Lung Cancer: An Overview

What it is

Lung cancer is a malignancy that arises from the cells lining the airways and gas-exchange tissue of the lung. It is not a single disease but a family of tumors with distinct biology, growth patterns, and treatment implications. The broadest and most clinically useful division is between non-small cell lung cancer (NSCLC) — which includes adenocarcinoma, squamous cell carcinoma, and large cell neuroendocrine carcinoma — and small cell lung carcinoma (SCLC), an aggressive neuroendocrine subtype. A spectrum of less common entities, including carcinoid tumors and pre-invasive lesions such as adenocarcinoma in situ, rounds out the picture. These distinctions matter because they shape how the disease behaves and which therapies are considered.

How common it is

Lung cancer is the third most common cancer diagnosis in the United States, accounting for roughly 10.8% of new cancer cases, with about 229,410 new cases of lung and bronchus cancer projected for 2026 [2]. The age-adjusted incidence rate is approximately 47.2 per 100,000 per year (2019–2023), and the lifetime risk is about 1 in 16 overall — though this figure varies sharply with smoking history and should not be read as a uniform risk [1].

The trend is encouraging. Incidence has been falling about 1.9% per year (2014–2023), tracking the long decline in tobacco use [1]. Despite this, lung cancer remains the leading cause of cancer death, with about 124,990 deaths projected for 2026 [2]. Mortality, however, is dropping faster than for any other major cancer — roughly 4.1% per year (2015–2024) — reflecting both fewer cases and better treatment [1].

Who's at risk

Risk factors fall into modifiable and non-modifiable categories.

Modifiable:

• Tobacco smoking is the dominant cause; risk scales with cumulative exposure (pack-years), and secondhand smoke also contributes [1].
• Radon, a naturally occurring indoor gas, is the second leading cause [1].
• Occupational and environmental carcinogens, including asbestos, diesel exhaust, arsenic, and certain metals, raise risk [1].

Non-modifiable:

• Age — lung cancer is most frequently diagnosed between 65 and 74 [1].
• Prior lung disease or family history, including COPD, pulmonary fibrosis, and a first-degree family history [1].
• A never-smoker subset exists — a meaningful minority of cases, often adenocarcinomas driven by EGFR or ALK alterations, more common in women and people of East Asian ancestry [1].

It is worth emphasizing that lung cancer is not exclusively a smoker's disease; never-smokers can and do develop it, which is one reason biomarker testing has become central to evaluation.

How it's found

The principal screening modality is annual low-dose CT (LDCT). The US Preventive Services Task Force recommends annual LDCT for adults aged 50–80 with a 20 pack-year smoking history who currently smoke or quit within the past 15 years [3]. This is presented here as a neutral summary of published guidance, not as a recommendation directed at any individual reader; eligibility and personal circumstances are matters for a clinician to discuss. Notably, screening uptake remains low relative to the eligible population, and eligibility criteria have broadened over time [1].

Many lung cancers are still diagnosed at an advanced stage, in part because early disease is often silent. Common presentations include persistent cough, coughing up blood (hemoptysis), shortness of breath, chest pain, and unintentional weight loss — though an increasing number of tumors are now found incidentally on imaging performed for other reasons [1].

Outlook

An essential caveat: the survival figures below are population-level statistics drawn from large registries. They describe groups of people diagnosed in the past, not the future of any single individual. A person's actual outlook depends on tumor biology, stage, overall health, the specific therapies available to them, and factors no summary statistic can capture.

With that framing, the overall five-year relative survival is approximately 28% — historically low, but improving [1]. Survival is strongly stage-dependent (2016–2022 data):

• Localized disease (confined to the lung): ~65% [1]
• Regional disease (spread to nearby nodes/structures): ~37% [1]
• Distant (metastatic) disease: ~10% [1]

The evidence suggests these numbers are moving in a favorable direction. Survival for metastatic disease rose from roughly 2% to about 10%, attributed to LDCT screening catching disease earlier, more accurate staging, and the advent of targeted and immunotherapy approaches [1]. This is an area of active and rapid change, and historical survival statistics likely understate what is achievable for patients diagnosed today.

How it's diagnosed and classified

Diagnosis rests on tissue: a biopsy confirms malignancy, and pathology assigns the tumor to a category — most commonly adenocarcinoma, squamous cell carcinoma, small cell carcinoma, large cell neuroendocrine carcinoma, carcinoid tumors, or pre-invasive lesions such as AIS/MIA. This histologic classification, combined with anatomic staging, frames every subsequent decision. The diagnostic pillar of this site explores how pathologists and radiologists arrive at these distinctions.

How treatment is guided

Beyond histology, modern lung cancer care increasingly depends on molecular biomarkers, which can identify eligibility for specific drug classes. Recurring testing themes include EGFR, ALK, ROS1, BRAF V600E, KRAS G12C, MET exon 14 skipping, RET, NTRK, and ERBB2/HER2 alterations, along with PD-L1 expression and emerging markers such as TROP-2 and ctDNA-guided monitoring. These biomarkers help match a tumor's biology to a category of therapy; they do not, in themselves, constitute treatment advice — that determination always belongs to a patient and their care team. The biomarker pillar of this site examines each of these in detail.

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References

1. National Cancer Institute. SEER Cancer Stat Facts (SEER*Explorer). surveillance.cancer.gov / seer.cancer.gov/statfacts. 2026 release (2019–2023 incidence; 2020–2024 mortality; 2016–2022 survival).
2. Siegel RL, Kratzer TB, Wagle NS, Sung H, Jemal A. Cancer statistics, 2026. CA Cancer J Clin. 2026. doi:10.3322/caac.70043.
3. US Preventive Services Task Force. Lung Cancer: Screening (2021 Recommendation). uspreventiveservicestaskforce.org. 2021.