Lung Cancer: A Complete Guide to Understanding, Diagnosing, and treatment

Lung cancer is one of those diagnoses that can stop time. It’s not just a medical condition—it’s a life-altering event. Whether you’ve just heard the words from a doctor, or you’re researching for someone you love, understanding lung cancer in a clear, human way can make all the difference. In this comprehensive guide, we’ll walk through everything—from what it really is, why it happens, to how it’s treated today.

What is Lung Cancer?

Lung cancer is a disease where abnormal cells grow uncontrollably in the lungs, often forming tumors that interfere with normal lung function. These cells can also spread (metastasise) to other parts of the body if not caught early.

It’s the leading cause of cancer deaths globally. According to the World Health Organization, lung cancer accounted for nearly 1.8 million deaths in 2020 alone. There are two main types:

• Non-small cell lung cancer (NSCLC) – accounts for about 85% of cases.
• Small cell lung cancer (SCLC) – tends to spread faster and is usually linked to heavy smoking.

The disease can affect anyone, but it most often develops in people aged 65 or older.

How Does Lung Cancer Occur?

Think of your lungs like a sponge—soft, delicate, and filled with tiny airways. Now imagine if one cell in that sponge goes rogue, dividing when it shouldn’t. That’s essentially how lung cancer begins.

Lung cancer starts when DNA in lung cells becomes damaged—usually from repeated exposure to toxins like cigarette smoke. This DNA damage means the cell doesn’t “know” when to stop growing. Over time, the cell divides uncontrollably and forms a tumour. If left unchecked, these rogue cells can travel to other organs—much like an aggressive weed invading an entire garden.

What Are the Causes of Lung Cancer?

Lung cancer doesn’t just pop up out of nowhere. It’s usually the result of long-term exposure to harmful substances. The biggest culprit? Cigarette smoking.

Here’s a breakdown of common causes:

• Smoking (Active): About 85% of lung cancers are related to tobacco smoking. Cigarettes contain over 70 known carcinogens.
• Second-hand smoke: Even if you don’t smoke, breathing in smoke from others can raise your risk.
• Radon gas: This naturally occurring radioactive gas is the second leading cause of lung cancer, especially in non-smokers.
• Occupational exposure: Jobs that expose workers to asbestos, diesel exhaust, arsenic, or chromium can increase risk.
• Air pollution: Long-term exposure to polluted air, especially in cities, contributes to the risk.
• Genetics: A family history of lung cancer may also increase susceptibility.

Risk Factors

Not everyone exposed to these causes will develop lung cancer. But some factors significantly raise your risk.

Here are the key risk factors:

• Smoking (biggest risk factor)
• Age over 65
• Family history of lung cancer
• Previous radiation therapy to the chest
• Living in a home with high radon levels
• Chronic lung diseases like COPD or pulmonary fibrosis
• Occupational exposure to cancer-causing agents
• Weakened immune system

The more risk factors you have, the higher the chance—but having none doesn’t mean you’re completely safe either.

Symptoms of Lung Cancer

What makes lung cancer tricky is that early on, it may not cause any symptoms. But as the disease progresses, signs start to show up.

Common symptoms include:

• Persistent cough that doesn’t go away or worsens
• Coughing up blood
• Shortness of breath
• Chest pain, especially with deep breathing or coughing
• Wheezing
• Hoarseness
• Unexplained weight loss
• Fatigue or weakness
• Recurrent infections like bronchitis or pneumonia

Why do these symptoms happen? Well, tumors in the lungs can block airways, irritate nerves, or invade surrounding tissues—causing pain, breathing difficulties, and more.

Differential Diagnosis: What Else Could It Be?

Before jumping to conclusions, doctors need to rule out other conditions that can mimic lung cancer symptoms. That’s what a “differential diagnosis” means.

Here are some possibilities:

• Tuberculosis (TB): Chronic cough and weight loss may resemble lung cancer.
• Chronic bronchitis: Often seen in smokers, causing persistent cough and mucus.
• Pneumonia: Causes cough, fever, and lung infiltrates that may look like cancer on X-rays.
• COPD (Chronic Obstructive Pulmonary Disease): Breathing difficulty and wheezing.
• Pulmonary embolism: Sudden chest pain and shortness of breath.
• Lung abscess or fungal infections: Can also form lung masses on imaging.

That’s why detailed testing is essential before confirming a cancer diagnosis.

How Is Lung Cancer Diagnosed?

So how do doctors figure out if it’s lung cancer? Let’s break it down.

1. Imaging Tests

• Chest X-ray: Often the first step, but may miss small tumors.
• CT scan: Offers a more detailed picture of lung masses and lymph nodes.
• PET scan: Checks if cancer has spread by tracking metabolic activity.

2. Biopsy (Gold Standard)

The gold standard for diagnosing lung cancer is a tissue biopsy. This involves removing a sample of suspicious tissue and examining it under a microscope.

Types of biopsy include:

• Bronchoscopy: A thin tube goes down the throat into the lungs to collect cells.
• CT-guided needle biopsy: For tumors in outer parts of the lung.
• Surgical biopsy: Done if other methods fail to give a clear diagnosis.

3. Lab Tests

• Molecular testing: Looks for mutations like EGFR, ALK, KRAS which may guide targeted therapy.
• Blood tests: May be done to assess overall health or check tumor markers, although not diagnostic on their own.

Stages of Lung Cancer

Knowing the stage helps doctors choose the best treatment plan.

NSCLC is staged from I to IV:

• Stage I: Tumor is small and confined to the lung
• Stage II: Cancer has spread to nearby lymph nodes
• Stage III: Cancer has spread more widely within the chest
• Stage IV: Cancer has spread to other parts of the body (metastatic)

SCLC is staged as:

• Limited stage: Confined to one lung and nearby lymph nodes
• Extensive stage: Spread beyond that area

Treatment of Lung Cancer

Once diagnosed, what’s next?

Treatment depends on the type, stage, and patient’s overall health. Here’s what’s commonly used:

1. Surgery (Best for Early Stage)

• Lobectomy: Removing a lobe of the lung
• Pneumonectomy: Removing an entire lung
• Segmentectomy: Removing part of a lobe

Surgery is most effective when the cancer hasn’t spread beyond the lungs.

2. Radiation Therapy

High-energy beams are used to destroy cancer cells. It can be used:

• As a main treatment (especially in patients who can’t have surgery)
• After surgery to kill remaining cancer cells
• For symptom relief in advanced cancer

3. Chemotherapy

Drugs like cisplatin, carboplatin, etoposide, and pemetrexed are used to kill fast-growing cells. Often used for both NSCLC and SCLC.

4. Targeted Therapy

If genetic mutations are found, targeted therapy can block them:

• EGFR mutation – treated with osimertinib
• ALK rearrangement – treated with alectinib
• KRAS G12C – treated with sotorasib

5. Immunotherapy

Medicines like nivolumab or pembrolizumab help the body’s immune system fight cancer. Often used in advanced stages.

6. Palliative Care

When a cure isn’t possible, palliative treatments can improve quality of life—relieving symptoms like pain or shortness of breath.

Can Lung Cancer Be Prevented?

While not all cases are preventable, many are.

Here’s how to lower your risk:

• Don’t smoke, and quit if you do.
• Avoid second-hand smoke
• Test your home for radon
• Use protective gear if you work around carcinogens
• Eat a balanced diet with fruits and vegetables
• Exercise regularly

And remember, regular screenings (like low-dose CT scans) are now recommended for high-risk people—especially smokers over 50.

Living With Lung Cancer: What Can You Expect?

The emotional toll of a lung cancer diagnosis is real. Many patients go through phases of shock, fear, and even guilt—especially if smoking was involved.

But support groups, counselling, and mindfulness can make a huge difference. Advances in treatment mean more people are living longer, even with advanced disease.

It’s not just about surviving anymore—it’s about living with quality, dignity, and hope.

References

1. Lung cancer, World Health Organization (WHO). https://www.who.int/news-room/fact-sheets/detail/cancer
2. American Cancer Society. “What Is Lung Cancer?” https://www.cancer.org/cancer/lung-cancer/about/what-is.html
3. National Cancer Institute. “Lung Cancer Prevention (PDQ®)–Patient Version.” https://www.cancer.gov/types/lung/patient/lung-prevention-pdq
4. Mayo Clinic. “Lung cancer – Diagnosis and treatment.” https://www.mayoclinic.org/diseases-conditions/lung-cancer/diagnosis-treatment/drc-20374628
5. Centers for Disease Control and Prevention (CDC). “Lung Cancer.” https://www.cdc.gov/cancer/lung/index.htm