Lung Cancer: Causes, Symptoms, Screening, Stages, and Treatment
Introduction
Lung cancer is one of the most common and serious cancers worldwide. It begins when abnormal cells in the lungs grow uncontrollably, forming tumors that can interfere with breathing and spread to other parts of the body.
This guide explains the causes, symptoms, stages, and treatments for lung cancer, including updates on screening and survival rates.
What Is Lung Cancer?
Lung cancer develops in the tissues of the lungs, most often in the cells lining the air passages. It can spread quickly to nearby lymph nodes or distant organs such as the brain, liver, and bones.
There are two major types of lung cancer, which differ in behavior and treatment approach:
Non-Small Cell Lung Cancer (NSCLC):
Accounts for about 85–90% of cases. Includes subtypes such as adenocarcinoma, squamous cell carcinoma, and large cell carcinoma.
Small Cell Lung Cancer (SCLC):
More aggressive and fast-growing, representing about 10–15% of all lung cancers.
What Causes Lung Cancer?
The leading cause of lung cancer is smoking, which contributes to nearly 85% of cases. However, non-smokers can also develop the disease due to other risk factors.
Key Causes and Risk Factors Include:
Tobacco Smoke Exposure: Cigarettes, cigars, or secondhand smoke.
Radon Gas Exposure: A naturally occurring radioactive gas that can accumulate indoors.
Occupational Exposure: Asbestos, arsenic, diesel exhaust, and other industrial chemicals.
Air Pollution: Long-term exposure to particulate matter increases risk.
Genetic Mutations: Such as KRAS, EGFR, and ALK gene changes that drive abnormal cell growth.
Family History: A family member with lung cancer increases personal risk.
While smoking remains the main risk factor, many lung cancers occur in people who quit years earlier or never smoked.
Early Signs and Symptoms of Lung Cancer
Early stages of lung cancer often have no noticeable symptoms, making screening essential. As the disease progresses, certain warning signs may appear.
Common Symptoms Include:
Persistent cough that worsens over time
Chest pain that deepens with breathing or coughing
Shortness of breath or wheezing
Coughing up blood or rust-colored sputum
Unexplained fatigue or weight loss
Hoarseness or voice changes
Frequent lung infections such as bronchitis or pneumonia
Early Signs in Women:
Women may experience fatigue, back pain, and shoulder pain before typical respiratory symptoms appear, sometimes leading to delayed diagnosis.
How I Knew I Had Lung Cancer – Common Early Clues
Patients often report noticing a lingering cough, shortness of breath during light activity, or chest tightness that persists despite antibiotics or rest.
Because symptoms mimic common respiratory issues, any unexplained cough lasting longer than three weeks warrants medical evaluation.
Lung Cancer Screening
Screening aims to detect lung cancer early — before symptoms appear.
Who Should Be Screened:
According to the U.S. Preventive Services Task Force (USPSTF) and the UK National Screening Committee, screening is recommended for individuals who:
Are between 50–80 years old, and
Have a 20 pack-year smoking history, and
Currently smoke or quit within the past 15 years.
Screening Method:
Low-Dose Computed Tomography (LDCT) is the standard screening tool. It can identify small nodules in the lungs at an early stage, significantly improving survival rates.
National Screening Guidelines:
USPSTF Lung Cancer Screening: Updated in 2021, emphasizes annual LDCT for high-risk individuals.
National Screening Committee (UK): Supports targeted screening pilots using low-dose CT for smokers and ex-smokers.
Lung Cancer X-ray
A chest X-ray is often the first imaging test ordered for respiratory symptoms.
While it can reveal visible masses, small tumors may not appear on X-rays.
If abnormalities are detected, further testing with CT or PET scans is usually required.
Stages of Lung Cancer
Lung cancer staging helps determine the extent of disease and guides treatment planning.
Non-Small Cell Lung Cancer (NSCLC) Stages:
Stage I: Tumor confined to one lung, small in size.
Stage II: Spread to nearby lymph nodes.
Stage III: Spread within the chest to lymph nodes or adjacent structures.
Stage IV: Cancer has metastasized to other organs such as the brain or bones.
Small Cell Lung Cancer (SCLC) Stages:
Limited Stage: Confined to one lung and nearby lymph nodes.
Extensive Stage: Spread to the other lung or distant sites.
Small Cell Lung Cancer (SCLC)
SCLC is characterized by rapid growth and early spread.
It often responds initially to chemotherapy and radiation but tends to relapse.
Symptoms: Persistent cough, chest pain, and fatigue.
Prognosis: Generally poorer than NSCLC due to late detection, though treatment can extend life and relieve symptoms.
Prognosis for SCLC:
Limited Stage: Average 5-year survival rate about 25%.
Extensive Stage: Around 3–7%, depending on response to therapy.
Non-Small Cell Lung Cancer (NSCLC)
NSCLC accounts for most lung cancer cases. It grows and spreads more slowly than SCLC and is often eligible for surgical removal in early stages.
Key Subtypes:
Adenocarcinoma: Common among non-smokers and women.
Squamous Cell Carcinoma: Typically linked to smoking.
Large Cell Carcinoma: Grows and spreads rapidly.
Treatment often involves surgery, targeted therapy, or immunotherapy.
Metastatic Lung Cancer
Metastatic lung cancer occurs when cancer cells spread beyond the lungs to other organs such as the liver, brain, bones, or adrenal glands.
Common signs include bone pain, headaches, or neurological symptoms.
Treatment focuses on slowing disease progression and improving quality of life through systemic therapies.
Lung Cancer Treatment
Treatment varies based on cancer type, stage, and genetic profile.
1. Surgery
Recommended for early-stage NSCLC.
Types include:
Lobectomy: Removal of a lung lobe.
Pneumonectomy: Removal of an entire lung.
Wedge Resection: Removal of a small tumor and surrounding tissue.
2. Chemotherapy
Uses anti-cancer drugs (e.g., cisplatin, carboplatin) to destroy rapidly dividing cells.
Often combined with radiation therapy for better results in both SCLC and advanced NSCLC.
3. Radiation Therapy
High-energy rays target and destroy cancer cells.
Used for localized disease or symptom relief in advanced stages.
4. Targeted Therapy
Drugs that act on genetic mutations such as EGFR, ALK, or KRAS.
These medications block molecular pathways that promote cancer growth.
5. Immunotherapy
Boosts the immune system’s ability to fight cancer cells.
Commonly used drugs include nivolumab and pembrolizumab.
6. New Cancer Treatments
Emerging options include lung cancer vaccines and gene-based therapies, aimed at enhancing immune response and precision targeting of tumor cells.
Chemotherapy for Lung Cancer
Chemotherapy is used:
After surgery (adjuvant) to destroy residual cells.
Before surgery (neoadjuvant) to shrink tumors.
As a primary treatment for inoperable or metastatic cancer.
Side effects vary but can include fatigue, nausea, and temporary immune suppression, which are managed under clinical care.
Lung Cancer Vaccine
Research into therapeutic vaccines aims to stimulate the immune system to recognize lung cancer cells.
While no vaccine currently cures lung cancer, early trials show potential for improved survival when combined with standard therapies.
Lung Cancer ICD-10 Code
The ICD-10 classification for lung cancer is C34, with subcategories depending on tumor site (e.g., C34.1 – Upper lobe, C34.9 – Unspecified site of bronchus or lung).
This code is used for diagnosis and medical record documentation.
Lung Cancer Survival Rate
Survival depends on type, stage, and response to treatment:
Stage I: 5-year survival rate about 60–70%.
Stage II: Around 30–50%.
Stage III: Approximately 15–25%.
Stage IV (Metastatic): Around 5–10%.
Advances in early detection and targeted therapy continue to improve long-term outcomes.
Is Lung Cancer Curable?
Yes — when detected early and localized, lung cancer can be treated effectively or cured through surgery and modern therapies.
In advanced stages, treatment focuses on extending survival, controlling symptoms, and maintaining quality of life.
Key Takeaways
Lung cancer is often preventable and treatable when caught early.
Smoking cessation is the most effective prevention measure.
Annual low-dose CT screening saves lives in high-risk groups.
Both SCLC and NSCLC require personalized treatment strategies.
Ongoing research into targeted and immune therapies is improving outcomes globally.
Disclaimer
This article is for educational and informational purposes only. It does not provide medical advice or substitute professional healthcare consultation.
Individuals experiencing respiratory symptoms or with risk factors should consult a qualified physician or oncologist for proper evaluation.