Types of Lung Cancer: Common & Rare

Dr.Parveen Jain, 5 mins read

Cancer is a disease in which cells divide and multiply abnormally and uncontrollably. When the cancer cells begin in the lungs, it is called lung cancer.

Smoking is the biggest culprit of lung cancer, though this disease can also occur in those who have never smoked. Doctors classify lung cancer into various types based on the appearance of cancer cells under a microscope and the kind of cells it develops in.

In this blog, we’ll discuss the common and rare types of lung cancers. 

Common Types of Lung Cancer

Non-small Cell Lung Cancer (NSCLC)

NSCLC accounts for almost 80% to 85% of lung cancers. Smoking is the major risk factor for all types of non-small cell lung cancer. Its cells appear large under a microscope and usually comes under one of the following subcategories:

• Squamous cell carcinoma, often develops in the bronchi (the large tube that connects the windpipe to the lungs) near the middle of the lungs.
• Lung adenocarcinoma begins in the cells that produce mucus. This is the most commonly found lung cancer in non-smokers.
• Adenosquamous carcinoma develops in the mixture of mucus-producing cells and squamous cells.
• Large cell carcinoma can be described as a group of cancers in which cells appear large and abnormal.

Small Cell Lung Cancer (SCLC)

About 10% to 15% of all lung cancers are SCLCs. They develop and spread more quickly than other types of lung cancers. This type of cancer almost exclusively occurs in smokers. SCLC has two types:

• Small cell carcinoma cells appear small under a microscope.
• Combined non small cell and small cell carcinoma begins in lung tissue and contains mixed features of SCLC and NSCLC.

Rare Types of Lung Cancer

Carcinoid Tumours or Neuroendocrine tumors (NET)

Although it usually appears in the Pancreas and intestinal tract, it can sometimes begin in the lungs. Carcinoid tumours can be typical or well differentiated NET (grow slowly and don’t often spread out of the lungs) and atypical or moderately differentiated NET (grow quickly and more likely to spread out of the lungs). Almost 9 out of every ten lung carcinoids are typical carcinoids.

Pancoast Tumour or Superior Sulcus Tumor

Pancoast tumor or superior sulcus tumor usually begins at the apex of the lungs and can invade the nearby tissue or nerves leading to development of shoulder pain, vertebral pain or rib pain. Pancoast tumor diagnosis is often delayed as it doesn’t show the classic symptom of lung cancer, i.e., cough, shortness of breath.

Mesothelioma

It is a type of cancer which develops in the tissue covering the lungs and under surface of chest wall. It accounts for almost 5% of all lung cancers and they are usually associated with asbestos exposure. 

Chest Wall Tumours

Chest wall tumors are the cancers that arise from the structures of chest wall including cartilages, soft tissue and bones. They can be cancerous or non-cancerous.As per a study, more than half of the chest wall tumors are cancerous. This type of lung cancer can affect any age group. 

Pulmonary Sarcomatoid Carcinoma

It is a rare and aggressive subtype of NSCLC. It develops in the epithelial cells that line your lungs. Almost 0.1% to 0.4% of lung cancers are pulmonary sarcomatoid carcinoma. 

Adenoid Cystic Carcinoma of the Lung

It is a slow-growing and low-grade malignancy that forms in glands in your lungs. Adenoid cystic carcinoma is diagnosed at a higher clinical stage and is usually difficult to cut out because of its central location. 

Lymphoma

Lymphoma is a rare type of cancer that begins in the lymphatic system and includes Hodgkin’s and non-Hodgkin’s lymphoma. Sometimes, it also develops in the lungs.

Lung Sarcomas

A sarcoma is a group of cancers that develops in the mesenchymal tissue of the lungs. It constitutes only 0.013% to 1.1% of all lung cancers. 

Treatment of Lung cancer

Treatment of Non-Small cell lung cancer

Treatment of NSCLC depends on the stage of the cancer: 

• Stage I & II: 

1. Surgery: is the most common and effective modality of treatment. Part of diseased lung (Lobectomy) or complete lung (Pneumonectomy) is removed.
2. Radiation therapy: is used in those patients who are not medically fit for surgery or who are not willing for surgery. Radiation therapy is also indicated in some patients in post-operative phase, if some part of tumor was left behind.
3. Chemotherapy: usually required after surgery according to the size of the tumor or nodal status of the tumor.
4. Targeted therapy: is sometimes used to treat specific NSCLC types with some genetic aberration.
5. Immunotherapy: is used in some NSCLCs as a pre-operative therapy or postoperative therapy.

• Stage III: Usually stage III NSCLC requires combined modality treatment where combinations of Surgery, Radiotherapy and Systemic therapies (Chemotherapy, Immunotherapy, targeted therapy) are used.
• Stage IV: Usually are treated with systemic therapies (Chemotherapy, Immunotherapy, targeted therapy) only. Sometimes Surgery or radiation therapy are used to palliate the symptoms.

Treatment of Small cell lung cancer

Small cell lung cancer is staged differently than NSCLC. There are only 2 stages in SCLC: limited stage (potentially curable stage) and Extensive stage (where the disease has spread to non regional lymph nodes and distant organs). 

• Limited-stage disease: Usually treated with combination of chemotherapy and radiotherapy. There are minority of patients with very early stage of disease, where surgery can also be considered.
• Extensive stage disease: Usually treated with systemic therapies (Chemotherapy and Immunotherapy). Surgery or radiation therapy are sometimes used to palliate the symptoms.

Also, Read: All About Lung Cancer