Lung Cancer: Types, Diagnosis and Treatment

Lung Cancer: Types, Diagnosis and Treatment

Lung cancer is the leading cause of cancer death worldwide overall; WHO estimated about 1.8 million deaths in 2022. Approximately 85% of cases are linked to tobacco smoking, but the disease also affects non-smokers, and its rate in never-smokers is rising.

Types of Lung Cancer

Non-Small Cell Lung Cancer (NSCLC)

Non-small cell lung cancer accounts for approximately 85% of all lung cancers. It grows more slowly than small cell lung cancer and is broadly divided into three subtypes:

• Adenocarcinoma — the most common subtype; frequently found in the outer lung regions; most common type in non-smokers and women
• Squamous cell carcinoma — arises from the cells lining the airways; often located centrally near the main bronchi
• Large cell carcinoma — a diverse group of tumours that do not show features of adenocarcinoma or squamous cell type on biopsy

Despite slower growth, 40% of NSCLC patients have disease that has spread beyond the chest at the time of diagnosis.

Small Cell Lung Cancer (SCLC)

Small cell lung cancer accounts for approximately 15% of lung cancers. It is highly aggressive, divides rapidly, and typically has spread to other parts of the body before symptoms appear. SCLC is strongly associated with heavy smoking.

Causes and Risk Factors

• Smoking — responsible for approximately 85% of cases; risk is dose-dependent (pack-years). Former smokers remain at elevated risk for decades after quitting.
• Passive smoke exposure — second-hand smoke raises risk by 20–30%
• Radon gas — a naturally occurring radioactive gas that accumulates in buildings; estimated by the US EPA to be the leading cause among non-smokers and the second leading cause overall in the United States
• Occupational exposures — asbestos, arsenic, chromates, nickel, chloromethyl ethers, polycyclic aromatic hydrocarbons, and coke oven emissions
• Air pollution — particularly fine particulate matter (PM2.5)
• Lung scarring — tuberculosis-related lung damage may predispose to adenocarcinoma
• Genetic factors — a family history of lung cancer confers modest additional risk independent of smoking

Approximately 15–20% of lung cancers occur in people who have never smoked.

Symptoms

Lung cancer often causes no symptoms in its early stages. When symptoms occur, they vary with the tumour's size, location, and pattern of spread.

Pulmonary symptoms:

• Persistent or worsening cough — the most common symptom, especially in smokers whose chronic cough changes character
• Coughing up blood (haemoptysis) — any amount warrants urgent investigation
• Breathlessness or wheezing — from airway obstruction
• Recurrent chest infections or pneumonia that fails to resolve

General symptoms:

• Unintentional weight loss
• Loss of appetite
• Fatigue and weakness
• Chest pain, especially if the tumour invades the chest wall

Symptoms of spread:

• Headache, confusion or seizures — brain metastases
• Bone pain — skeletal metastases
• Jaundice — liver involvement
• Swollen lymph nodes in the neck

Specific syndromes:

• Horner's syndrome — drooping eyelid, small pupil, reduced sweating on one side of the face, caused by tumour compressing neck nerves
• Superior vena cava (SVC) syndrome — swelling of the face, neck and arms from obstruction of the major vein draining the upper body
• Pancoast tumour — shoulder and arm pain from apical tumour pressing on the brachial plexus

Diagnosis

Imaging

Chest X-ray is typically the first investigation, detecting most lung tumours — though small nodules may be missed.

CT scan of the chest provides detailed cross-sectional images, identifying smaller lesions, enlarged lymph nodes, and involvement of surrounding structures. CT guides decisions about which sampling technique to use.

PET-CT scan combines metabolic imaging (PET) with anatomical imaging (CT) to detect active tumour deposits throughout the body. It is the standard for staging — identifying lymph node involvement and distant metastases — and avoids unnecessary surgery in patients with widespread disease.

MRI of the brain is performed to detect cerebral metastases in patients being considered for curative treatment.

Low-dose CT (LDCT) screening can reduce lung cancer mortality in appropriately selected high-risk adults. The original 2011 National Lung Screening Trial (NLST) results reported a 20% relative reduction in lung cancer mortality compared with chest radiography in the trial population; this is not a guaranteed effect for every screening programme. For example, the 2021 US USPSTF recommendation offers annual LDCT to adults aged 50–80 with at least 20 pack-years who currently smoke or quit within the past 15 years. Under that recommendation, screening stops after 15 years without smoking or if a health problem substantially limits life expectancy or the ability or willingness to undergo curative lung surgery. Eligibility, stopping rules and the balance of benefits and harms should be discussed with a clinician using the applicable guideline.

Tissue Diagnosis

A tissue sample (biopsy) is essential to confirm the diagnosis and guide treatment.

• Bronchoscopy — a flexible scope passed through the airway to biopsy accessible tumours; endobronchial ultrasound (EBUS) extends reach to mediastinal lymph nodes
• CT-guided percutaneous needle biopsy — for peripheral tumours not reachable by bronchoscope
• Thoracoscopy (VATS) — minimally invasive surgical sampling for tumours not accessible by other means
• Pleural fluid analysis — if a pleural effusion is present, fluid analysis can confirm malignancy

Molecular and Genetic Testing

Molecular profiling identifies actionable alterations and should be accessible to people with NSCLC. The appropriate panel and timing depend on histology, stage and treatment decisions; broad profiling is especially important in advanced disease, while earlier-stage testing can guide adjuvant or perioperative choices:

Gene/Target	Prevalence in NSCLC	Available Treatment
EGFR mutation	15–30% (higher in Asians)	EGFR inhibitors (osimertinib, gefitinib)
ALK rearrangement	3–5%	ALK inhibitors (alectinib, lorlatinib)
ROS1 rearrangement	1–2%	ROS1 inhibitors (crizotinib, entrectinib)
KRAS G12C	13%	KRAS inhibitors (sotorasib, adagrasib)
BRAF V600E	1–2%	BRAF/MEK inhibitors
PD-L1 expression	Variable	Checkpoint immunotherapy eligibility

Staging

The TNM staging system classifies lung cancer based on:

• T — tumour size and local invasion
• N — lymph node involvement
• M — distant metastasis

Stage	Description	5-Year Survival (NSCLC)
I	Localised to the lung	60–90%
II	Defined by tumour size/local extent and nodal status; can be node-negative	30–60%
III	Locally advanced disease based on tumour extent and/or nodal involvement; can be node-negative	10–35%
IV	Distant metastases	<10% (improving with targeted therapy)

Treatment

Surgery

Surgery offers the best chance of cure in early-stage NSCLC (stages I–II and selected stage III).

• Lobectomy — removal of an entire lobe; the standard curative operation
• Video-assisted thoracoscopic surgery (VATS) — minimally invasive approach with smaller incisions, less pain and faster recovery
• Pneumonectomy — removal of an entire lung; reserved for centrally located tumours
• Sublobar resection (segmentectomy or wedge) — for small peripheral tumours in patients with limited lung reserve

SCLC is rarely treated surgically due to its disseminated nature at diagnosis.

Radiation Therapy

• Stereotactic ablative radiotherapy (SABR/SBRT) — high-dose, precisely targeted radiation for small tumours; an alternative to surgery in patients unfit for operation; cure rates approaching surgery in early-stage disease
• Conventional radiotherapy — combined with chemotherapy (chemoradiation) in locally advanced stage III NSCLC
• Prophylactic cranial irradiation (PCI) — used in SCLC to reduce the risk of brain metastases

Chemotherapy

• When first-line chemotherapy is indicated for NSCLC without an actionable driver, the regimen depends on histology and patient factors; platinum + pemetrexed is an option for nonsquamous disease, while other platinum combinations may include paclitaxel
• First-line chemotherapy for SCLC: cisplatin or carboplatin + etoposide, often combined with immunotherapy
• Chemotherapy is also used as adjuvant therapy after surgery in higher-risk early-stage disease

Targeted Therapy

Targeted therapy can provide substantial benefit for selected molecular alterations. The preferred drug and its benefit relative to chemotherapy depend on the mutation, disease stage and previous treatment; these agents are not interchangeable or universally superior:

• EGFR inhibitors (osimertinib preferred) — median progression-free survival >18 months in EGFR-mutant NSCLC
• ALK inhibitors (alectinib, lorlatinib) — highly effective; may provide years of disease control
• KRAS G12C inhibitors — recently approved; first effective treatment for a previously undruggable target

Immunotherapy

Checkpoint inhibitors help the immune system recognise tumours, but indications differ by drug and regimen:

• In eligible advanced NSCLC, first-line single-agent options include pembrolizumab or atezolizumab under their specific PD-L1 criteria and other eligibility requirements. High PD-L1 alone is insufficient: actionable drivers such as EGFR or ALK can change treatment selection.
• Other NSCLC settings use specific immunotherapy–chemotherapy or dual-immunotherapy regimens; nivolumab alone is not interchangeable with first-line high-PD-L1 monotherapy options.
• In extensive-stage SCLC, established first-line combinations include atezolizumab or durvalumab with platinum–etoposide. Approval and suitability must be checked for the particular regimen and jurisdiction.

Long-term responses to immunotherapy are seen in a subset of patients — some remain in remission for 5+ years.

Lung Cancer Care in China

China's top-tier oncology institutions deliver internationally competitive oncology services:

• Diagnosis pathway: PET-CT, EBUS bronchoscopy, CT-guided biopsy and comprehensive molecular profiling
• Full genomic profiling: next-generation sequencing panels covering all actionable NSCLC targets, including EGFR, ALK, ROS1, KRAS, MET, BRAF, RET and NTRK
• VATS surgery: minimally invasive lobectomy performed routinely; experienced centres achieve excellent outcomes
• SABR: stereotactic radiotherapy available with sub-centimetre targeting precision
• Targeted therapy access: EGFR, ALK, and other targeted agents are available — important for patients requiring long-term maintenance treatment
• Second opinion consultations: rapid multidisciplinary review of imaging and pathology for patients diagnosed elsewhere

Contact a PriumCare care navigator to arrange a lung cancer assessment or treatment consultation.

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External source attribution: the original article cites MSD Manuals, authored by Robert L. Keith MD (University of Colorado School of Medicine), reviewed by Richard K. Albert MD, with a review date of May 2023 and an update in April 2025. These names and dates credit the external source, not authorship or medical review of this PriumCare article.

Additional targeted source clarification

Editorial source check: 25 October 2026. This clarifies the specific claims linked below; it is not a whole-article medical review or a new clinical reviewer attribution. The original publication date is retained.

• WHO: global cancer burden estimates for 2022
• US EPA: radon risk
• NCI: NSCLC staging and regimen-specific treatments
• ASCO: NSCLC biomarker access and treatment selection
• NCI: extensive-stage SCLC treatments
• ASCO: driver-specific treatments and prior-treatment eligibility

Further targeted source clarification

Editorial source check: 25 October 2026. This update checks only the specific residual claims linked below; it is not a whole-article medical review and does not add a named clinical reviewer. The original publication date is retained.

• WHO/IARC: global cancer estimates for 2022

Targeted eligibility and imaging clarification

Editorial source check: 25 October 2026. This update checks only the specific eligibility, histology or imaging statements linked below; it is not a whole-article medical review and adds no named clinical reviewer. The original publication date is retained.

• USPSTF: lung cancer screening eligibility and stopping rules
• NCI: original NLST mortality results and comparator
• FDA: pemetrexed nonsquamous NSCLC indications