Types of Lung Cancer: Comprehensive Guide to Common and Rare Subtypes

Learn about the diverse types of lung cancer, including common and rare forms, their characteristics, and important diagnostic insights.

By Medha deb

Created on Sep 25, 2025

Types of Lung Cancer

Lung cancer is one of the most prevalent and deadly cancers worldwide. Understanding the different types of lung cancer is essential for diagnosis, treatment planning, and prognosis. This guide explores the key categories and subtypes of lung cancer, highlighting both common and rare forms.

Overview: Classification of Lung Cancer

Doctors classify lung cancer into different types based on how the cancer cells appear under a microscope and the origin of those cells. The main classification includes:

Non-small cell lung cancer (NSCLC)
Small cell lung cancer (SCLC)
Rare and unusual types

Each category encompasses further subtypes with distinct characteristics and implications for treatment.

Common Types of Lung Cancer

More than 95% of lung cancers are classified as either non-small cell or small cell lung cancer. The following outlines the subtypes and features of each category.

Non-Small Cell Lung Cancer (NSCLC)

NSCLC accounts for approximately 80–85% of all lung cancer cases. It typically grows more slowly and spreads less aggressively compared to small cell lung cancer. Key subtypes include:

Squamous Cell Carcinoma – Develops in the squamous cells lining the airways, especially the bronchi (central air passages). It is closely linked to a history of smoking and tends to occur in the central regions of the lungs.
Adenocarcinoma – The most common form of NSCLC and lung cancer overall. It starts in cells that produce mucus and usually arises in the outer parts of the lung. Adenocarcinoma can occur in both smokers and non-smokers.
Adenosquamous Carcinoma – Contains features of both squamous cells and mucus-producing glandular cells. This subtype is relatively rare and may share characteristics of both parent cell types.
Large Cell Carcinoma – Comprises a group of NSCLC tumors that do not fit clearly into other NSCLC subtypes. Large cell cancers tend to grow and spread quickly and can appear in any part of the lung.

Table: Major NSCLC Subtypes

Subtype	Origin Cell Type	Common Location	Prevalence (% NSCLC)
Squamous Cell Carcinoma	Squamous epithelial cells	Central airways (bronchi)	~25%
Adenocarcinoma	Mucus-producing glandular cells	Peripheral lung tissue (outer regions)	~40%
Large Cell Carcinoma	Undifferentiated cells	Any lung region	~10%
Adenosquamous Carcinoma	Mixed squamous and glandular cells	Varies	Rare

Risk Factors: Smoking is the primary risk factor for NSCLC, but environmental exposures, genetic influences, and prior lung disease can also play a role.

Small Cell Lung Cancer (SCLC)

Comprising about 15–20% of lung cancers, small cell lung cancer is less common but generally more aggressive than NSCLC. SCLC often spreads rapidly to other parts of the body and is strongly associated with cigarette smoking. The main forms include:

Small Cell Carcinoma (Oat Cell Carcinoma) – The classic form, characterized by small, round cells under the microscope.
Combined Small Cell Carcinoma – Contains a mixture of small cell and non-small cell carcinoma characteristics within the tumor. This type can exhibit unique growth and treatment behaviors.

Symptoms of SCLC often arise only after the cancer has already spread, which diminishes the effectiveness of treatment compared to localized cancers. Despite high initial sensitivity to chemotherapy and radiation, SCLC has a high recurrence rate.

Lung Nodules and Metastasized Cancers

Lung Nodule – An abnormal mass of tissue in the lung, often discovered incidentally during imaging. Most nodules are benign but require evaluation to exclude cancer.
Metastasized Cancers – These are cancers that originated in other organs and have spread to the lungs. While they may form lung tumors, they are not classified as primary lung cancers but rather as metastatic cancer from their site of origin.

Rare Types of Lung Cancer

Less than 5% of lung cancers are classified as rare types. These include a variety of tumors arising from different cell types or regions in and around the lungs. Highlights of the rare forms include:

Carcinoid Tumors – Slow-growing tumors that develop from neuroendocrine cells responsible for hormone production. They are often less aggressive than NSCLC or SCLC and are sometimes found incidentally. Carcinoid tumors can be classified as typical or atypical based on their cellular features and growth patterns.
Pancoast Tumor – A tumor that develops at the apex (top) of the lung. It can invade nearby tissues such as the chest wall or nerves, causing unique symptoms like shoulder pain or muscle weakness in the arm.
Mesothelioma – A rare and aggressive cancer arising from the mesothelial cells lining the lungs (the pleura). Mesothelioma is closely linked to a history of asbestos exposure and may develop decades after initial contact.
Chest Wall Tumors – Tumors that originate on the wall of the chest cavity, which may be benign or malignant. Malignant tumors are often aggressive and may invade the underlying lung or ribs.
Pulmonary Sarcomatoid Carcinoma – A very rare form accounting for only 0.1–0.4% of all lung cancers. It displays features of both carcinoma and sarcoma, involving epithelial and mesenchymal cell origins. This cancer is generally aggressive and resistant to conventional treatments.
Adenoid Cystic Carcinoma of the Lung – Typically found in the salivary glands, but can also arise in the airways of the lung. Known for slow growth and a tendency for local invasion.
Lymphoma – Rarely, lung tissue can be the primary site for lymphoma, mainly mucosa-associated lymphoid tissue (MALT) lymphoma.
Lung Sarcomas – Tumors originating from the mesenchymal tissues (the cells that form connective tissue) within the lungs. These are very rare and require specialized treatment.
Mediastinal Tumor – Tumors arising in the mediastinum (the area between the lungs), which can compress nearby organs and cause various symptoms based on location and size.

Other Lung-Related Malignancies

Some malignancies may develop in or around the lungs, even if they are not classified strictly as lung cancer. These include:

Lymphomas – Affecting the lymphatic tissues in or near the lungs.
Sarcomas – Arising from connective or soft tissue components.
Pleural tumors – Such as mesothelioma, involving the lining of the lung.

Key Differences Between NSCLC and SCLC

Feature	Non-Small Cell Lung Cancer (NSCLC)	Small Cell Lung Cancer (SCLC)
Prevalence	~80–85% of cases	~15–20% of cases
Growth Rate	Relatively slow	Very rapid
Spread (Metastasis)	Less aggressive	Highly aggressive, early spread
Main Risk Factor	Smoking, environmental, genetic	Strongly tied to smoking
Treatment Sensitivity	More varied, often surgery +/− chemo/radiation	Chemo and radiation, surgery rare

Diagnosis and Staging

Diagnosing the type of lung cancer involves a combination of:

Imaging studies, such as chest X-ray, CT scan, and PET scan
Laboratory tests, including blood tests and tumor markers
Bronchoscopy and tissue biopsy (to examine cell type under a microscope)
Molecular and genetic tests in select cases to identify mutations or biomarkers guiding targeted therapies

Staging: Cancer is staged based on tumor size, lymph node involvement, and metastasis. Accurate staging guides treatment choices and prognosis.

Risk Factors for Lung Cancer

The primary risk factors for all types of lung cancer include:

Smoking (cigarettes, cigars, pipes)
Exposure to secondhand smoke
Occupational exposures (asbestos, radon, arsenic)
Family history of lung cancer
Recurrent lung infections or chronic lung diseases
Environmental pollution

Frequently Asked Questions (FAQs)

Q: What are the main types of lung cancer?

A: The two major types of lung cancer are non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). Less than 5% of lung cancers are rare subtypes, such as carcinoid tumors and mesothelioma.

Q: Are all lung nodules cancerous?

A: No, most lung nodules are benign (non-cancerous). However, they require medical evaluation to rule out malignancy.

Q: Can non-smokers get lung cancer?

A: Yes. While smoking is the leading risk factor, non-smokers can develop lung cancer due to genetic factors and environmental exposures like radon or pollution.

Q: Are rare lung cancers treated differently?

A: Yes. Rare forms, such as mesothelioma or carcinoid tumors, may require specialized diagnostic techniques and tailored treatment approaches different from standard NSCLC or SCLC protocols.

Q: How is lung cancer staged?

A: Lung cancer staging is based on tumor size, lymph node involvement, and whether cancer has metastasized (spread) to other organs. Staging affects treatment strategy and prognosis.

Conclusion

Lung cancer encompasses a diverse group of diseases, with most cases classified as non-small cell or small cell types, each with distinct characteristics and treatment pathways. Accurate classification, prompt diagnosis, and tailored treatments are vital for improving patient outcomes, especially in rarer forms. Awareness and early medical consultation play a key role in effective management of all types of lung cancer.

References

Author

medha deb

Medha Deb is an editor with a master's degree in Applied Linguistics from the University of Hyderabad. She believes that her qualification has helped her develop a deep understanding of language and its application in various contexts.

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