What is the most common type of lung cancer?

Adenocarcinoma falls under non-small cell lung cancer and actually stands as the most common form. It makes up about 40% of NSCLC cases and roughly 30% of all lung cancer diagnoses.

Which type of lung cancer is more serious?

Small-cell lung cancer is generally more aggressive because it grows and spreads much faster. However, both types are serious, and outcomes depend heavily on the stage at diagnosis and the treatment approach.

Can non-smokers get small-cell lung cancer?

SCLC is very strongly related to tobacco smoking and is rare in people who have never smoked. Non-smokers who develop lung cancer are far more likely to have NSCLC, particularly adenocarcinoma.

What is the difference in treatment between SCLC and NSCLC?

SCLC is typically treated with chemotherapy and radiation. NSCLC has a broader range of options, including surgery, targeted therapy, and immunotherapy, depending on the stage and genetic profile of the tumour.

Why does the subtype of lung cancer matter?

Each subtype behaves differently, spreads at different rates, and responds to different treatments. Knowing the exact type and, for NSCLC, the specific genetic mutations involved, allows doctors to personalise treatment and significantly improve outcomes.

Types of Lung Cancer: Small Cell vs Non-Small Cell

What Are the Types of Lung Cancer?

Lung cancer is divided into two main types: small-cell lung cancer (SCLC) and non-small-cell lung cancer (NSCLC). They differ in how they grow, where they start, how they spread, and how they are treated. Knowing which type you have is one of the most important factors in determining the right treatment plan.

What Is Non-Small Cell Lung Cancer (NSCLC)?

Most lung cancers fall under non-small cell. As per research, 85% of lung cancer cases are non-small cell lung cancer. It is called non-small cell because, under a microscope, the cancer cells appear larger than those of small cell lung cancer. NSCLC typically grows more slowly than SCLC and, in its early stages, may produce few or no symptoms. There are three main subtypes of NSCLC, each with different characteristics and treatment responses.

Adenocarcinoma

Adenocarcinoma is the most common type of lung cancer overall, accounting for around 40% of all NSCLC cases. It develops in the mucus-producing glands in the outer regions of the lungs, in cells that normally secrete mucus.

Unlike many other lung cancers, adenocarcinoma is the type most commonly found in non-smokers, women, and younger patients. It is also strongly associated with specific genetic mutations such as EGFR, ALK, and ROS1, which can be targeted by precision therapies. Biomarker testing at diagnosis is especially important for this subtype.

Squamous Cell Carcinoma

Squamous cell carcinoma (SCC) accounts for around 30% of NSCLC cases. It develops in the flat cells lining the airways, typically in the central part of the lung near the bronchi. This type is strongly linked to smoking history.

Squamous cell carcinoma grows more slowly than adenocarcinoma and is less likely to carry the targetable genetic mutations associated with adenocarcinoma.

Large-Cell Carcinoma

Large-cell carcinoma, sometimes called large-cell undifferentiated carcinoma, accounts for approximately 10 to 15% of all NSCLC diagnoses. Unlike the other subtypes, it does not resemble squamous or glandular cells under a microscope. It can begin in any part of the lung. It grows and spreads more rapidly than other NSCLC subtypes.

What Is Small Cell Lung Cancer (SCLC)?

Small-cell lung cancer represents fewer than 20% of all lung cancer cases, but it is significantly more aggressive than NSCLC. SCLC typically starts in the bronchi, the airways leading from the trachea into the lungs, and spreads rapidly to the lymph nodes and other parts of the body.

Because of how quickly it spreads, SCLC is frequently diagnosed at an advanced stage. By the time symptoms appear, the cancer has often already reached distant organs such as the brain, liver, or bones.

SCLC is almost exclusively caused by tobacco smoking and is rare in people who have never smoked.

Types of SCLC

SCLC is divided into two categories:

Small cell carcinoma: The most common type. Under a microscope, the cells appear flat and grain-like, often compared to oat grains. This is why it is sometimes called oat cell cancer.
Combined small cell carcinoma: Refers to tumours that contain a mixture of small cell carcinoma cells and a small number of non-small cell lung cancer cells.

Key Differences: SCLC vs NSCLC

How Are They Treated Differently?

Because SCLC spreads so quickly, surgery is rarely a viable option. It is generally treated with a combination of chemotherapy and radiation therapy. It tends to respond well to chemotherapy initially, but recurrence is common.

NSCLC offers more treatment options depending on the stage and subtype. These include surgery (particularly in early stages), radiation therapy, chemotherapy, targeted therapy based on genetic mutations, and immunotherapy. Targeted therapies have dramatically improved outcomes for NSCLC patients whose tumours carry specific, treatable mutations.

Conclusion

Recognizing the differences between small-cell and non-small-cell lung cancer is important for making the right diagnosis and treatment choices. Each type grows, spreads, and reacts to treatment in its own way. Early diagnosis and proper classification can help guide an effective management plan. With advances in targeted therapies and immunotherapy, outcomes for many patients with lung cancer continue to improve. If you have concerns about lung cancer symptoms or risk factors, feel free to connect with our pulmonologist online.