Lung Cancer

Overview
Epidemiology
NSCLC vs SCLC Classification
Molecular Profiling and Targeted Mutations
Clinical Presentation and Staging
Diagnosis and Screening
Treatment — Targeted Therapy and Immunotherapy
Chemotherapy and Radiation
Prognosis and Survival
Prevention
Research Papers
PubMed Searches
Connections

Overview

Lung cancer is the leading cause of cancer death worldwide, accounting for more deaths each year than breast, colon, and prostate cancers combined. Despite advances in early detection and treatment, it carries a heavy mortality burden because most cases are diagnosed at advanced stages when curative surgery is no longer possible. Understanding the two broad categories — non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC) — is essential, because they behave differently, respond to different treatments, and carry very different prognoses.

NSCLC accounts for approximately 85% of all lung cancers and is further divided into three main histological subtypes. Adenocarcinoma, the most common subtype at roughly 40% of all cases, arises from glandular cells lining the small airways, tends to occur in peripheral lung tissue, and is disproportionately represented among non-smokers and women. Squamous cell carcinoma comprises about 30% of cases, originates in the central airways near the bronchi, and is strongly associated with tobacco smoking. Large cell carcinoma, a poorly differentiated catch-all category, accounts for roughly 10–15% of NSCLC cases and is diagnosed by exclusion after ruling out the more specific subtypes.

SCLC constitutes the remaining 15% of lung cancers. It is a neuroendocrine tumor of extraordinary aggressiveness — it grows and spreads faster than any other lung cancer subtype. SCLC is almost exclusively seen in heavy smokers and has typically metastasized to distant sites by the time symptoms appear. While it responds dramatically to initial platinum-based chemotherapy, relapse is nearly universal, and long-term survival rates remain poor. Its neuroendocrine origin produces a distinctive set of paraneoplastic syndromes not typically seen in NSCLC.

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Epidemiology

Lung cancer is a major public health burden in the United States and globally. Each year, approximately 238,000 new cases are diagnosed in the US, with about 127,000 deaths — numbers that make it the top cancer killer by a wide margin. Worldwide, the figures are even more stark: over 2.2 million new cases and 1.8 million deaths annually, according to GLOBOCAN data.

Tobacco smoking is by far the dominant risk factor, responsible for approximately 85% of all lung cancer cases. The risk increases with both the intensity of smoking (pack-years) and the duration, though the relationship is not perfectly linear. Former smokers retain elevated risk for decades after quitting, though cessation substantially reduces that risk over time. The widespread adoption of filtered cigarettes during the mid-20th century changed the landscape of lung cancer histology: filters trap large particles but allow smaller ones to penetrate deeper into the peripheral airways, which is believed to partly explain why adenocarcinoma has supplanted squamous cell carcinoma as the most common subtype in many countries.

Non-smokers are not immune. About 10–15% of lung cancers in the US occur in never-smokers, and among these patients, adenocarcinoma — particularly with driver mutations in EGFR or ALK — is strongly overrepresented. Exposure to secondhand smoke, radon gas (a natural radioactive gas that seeps into buildings from soil), asbestos, and other occupational carcinogens (nickel, chromium, arsenic, diesel exhaust) all contribute to risk in non-smokers. Air pollution, particularly fine particulate matter (PM2.5), is an emerging risk factor supported by epidemiological data in never-smokers globally.

The median age at diagnosis is approximately 70 years, and lung cancer remains uncommon before age 40. The overall 5-year survival rate has improved from around 15% a decade ago to approximately 22% today, largely driven by the introduction of targeted therapies and immune checkpoint inhibitors for advanced disease. However, survival varies enormously by stage: patients diagnosed at stage I have 5-year survival rates exceeding 70%, while those diagnosed at stage IV historically had rates below 5%, now somewhat improved with modern systemic therapies.

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NSCLC vs SCLC Classification

The distinction between NSCLC and SCLC drives nearly every treatment decision in lung oncology, so accurate histological classification — supported by immunohistochemistry and, increasingly, molecular profiling — is the essential first step after diagnosis.

Non-Small Cell Lung Cancer (NSCLC)

NSCLC is staged using the TNM (tumor, nodes, metastasis) system maintained by the American Joint Committee on Cancer (AJCC) and the International Association for the Study of Lung Cancer (IASLC). The T descriptor captures tumor size and local invasion; N describes involvement of regional lymph nodes (hilar, mediastinal, supraclavicular); M records distant metastasis. The combined TNM descriptors yield pathological stages I through IV, which govern both prognosis and treatment intent — curative surgery for resectable early-stage disease, concurrent chemoradiation for unresectable stage III, and systemic therapy for stage IV.

Adenocarcinoma: Peripheral location, slower growth rate (doubling time 100–400 days), frequent EGFR/ALK/ROS1 driver mutations, more common in non-smokers and women. Lepidic growth pattern (formerly bronchoalveolar carcinoma) carries the best prognosis within this subtype.
Squamous cell carcinoma: Central hilar location, arises from bronchial epithelium, associated with cavitation on imaging, hypercalcemia via PTHrP secretion. FGFR1 amplification and KEAP1 mutations are common; EGFR mutations are rare. Responds less predictably to pemetrexed-based regimens.
Large cell carcinoma: Poorly differentiated, diagnosed by exclusion. Lacks the glandular features of adenocarcinoma and the squamoid features of SCC. Tends to present as large peripheral masses. Some cases reclassified as adenocarcinoma or SCC with deeper IHC staining.

Small Cell Lung Cancer (SCLC)

SCLC uses a simplified two-stage system. Limited-stage disease is confined to one hemithorax and can be encompassed within a single radiation field (roughly corresponding to stage I–IIIB of the NSCLC TNM). Extensive-stage disease has spread beyond the hemithorax, including contralateral lung or distant organs — this is present in about 60–70% of patients at diagnosis.

SCLC has a doubling time of approximately 25–30 days — several times faster than most NSCLC subtypes. It spreads hematogenously early and preferentially seeds the brain, bone, liver, and adrenal glands. The initial response rate to platinum-based chemotherapy is high (60–80%), but most patients relapse within 6–12 months, and second-line therapy produces modest responses. Paraneoplastic syndromes are a defining feature: syndrome of inappropriate antidiuretic hormone (SIADH) leading to hyponatremia, Lambert-Eaton myasthenic syndrome (VGCC antibodies producing proximal weakness and areflexia), ectopic ACTH production causing Cushing's syndrome, and anti-Hu antibody encephalomyelitis are all characteristic.

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Molecular Profiling and Targeted Mutations

The discovery that a subset of NSCLC tumors are driven by single oncogenic mutations — so-called "driver mutations" — transformed lung cancer treatment over the past two decades. Modern targeted therapies that specifically inhibit the mutant kinase produce response rates, progression-free survival, and quality-of-life outcomes that far exceed those of cytotoxic chemotherapy in biomarker-selected patients. Comprehensive next-generation sequencing (NGS) of tumor tissue is now standard of care for all patients with advanced NSCLC, with liquid biopsy of circulating tumor DNA (ctDNA) as a complementary or alternative approach when tissue is insufficient.

EGFR Mutations

Mutations in exon 19 (in-frame deletions) and exon 21 (L858R point mutation) account for the vast majority of EGFR-activating mutations and predict sensitivity to EGFR tyrosine kinase inhibitors (TKIs). These mutations occur in 10–15% of NSCLC patients in Western populations and 40–50% of patients in East Asian populations, particularly non-smoking women with adenocarcinoma. First-generation TKIs (erlotinib, gefitinib) and second-generation agents (afatinib, dacomitinib) were the standard until osimertinib, a third-generation EGFR TKI that penetrates the blood-brain barrier and overcomes the T790M resistance mutation, demonstrated superior progression-free survival in the FLAURA trial and is now the preferred first-line agent. Osimertinib also received approval in the adjuvant setting for resected stage IB–IIIA EGFR-mutant NSCLC after the ADAURA trial showed dramatic improvement in disease-free survival.

ALK Rearrangements

Chromosomal rearrangements fusing ALK with partner genes (most commonly EML4) occur in 3–5% of NSCLC patients and define a biologically distinct subset: typically younger, never- or light-smokers with adenocarcinoma. Crizotinib was the first approved ALK inhibitor, followed by second-generation agents ceritinib and alectinib, and third-generation lorlatinib. Alectinib demonstrated superior progression-free survival (34.8 vs 10.9 months) compared to crizotinib in the ALEX trial and is the preferred first-line choice for ALK-positive NSCLC.

KRAS G12C

KRAS mutations are the most common oncogenic driver in NSCLC (~25% of all cases), but most KRAS variants were considered undruggable for decades. The specific G12C substitution (~13% of NSCLC) creates a reactive cysteine that can be covalently targeted. Sotorasib (AMG 510) was approved in 2021 based on a 37.1% objective response rate in pre-treated KRAS G12C NSCLC. Adagrasib is an alternative approved agent with CNS penetration. Combination strategies with SHP2 inhibitors and immunotherapy are under active investigation.

ROS1 Rearrangements

ROS1 fusions occur in approximately 1–2% of NSCLC, again in younger non-smokers with adenocarcinoma. ROS1 shares structural homology with ALK, and crizotinib — the first approved ALK inhibitor — also effectively inhibits ROS1. Entrectinib, with CNS activity, is an alternative first-line option.

BRAF V600E

BRAF V600E mutations occur in approximately 2–4% of NSCLC adenocarcinomas. The combination of dabrafenib (BRAF inhibitor) plus trametinib (MEK inhibitor), validated in melanoma, also produces high response rates in BRAF V600E-mutant NSCLC and is the approved regimen.

MET Exon 14 Skipping

MET exon 14 skipping mutations occur in 3–4% of NSCLC and more frequently in elderly patients with sarcomatoid carcinoma or pleomorphic histology. Capmatinib and tepotinib are approved MET inhibitors with substantial response rates (40–70%) in this biomarker-selected population.

NTRK Fusions

NTRK1/2/3 fusions are rare (<1%) but occur across multiple tumor types. Larotrectinib and entrectinib are histology-agnostic TRK inhibitors approved for NTRK fusion-positive cancers regardless of site of origin.

PD-L1 Expression and Immunotherapy Biomarkers

Programmed death-ligand 1 (PD-L1) expression on tumor cells, quantified as tumor proportion score (TPS), predicts response to immune checkpoint inhibitors. TPS ≥50% identifies patients most likely to benefit from pembrolizumab monotherapy as first-line therapy (KEYNOTE-024). For TPS 1–49%, pembrolizumab is combined with platinum-based chemotherapy. Tumor mutational burden (TMB-high, defined as ≥10 mutations per megabase) is an FDA-approved biomarker for pembrolizumab in solid tumors. STK11 co-mutations in KRAS-mutant NSCLC are associated with poor immunotherapy response.

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Clinical Presentation and Staging

Most lung cancers are asymptomatic in early stages — the lung has limited sensory innervation, and tumors can reach considerable size before producing symptoms. The classic triad of new or worsened cough, hemoptysis, and unexplained weight loss should prompt urgent evaluation, though any individual symptom may be the sole presenting complaint. Dyspnea, chest pain (particularly pleuritic), hoarseness (left recurrent laryngeal nerve compression), and fatigue are also common.

Central vs Peripheral Tumor Presentations

Central tumors (squamous cell carcinoma, SCLC) arise in the main or lobar bronchi and tend to produce endobronchial symptoms: post-obstructive pneumonia, lobar atelectasis, and wheezing that does not resolve with bronchodilators. Peripheral tumors (adenocarcinoma) grow silently until they invade the pleura, producing pleuritic pain or malignant pleural effusion, or until they are large enough to cause compressive symptoms.

Specific Syndromes

Superior vena cava (SVC) syndrome: Obstruction of the SVC by mediastinal adenopathy or direct tumor invasion causes facial plethora, arm edema, engorged neck veins, and headache — an oncological urgency requiring prompt radiotherapy or systemic treatment.
Pancoast tumor (superior sulcus tumor): Apical lung tumors that invade the chest wall, brachial plexus, and sympathetic chain produce Horner's syndrome (ptosis, miosis, anhidrosis) plus ipsilateral shoulder and arm pain radiating in a C8-T1 distribution. Treatment involves concurrent chemoradiation followed by surgical resection when feasible.
Paraneoplastic syndromes — NSCLC: Hypercalcemia mediated by PTHrP is characteristic of squamous cell carcinoma. Hypertrophic pulmonary osteoarthropathy (periosteal new bone formation with painful wrists and ankles) occurs in adenocarcinoma.
Paraneoplastic syndromes — SCLC: SIADH (hyponatremia), Lambert-Eaton myasthenic syndrome (voltage-gated calcium channel antibodies, proximal weakness, reduced reflexes — improves with exercise, unlike myasthenia gravis), ectopic ACTH (Cushing's syndrome with hypokalemia and metabolic alkalosis), and anti-Hu antibody limbic encephalitis.

Staging

The 8th edition IASLC/AJCC TNM staging system classifies NSCLC into stages I through IV based on T (tumor size/invasion), N (nodal involvement: N0 = none, N1 = ipsilateral hilar, N2 = ipsilateral mediastinal/subcarinal, N3 = contralateral mediastinal or supraclavicular), and M (M0 = no distant metastasis, M1a = contralateral lung/malignant effusion, M1b = single extrathoracic metastasis, M1c = multiple extrathoracic metastases). The most common sites of distant metastasis for NSCLC are the brain, bone, liver, and adrenal glands — each with specific management implications (e.g., stereotactic radiosurgery for limited brain metastases, bisphosphonates/denosumab for bone metastases).

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Diagnosis and Screening

Tissue Diagnosis

Histological confirmation is mandatory before initiating treatment. The approach depends on tumor location and accessibility. CT-guided percutaneous needle biopsy is the workhorse for peripheral lesions, achieving diagnostic accuracy exceeding 90% in experienced centers. Bronchoscopy with endobronchial biopsy is used for central lesions visible to the bronchoscope. Endobronchial ultrasound-guided transbronchial needle aspiration (EBUS-TBNA) has revolutionized mediastinal staging, allowing real-time sampling of paratracheal, subcarinal, and hilar lymph nodes without mediastinoscopy. Video-assisted thoracoscopic surgery (VATS) is reserved for lesions inaccessible by less invasive means and provides larger tissue samples for molecular profiling.

Staging Workup

Integrated PET-CT scanning is the standard for initial staging of NSCLC. It detects hypermetabolic mediastinal nodes and distant metastases with sensitivity and specificity superior to CT alone, and frequently upstages or downstages disease compared to CT. Brain MRI is mandatory in all patients with stage III–IV NSCLC (brain metastases are present at diagnosis in 10–25% of stage IV patients) and in all SCLC patients. Bone scan has largely been replaced by PET-CT, which images the skeleton simultaneously. Pulmonary function testing is essential before surgical resection to assess predicted postoperative FEV1 and DLCO.

Molecular Testing

All patients with metastatic non-squamous NSCLC should have comprehensive molecular profiling at diagnosis. Minimum testing includes EGFR, ALK, ROS1, BRAF V600E, MET exon 14, KRAS G12C, NTRK fusions, RET fusions, and PD-L1 TPS. NGS-based panels that cover all actionable alterations simultaneously are preferred over sequential single-gene testing, which delays treatment. When tumor tissue is insufficient, liquid biopsy (plasma ctDNA) captures approximately 50–80% of driver mutations detectable in tissue and enables faster turnaround. Liquid biopsy is also the standard method for detecting resistance mutations (e.g., EGFR T790M, C797S) at progression on targeted therapy.

Low-Dose CT Lung Cancer Screening

The National Lung Screening Trial (NLST) demonstrated that annual low-dose CT (LDCT) screening reduced lung cancer mortality by approximately 20% compared to chest X-ray in high-risk individuals. The USPSTF updated its screening criteria in 2021: annual LDCT is recommended for adults aged 50–80 years who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years. Shared decision-making regarding the benefits (early detection, mortality reduction), harms (false positives, unnecessary procedures, radiation exposure, psychological distress), and logistics is integral to the screening process. Lung-RADS, the standardized reporting system developed by the American College of Radiology, categorizes nodule findings to guide management decisions.

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Treatment — Targeted Therapy and Immunotherapy

EGFR-Targeted Therapy

Osimertinib is the preferred first-line treatment for metastatic EGFR-mutant (exon 19 del or L858R) NSCLC, based on the FLAURA trial showing superior progression-free survival (18.9 vs 10.2 months) and overall survival (38.6 vs 31.8 months) compared to erlotinib or gefitinib. Its CNS penetration makes it particularly valuable for patients with brain metastases, which are present at diagnosis in 20–40% of EGFR-mutant NSCLC. In the adjuvant setting, the ADAURA trial showed osimertinib after resection of stage IB–IIIA EGFR-mutant NSCLC reduced the risk of disease recurrence or death by 83% at 3 years compared to placebo, leading to its approval in this curative-intent setting.

ALK-Targeted Therapy

Alectinib is the preferred first-line agent for ALK-positive metastatic NSCLC. The ALEX trial demonstrated progression-free survival of 34.8 months with alectinib versus 10.9 months with crizotinib. Alectinib also has excellent CNS penetration, reducing the rate of CNS progression compared to crizotinib. Lorlatinib, a third-generation ALK inhibitor effective against most known ALK resistance mutations, is used after disease progression on alectinib or brigatinib.

Immunotherapy

Pembrolizumab, an anti-PD-1 monoclonal antibody, has transformed first-line treatment of advanced NSCLC without driver mutations. KEYNOTE-024 established pembrolizumab monotherapy as the standard of care for PD-L1 TPS ≥50% NSCLC, with superior overall survival compared to platinum-based chemotherapy (HR 0.63). For PD-L1 TPS 1–49%, or TPS <1% with excellent performance status, pembrolizumab combined with platinum-based chemotherapy (carboplatin/pemetrexed for non-squamous; carboplatin/paclitaxel for squamous) is the standard first-line approach. Atezolizumab (anti-PD-L1) and nivolumab (anti-PD-1) are approved in the second-line setting and in combination regimens for specific indications.

Durvalumab, an anti-PD-L1 antibody, received approval for unresectable stage III NSCLC after concurrent chemoradiation based on the PACIFIC trial, which demonstrated significant improvement in progression-free survival (16.8 vs 5.6 months) and overall survival. The neoadjuvant approach was validated by CheckMate 816, which showed that nivolumab combined with platinum-based chemotherapy before surgery for resectable NSCLC (stage IB–IIIA) achieved a pathological complete response rate of 24% versus 2.2% with chemotherapy alone, with improvement in event-free survival.

Immune-Related Adverse Events (irAEs)

Checkpoint inhibitors unleash T-cell activity against tumors but can simultaneously trigger autoimmune inflammation in virtually any organ. Common irAEs include immune-mediated pneumonitis (dyspnea, cough, ground-glass opacities on CT — potentially fatal if severe), colitis (diarrhea), hepatitis (transaminase elevation), thyroiditis (hypo- or hyperthyroidism), skin toxicities (rash, pruritus), and hypophysitis. Management involves withholding immunotherapy, administering systemic corticosteroids (prednisone 1–2 mg/kg/day for grade 2–3), and escalating to steroid-sparing immunosuppression (infliximab for colitis, mycophenolate for hepatitis) if corticosteroids are insufficient. Grade 3–4 irAEs generally require permanent discontinuation of immunotherapy.

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Chemotherapy and Radiation

First-Line Chemotherapy Regimens

Platinum-based doublet chemotherapy remains the backbone of treatment for patients without actionable driver mutations and low PD-L1 expression, and is combined with immunotherapy in the first-line setting. Carboplatin plus paclitaxel (or nab-paclitaxel) is the most commonly used doublet in the US for squamous NSCLC. Cisplatin or carboplatin combined with pemetrexed is preferred for non-squamous (adenocarcinoma) histology, as pemetrexed is ineffective in squamous cell carcinoma due to high thymidylate synthase expression. Bevacizumab, an anti-VEGF antibody, can be added to carboplatin/paclitaxel in non-squamous NSCLC with appropriate patient selection (excluding patients with squamous histology, hemoptysis, or anticoagulation requirements).

SCLC Chemotherapy

Etoposide plus platinum (carboplatin or cisplatin) remains the foundational regimen for both limited- and extensive-stage SCLC. For extensive-stage disease, atezolizumab added to carboplatin/etoposide (IMpower133 trial) or durvalumab added to etoposide/platinum (CASPIAN trial) demonstrated modest but statistically significant improvements in overall survival and are approved first-line regimens. Second-line SCLC options include topotecan (the only FDA-approved agent in this setting), lurbinectedin (approved based on response rate data), and clinical trial enrollment.

Radiation Therapy

Stereotactic body radiation therapy (SBRT), also called stereotactic ablative radiotherapy (SABR), delivers high doses of precisely targeted radiation in 3–5 fractions and is the standard treatment for early-stage (stage I–II) NSCLC in patients who are medically inoperable. Local control rates exceed 90% at 3 years with SBRT — comparable to surgical outcomes in selected cases — while sparing surrounding normal lung tissue.

For unresectable stage III NSCLC, concurrent chemoradiation (cisplatin/etoposide or carboplatin/paclitaxel concurrently with thoracic radiotherapy to 60–66 Gy) is the standard of care, followed by consolidation durvalumab for patients without disease progression. Sequential chemoradiation (chemo first, then radiation) produces lower response rates and worse survival than concurrent treatment but may be used in patients unable to tolerate the toxicity of concurrent therapy.

Prophylactic cranial irradiation (PCI) reduces the rate of brain metastasis and improves survival in limited-stage SCLC patients who achieve complete or near-complete response to initial chemoradiation. Its role in extensive-stage SCLC is more controversial, particularly given data suggesting that close surveillance MRI with salvage treatment may be an equivalent alternative that spares the neurocognitive toxicity of prophylactic irradiation.

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Prognosis and Survival

Prognosis in lung cancer varies enormously by stage, histology, and the presence of actionable biomarkers. Stage at diagnosis remains the single most powerful determinant of outcome, which is why efforts to expand LDCT screening to high-risk populations are so important — stage I disease is curable in the majority of patients with surgery alone.

NSCLC 5-Year Survival by Stage (SEER data)

Stage IA1: ~92%
Stage IA2: ~83%
Stage IA3: ~77%
Stage IB: ~68%
Stage IIA: ~60%
Stage IIB: ~53%
Stage IIIA: ~36%
Stage IIIB: ~19%
Stage IVA: ~10%
Stage IVB: ~0–3%

Impact of Targeted Therapies

Targeted therapies have dramatically altered the prognosis of biomarker-selected patients with advanced NSCLC. Patients with EGFR-mutant NSCLC treated with osimertinib have a median progression-free survival of approximately 18–19 months in the first-line setting, compared to 8–10 months with first-generation TKIs and approximately 4–6 months with platinum doublet chemotherapy. Overall survival in EGFR-mutant patients has now exceeded 3 years in landmark trials. ALK-positive patients treated with alectinib have median progression-free survival approaching 3 years, an outcome that would have been unthinkable with chemotherapy. Some patients with EGFR or ALK driver mutations and limited-volume metastatic disease achieve prolonged disease control measured in years.

SCLC Prognosis

SCLC carries a substantially worse prognosis than NSCLC at comparable clinical stages. In limited-stage disease, treated with concurrent chemoradiation and consolidation immunotherapy, the median survival is approximately 15–20 months and 5-year survival is around 15–25%. Extensive-stage disease has a median survival of approximately 10–12 months with contemporary chemoimmunotherapy regimens; fewer than 5% of extensive-stage patients survive 5 years. The development of durable responses with checkpoint inhibitors has improved survival at the tail of the curve but has not produced the transformative outcomes seen with targeted therapies in driver-mutant NSCLC.

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Prevention

The most impactful single intervention to prevent lung cancer is smoking cessation. The risk of lung cancer declines significantly within years of quitting, and after 15–20 years of abstinence, former heavy smokers approach the risk of never-smokers, though it does not return fully to baseline. Every clinical encounter is an opportunity to offer smoking cessation counseling and pharmacotherapy: nicotine replacement therapy (patch, gum, lozenge, inhaler), bupropion, and varenicline (the most effective agent, producing 12-month abstinence rates approximately twice those of placebo) are all evidence-based. Combination pharmacotherapy (e.g., nicotine patch plus short-acting nicotine) plus behavioral support produces higher cessation rates than either alone.

Radon is the second leading cause of lung cancer in the US, responsible for approximately 21,000 deaths annually. It is a colorless, odorless, naturally occurring radioactive gas produced by uranium decay in soil and rock that enters buildings through foundation cracks. The EPA recommends testing all homes for radon and installing sub-slab depressurization systems in any home with radon levels at or above 4 pCi/L. Testing kits are inexpensive and widely available.

Occupational carcinogen exposures account for a meaningful fraction of lung cancer cases. Asbestos (particularly chrysotile and amphibole fibers, which cause both lung cancer and mesothelioma), crystalline silica, nickel compounds, chromium VI, beryllium, arsenic, and diesel exhaust are all established lung carcinogens. Engineering controls, appropriate respiratory protective equipment, and regulatory limits on workplace exposure concentrations reduce occupational risk. Former asbestos workers who smoke face a multiplicative (not merely additive) increase in lung cancer risk — smoking cessation in this population is especially urgent.

LDCT screening per USPSTF guidelines is itself a preventive intervention in the sense that it shifts diagnosis from advanced to early stages, where curative treatment is possible. Population-level uptake of LDCT screening in the US remains below 20% among eligible individuals — a significant missed opportunity for mortality reduction. Expansion of shared decision-making conversations in primary care settings and improved access to accredited lung cancer screening programs are public health priorities.

A Mediterranean-style diet rich in fruits, vegetables, and whole grains is associated with modestly reduced lung cancer risk in observational studies, likely due to antioxidant micronutrients. However, high-dose supplementation with beta-carotene substantially increased lung cancer risk in heavy smokers in the CARET and ATBC trials — demonstrating that dietary antioxidants cannot be simply translated into supplement form and that supplementation in high-risk groups requires careful evidence review.

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