medications to target cancer cells and interfere with their growth. However, the tumor is less sensitive to chemotherapy, but it can be given as adjuvant therapy.
3. Lung Transplant: It is being considered as an additional treatment as it offers long-term survival.
4. Targeted Therapy: New targeted therapies for lung cancer, which are medicines tailored to target particular gene alterations inside a particular tumor, have shown some promise in treating BAC. Because of this, individuals with BAC are excellent candidates for tumor genetic testing.
What Is the Differential Diagnosis of Bronchioloalveolar Carcinoma?
With identical histological characteristics but a considerably better prognosis, the differential diagnosis of bronchioloalveolar cancer includes:
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Type 2 pneumocyte hyperplasia
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Atypical adenomatous hyperplasia
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A sclerosing hemangioma
Differentiation is helped by immunophenotyping.
What Is the Prognosis of Bronchioloalveolar Carcinomas After the Treatment?
The survival rate for bronchioalveolar carcinoma is better than other non-small cell lung cancers. If this cancer is detected early and if there is a single mass, then the survival rate is reasonable. According to one study report, the five-year survival rate of tumors less than three centimeters was 100 % after the surgery. Survival rates vary depending on the stage of cancer, presence of multiple masses, involvement of lymph nodes, metastasis, etc.
Conclusion:
Bronchioalveolar or bronchoalveolar carcinoma (BAC) is an uncommon type of lung cancer. Symptoms of bronchioalveolar carcinoma include persistent cough, blood while coughing, breathing difficulties, chest pain, etc. If this cancer is detected early and if there is a single mass, then the survival rate is reasonable. It varies depending on the stage of cancer, presence of multiple masses, involvement of lymph nodes, metastasis, etc. Nevertheless, the survival rate for bronchioalveolar carcinoma is better compared to other non-small cell lung cancers.
