Lung cancer remains the leading cause of cancer death in the United States and worldwide, accounting for more deaths than breast, prostate, and colorectal cancers combined. The American Cancer Society (ACS) estimates approximately 234,580 new lung cancer cases will be diagnosed in 2024, resulting in approximately 125,070 deaths—nearly one-quarter of all cancer deaths. However, there is reason for hope: lung cancer death rates have declined 38% from 2005 to 2019 in men and 14% from 2008 to 2019 in women, thanks to decreased smoking rates, earlier detection through screening, and remarkable treatment advances, particularly targeted therapies and immunotherapies that have transformed care for many patients.

Understanding Lung Cancer Types and Biology

Lung cancer develops when cells in the lungs begin growing uncontrollably, forming tumors that can interfere with lung function and spread to other organs. According to the National Cancer Institute (NCI), lung cancers are broadly categorized into two main types based on how cells appear under a microscope, with each type having different growth rates, spread patterns, and treatment approaches.

Non-small cell lung cancer (NSCLC) accounts for approximately 80-85% of all lung cancers. NSCLC grows and spreads more slowly than small cell lung cancer and includes several subtypes. Adenocarcinoma is the most common type, comprising about 40% of lung cancers. It typically develops in the outer regions of the lungs and is the most common lung cancer in non-smokers, women, and younger adults. Adenocarcinomas often grow more slowly than other types and are more likely to be found before spreading. Squamous cell carcinoma accounts for approximately 25-30% of lung cancers and usually develops in the central part of the lungs near the bronchi. This type is strongly associated with smoking. Large cell carcinoma represents about 10% of lung cancers and can appear in any part of the lung. It tends to grow and spread quickly, making it more challenging to treat.

Small cell lung cancer (SCLC) accounts for approximately 10-15% of lung cancers. SCLC grows very rapidly and tends to spread early to other parts of the body. According to the NCI, more than 60% of people with SCLC already have cancer that has spread beyond the lung at diagnosis. SCLC is strongly associated with smoking—it's rare in people who have never smoked. While SCLC initially responds well to chemotherapy and radiation, it often recurs.

The distinction between NSCLC and SCLC is crucial because they're treated differently. NSCLC is often treated with surgery if detected early, followed by chemotherapy, radiation, targeted therapy, or immunotherapy depending on stage and molecular characteristics. SCLC is usually treated with chemotherapy and radiation therapy rather than surgery, as it typically has already spread when diagnosed.

Risk Factors: Smoking and Beyond

Cigarette smoking is the number one risk factor for lung cancer, responsible for approximately 80-90% of lung cancer deaths according to the ACS. The risk increases with the number of cigarettes smoked daily, the number of years smoking, and the age at which smoking began. Smoking damages cells lining the lungs, and over time, this damage can lead to cancer. The NCI reports that current smokers have about 20 times the lung cancer risk of non-smokers. Even smoking a few cigarettes per day or smoking occasionally increases risk significantly.

Former smokers have lower risk than current smokers, with risk decreasing the longer someone has quit. However, lung cancer risk remains elevated even many years after quitting. According to the ACS, approximately 50% of lung cancers in the United States occur in former smokers, highlighting that significant risk persists after smoking cessation. This is why lung cancer screening is recommended for long-term former smokers.

Secondhand smoke exposure increases lung cancer risk in non-smokers by about 20-30% according to the NCI. Approximately 7,300 lung cancer deaths annually in the United States occur in non-smokers due to secondhand smoke exposure. There is no safe level of secondhand smoke exposure—even brief exposures can be harmful.

Radon exposure is the second leading cause of lung cancer after smoking, responsible for approximately 21,000 lung cancer deaths annually in the United States according to the NCI. Radon is a naturally occurring radioactive gas produced by the breakdown of uranium in soil and rocks. It can accumulate in homes, especially in basements and lower levels. The Environmental Protection Agency estimates that about 1 in 15 U.S. homes has elevated radon levels. Testing your home for radon (inexpensive test kits are widely available) and remediating if levels are elevated reduces lung cancer risk.

Occupational exposures to certain substances increase lung cancer risk. According to the ACS, these include asbestos (particularly dangerous when combined with smoking—asbestos-exposed smokers have lung cancer risk 50-90 times higher than non-exposed non-smokers), arsenic, chromium, nickel, beryllium, cadmium, silica, and diesel exhaust. People working in industries with these exposures—including construction, mining, manufacturing, and transportation—face elevated risk. Workplace safety measures including protective equipment and ventilation reduce exposure.

Air pollution contributes to lung cancer risk. The International Agency for Research on Cancer classifies outdoor air pollution as carcinogenic to humans based on lung cancer evidence. The NCI reports that long-term exposure to particulate matter air pollution increases lung cancer risk, though the magnitude of risk is much smaller than smoking.

Additional risk factors include personal or family history of lung cancer, previous radiation therapy to the chest for other cancers (increasing risk 10-15 years later), HIV infection, and certain lung diseases including COPD (chronic obstructive pulmonary disease) and pulmonary fibrosis. Notably, approximately 10-20% of lung cancers occur in people who have never smoked, highlighting that non-smokers can also develop lung cancer.

Lung Cancer Screening: Low-Dose CT for High-Risk Individuals

Because lung cancer is often detected at advanced stages when treatment options are limited and survival rates are low, screening high-risk individuals to detect cancer earlier has been a longstanding goal. The landmark National Lung Screening Trial (NLST), published in 2011, demonstrated that screening high-risk individuals with low-dose computed tomography (LDCT) reduces lung cancer mortality by 20% compared to chest X-rays. This led to current screening recommendations.

The U.S. Preventive Services Task Force (USPSTF) recommends annual lung cancer screening with LDCT for adults ages 50-80 who have a 20 pack-year smoking history and currently smoke or have quit within the past 15 years. Pack-years equal the number of packs smoked per day multiplied by years smoked—for example, smoking one pack daily for 20 years or two packs daily for 10 years both equal 20 pack-years. Screening should be discontinued once a person has not smoked for 15 years, develops a health problem that substantially limits life expectancy, or is unwilling or unable to undergo curative lung surgery if needed.

The American Cancer Society aligns with USPSTF recommendations and emphasizes that screening decisions should occur through shared decision-making discussions between patients and clinicians. According to the ACS, screening should be offered only to people who are in fairly good health and would be candidates for treatment if lung cancer is detected. Screening someone with severe COPD, heart failure, or other conditions that would preclude cancer treatment doesn't benefit them and exposes them to screening harms without potential benefit.

Medicare covers annual lung cancer screening for beneficiaries ages 50-77 who meet the criteria and have no signs or symptoms of lung cancer. A mandatory shared decision-making visit with a healthcare provider must occur before the first screening. During this visit, your provider discusses your lung cancer risk, the benefits and limitations of screening, the importance of maintaining cigarette smoking abstinence if you're a former smoker or achieving abstinence if you still smoke, and the information that will be sought if screening detects abnormalities.

The benefits of lung cancer screening are significant for appropriately selected high-risk individuals. The NCI reports that LDCT screening detected lung cancer at Stage I in 48% of cases in the NLST, compared to only 20% with chest X-rays. Early-stage detection dramatically improves survival—the five-year survival rate for Stage IA non-small cell lung cancer is approximately 90%, compared to only 10% for Stage IV disease.

However, lung cancer screening has important limitations and potential harms that must be understood. False-positive results are common—approximately 24% of screening LDCT scans detect lung nodules or other abnormalities in the NLST. The vast majority of these abnormalities are benign, not cancer. False positives can lead to anxiety, additional imaging, and sometimes invasive procedures including biopsy. Most suspicious findings are monitored with follow-up CT scans rather than immediate biopsy, which minimizes unnecessary invasive procedures while ensuring that true cancers are identified.

Overdiagnosis—detecting slow-growing cancers that would never have caused symptoms or death—occurs in an estimated 18-25% of screen-detected lung cancers. Some lung cancers grow so slowly that they would never have become clinically apparent during a person's lifetime, yet when detected through screening, they're treated with surgery, radiation, or other therapies carrying risks and side effects. Unfortunately, we cannot currently predict which screen-detected cancers would have remained indolent and which will progress, so most detected cancers are treated.

Radiation exposure from repeated annual CT scans is a consideration, though low-dose CT uses significantly less radiation than diagnostic CT (approximately 1.5 mSv per scan, similar to the radiation exposure from living in the United States for six months). The cancer risk from cumulative radiation exposure from screening is estimated to be very small compared to the potential benefit of early cancer detection in high-risk individuals.

Diagnosis, Staging, and Molecular Testing

When lung cancer is suspected—whether due to screening findings, symptoms, or abnormalities on imaging performed for other reasons—several diagnostic procedures may be performed. Imaging tests including chest X-rays, CT scans, PET scans, and brain MRI help characterize suspicious findings and determine whether cancer has spread. Sputum cytology examines mucus coughed up from the lungs under a microscope to look for cancer cells, though this test's sensitivity is limited.

Tissue biopsy is required to definitively diagnose lung cancer. Several biopsy methods exist depending on tumor location. Bronchoscopy involves inserting a thin, flexible tube through the nose or mouth into the airways to visualize tumors and collect tissue samples. Needle biopsy uses a thin needle inserted through the chest wall to sample tumors in outer lung regions, guided by CT imaging. Thoracentesis removes fluid from around the lungs (pleural effusion) to check for cancer cells. Surgical biopsy through video-assisted thoracoscopic surgery (VATS) or open surgery may be needed when less invasive methods aren't feasible or haven't provided a diagnosis.

Once lung cancer is diagnosed, staging determines the extent of disease spread. Lung cancer staging follows the TNM system: T describes tumor size and location, N indicates lymph node involvement, and M shows whether cancer has metastasized to distant sites. NSCLC is staged from I (early, confined to the lung) to IV (advanced, spread to distant sites). SCLC is often simply categorized as limited stage (confined to one side of the chest) or extensive stage (spread more widely). Accurate staging is crucial because it guides treatment decisions and predicts prognosis.

Molecular testing of tumor tissue has become essential for NSCLC treatment planning. According to the NCI, oncologists now routinely test for specific genetic mutations and protein expression that can be targeted by specific therapies. Key molecular markers include EGFR mutations (found in approximately 10-15% of lung adenocarcinomas in the United States, more common in non-smokers and Asian populations), ALK rearrangements (found in approximately 3-5% of NSCLCs, more common in younger patients and non-smokers), ROS1 rearrangements (approximately 1-2% of NSCLCs), BRAF mutations (approximately 2-4% of NSCLCs), and PD-L1 expression (a protein that helps predict response to immunotherapy).

The ACS emphasizes that comprehensive molecular testing should be performed on all advanced NSCLCs (Stage IIIB and IV adenocarcinomas and large cell carcinomas) because targeted therapies for these mutations often provide better outcomes with fewer side effects than traditional chemotherapy.

Treatment Advances: Surgery, Chemotherapy, Targeted Therapy, and Immunotherapy

Lung cancer treatment has advanced dramatically in recent years, particularly for NSCLC. Treatment approach depends on cancer type, stage, molecular characteristics, and patient overall health. Surgery remains the preferred treatment for early-stage NSCLC when possible. Several surgical procedures exist: wedge resection or segmentectomy removes the tumor and a small amount of surrounding lung tissue, lobectomy removes the entire lobe of the lung containing the tumor (the most common surgery for lung cancer), and pneumonectomy removes an entire lung when necessary. Surgery can be performed through traditional open thoracotomy or minimally invasive video-assisted thoracoscopic surgery (VATS) or robotic surgery, which typically result in faster recovery.

According to the NCI, five-year survival rates for patients who undergo complete surgical removal of Stage I NSCLC range from 70-92% depending on tumor size. Surgery is typically not used for SCLC or advanced NSCLC because these cancers have usually spread beyond the lungs.

Radiation therapy uses high-energy beams to kill cancer cells. It's used in several settings: as primary treatment for early-stage lung cancer in patients who cannot tolerate surgery, after surgery to eliminate any remaining cancer cells (adjuvant radiation), before surgery to shrink tumors (neoadjuvant radiation), for advanced cancer to control symptoms and slow growth, and specifically to treat brain metastases. Stereotactic body radiation therapy (SBRT) delivers very precise, high-dose radiation over a few treatments and achieves outcomes similar to surgery for early-stage lung cancer in patients who cannot undergo surgery.

Chemotherapy uses drugs to kill cancer cells throughout the body. It's a mainstay of treatment for both NSCLC and SCLC. For SCLC, chemotherapy (typically platinum-based regimens) combined with radiation is the primary treatment, as SCLC is usually too widespread for surgery. For NSCLC, chemotherapy may be used after surgery to reduce recurrence risk (adjuvant chemotherapy), before surgery to shrink tumors (neoadjuvant chemotherapy), or as primary treatment for advanced disease. Common chemotherapy drugs for lung cancer include cisplatin or carboplatin combined with pemetrexed, paclitaxel, docetaxel, gemcitabine, or vinorelbine.

Targeted therapy has revolutionized treatment for NSCLCs with specific genetic mutations. According to the ACS, targeted therapies attack specific abnormalities in cancer cells, often providing better outcomes with fewer side effects than traditional chemotherapy. EGFR inhibitors including erlotinib, gefitinib, afatinib, and osimertinib treat EGFR-mutated NSCLCs. These oral medications often control cancer for extended periods—osimertinib (Tagrisso) shows progression-free survival averaging 18.9 months as first-line treatment. ALK inhibitors including crizotinib, alectinib, ceritinib, brigatinib, and lorlatinib treat ALK-rearranged NSCLCs with remarkable efficacy. Alectinib achieves median progression-free survival of 34.8 months.

Additional targeted therapies exist for ROS1 rearrangements (crizotinib, entrectinib), BRAF mutations (dabrafenib plus trametinib), NTRK fusions (larotrectinib, entrectinib), MET exon 14 skipping mutations (capmatinib, tepotinib), RET rearrangements (selpercatinib, pralsetinib), and KRAS G12C mutations (sotorasib, adagrasib). The NCI reports that this expanding array of targeted therapies means that comprehensive molecular testing is essential to ensure patients receive the most effective treatment for their specific cancer.

Immunotherapy represents another transformative advance. These treatments harness the immune system to fight cancer. Immune checkpoint inhibitors block proteins (PD-1, PD-L1, CTLA-4) that prevent the immune system from attacking cancer cells. According to the ACS, several immune checkpoint inhibitors are FDA-approved for lung cancer including pembrolizumab (Keytruda), nivolumab (Opdivo), atezolizumab (Tecentriq), durvalumab (Imfinzi), and ipilimumab (Yervoy).

The NCI reports that pembrolizumab used alone as first-line treatment for metastatic NSCLC with high PD-L1 expression (50% or more of tumor cells) achieves median overall survival of 30 months, dramatically better than historical chemotherapy outcomes. Combining immunotherapy with chemotherapy improves outcomes for many patients. Immunotherapy can cause unique side effects called immune-related adverse events when the activated immune system attacks normal tissues, affecting organs including lungs, colon, liver, endocrine glands, and skin. Most immune-related adverse events are manageable with corticosteroids or other immunosuppressive medications.

Prognosis, Survival Rates, and Living with Lung Cancer

Lung cancer survival rates have improved over time but remain lower than many other cancers, primarily because most lung cancers are diagnosed at advanced stages. The ACS reports that the overall five-year relative survival rate for lung cancer is 25%, having increased from 17% in the mid-1990s due to treatment advances and modest increases in early detection. However, survival varies dramatically by stage: five-year relative survival for localized NSCLC is 65%, for regional spread is 37%, and for distant metastases is 8%. For SCLC, five-year survival is 27% for localized disease, 16% for regional disease, and 3% for distant disease.

These statistics represent averages—individual outcomes vary based on many factors including specific cancer type, molecular characteristics, overall health, age, treatment response, and access to cutting-edge therapies. The NCI emphasizes that survival statistics are improving rapidly, particularly for patients whose cancers have targetable mutations or respond to immunotherapy. Some patients with previously fatal metastatic lung cancer now survive for many years with good quality of life.

For lung cancer survivors and those living with the disease, several strategies optimize health and quality of life. Smoking cessation is critical—continuing to smoke after lung cancer diagnosis worsens prognosis, reduces treatment effectiveness, increases treatment side effects, and raises risk of second cancers. Quitting smoking at any point improves outcomes. The ACS recommends that all lung cancer patients who smoke receive intensive smoking cessation counseling and pharmacotherapy.

Pulmonary rehabilitation helps maintain or improve lung function and exercise capacity. Regular physical activity within your abilities improves quality of life, reduces fatigue, and may improve survival. The NCI recommends that lung cancer patients aim for regular moderate exercise as tolerated. Proper nutrition supports treatment tolerance and recovery. Working with a registered dietitian helps address treatment-related eating difficulties, maintain weight, and optimize nutritional status.

Palliative care—specialized medical care focused on relief from symptoms and stress—improves quality of life for people with serious illnesses. Research shows that early integration of palliative care alongside cancer treatment improves quality of life, mood, and even survival in advanced lung cancer. Palliative care addresses pain, shortness of breath, fatigue, and other symptoms while also providing emotional and spiritual support.

Support services including counseling, support groups, and survivorship programs help address anxiety, depression, and fear. Many comprehensive cancer centers offer smoking cessation programs, nutritional counseling, exercise programs, and psychosocial support specifically for lung cancer patients.

While lung cancer remains challenging, remarkable progress in early detection through screening and treatment through targeted therapy and immunotherapy offers unprecedented hope. By understanding risk factors, participating in screening if you're high-risk, seeking prompt evaluation of concerning symptoms, and accessing comprehensive, personalized treatment including molecular testing and targeted therapies when appropriate, outcomes for lung cancer patients continue to improve.