How Lung Cancer Develops

Lung cancer begins when cells lining the airways or lung tissue accumulate DNA damage that disrupts normal cell growth controls. Instead of dying off as old cells normally do, these abnormal cells multiply and can form a tumor. Over time, cancer cells may break away, travel through the lymphatic system or bloodstream, and establish new tumors in distant organs — a process called metastasis.

The two primary categories of lung cancer differ in important ways. Non-small cell lung cancer (NSCLC) — which includes adenocarcinoma, squamous cell carcinoma, and large cell carcinoma — typically grows more slowly. Small cell lung cancer (SCLC) is less common but spreads aggressively and is almost exclusively linked to heavy tobacco use.

Because the lungs are large organs with considerable reserve capacity, early-stage tumors rarely trigger noticeable symptoms. This biological reality is a key reason why lung cancer is so often diagnosed at an advanced stage.

Lung Cancer Is Not One Disease

The term 'lung cancer' covers several biologically distinct diseases that behave differently and require different treatments. Knowing which subtype a patient has — and whether specific gene mutations are present — is now essential to selecting the most effective therapy. This is why biopsy and molecular testing are standard steps following any suspected diagnosis.

Why Older Adults Face Higher Risk

Age is an independent risk factor for most cancers, and lung cancer is no exception. Decades of cumulative exposure to carcinogens — whether from tobacco smoke, radon gas, asbestos, or air pollution — increase the probability that DNA damage will accumulate to a cancer-causing threshold. The American Cancer Society notes that the median age at lung cancer diagnosis is approximately 70.

Tobacco history is the dominant risk factor, but radon — a naturally occurring radioactive gas that seeps into homes from soil — is the second leading cause of lung cancer in the U.S. and often goes unrecognized. Occupational exposures common in older generations, such as asbestos in construction or silica dust in mining, also contribute to lifetime risk. For a broader look at frequently overlooked contributors, see cancer risk factors older adults most often miss.

Genetic factors also play a role for some individuals. Certain inherited gene variants can influence susceptibility, as discussed in our overview of cancer risk and genetics.

~236,000

New lung cancer diagnoses in the U.S. annually

According to the American Cancer Society's estimates, lung cancer remains the second most commonly diagnosed cancer in both men and women in the United States.

~70 years

Median age at lung cancer diagnosis

The American Cancer Society reports that most people diagnosed with lung cancer are in their late 60s or older, reflecting decades of cumulative exposure to risk factors.

~2nd leading

Radon as cause of lung cancer deaths

The U.S. Environmental Protection Agency estimates radon gas exposure is the second leading cause of lung cancer in the U.S., responsible for approximately 21,000 deaths per year.

Recognizing Warning Signs

One of the most important things older adults can know about lung cancer is that early tumors are often silent. Symptoms, when they do appear, are frequently attributed to more common conditions like a persistent cold, acid reflux, or age-related breathlessness. This delay in recognition contributes to later-stage diagnoses.

Warning signs that deserve medical attention include:

  • A new or changing cough that persists beyond three weeks
  • Coughing up blood, even in small amounts
  • Unexplained shortness of breath or wheezing
  • Persistent chest, shoulder, or back pain not linked to injury
  • Hoarseness without an obvious cause
  • Unexplained weight loss or fatigue
  • Recurrent respiratory infections such as bronchitis or pneumonia

None of these symptoms confirm a lung cancer diagnosis — each has multiple possible explanations. However, any symptom that is new, persistent, or unexplained is a reason to consult a healthcare provider promptly.

Don't Wait for Symptoms to Talk to Your Doctor

If you are between 50 and 80 years old with a significant smoking history, ask your healthcare provider whether low-dose CT lung cancer screening is appropriate for you. Screening is designed to find cancer before symptoms develop, when treatment is most effective. Eligibility is based on age, smoking history, and current health — your provider can help you assess your individual situation.

Screening, Diagnosis, and What Comes Next

For high-risk older adults, low-dose computed tomography (LDCT) scanning offers a meaningful opportunity for earlier detection. The U.S. Preventive Services Task Force recommends annual LDCT screening for adults aged 50 to 80 with a 20 pack-year or greater smoking history who currently smoke or quit within the past 15 years. Importantly, screening is a preventive tool, not a diagnostic test — a positive finding triggers further evaluation, not immediate treatment. For a broader discussion of recommended cancer screenings, see cancer screenings recommended for adults over 50.

When lung cancer is suspected, diagnosis typically involves imaging (CT scan, PET scan), bronchoscopy, or biopsy to confirm the presence of cancer cells and determine the subtype and stage. Molecular testing of tumor tissue has become standard practice and can reveal specific genetic mutations that guide treatment selection.

Treatment options span surgery (for early-stage NSCLC), radiation therapy, chemotherapy, targeted therapies, and immunotherapy. The right approach depends on cancer type, stage, and the patient's overall health — a conversation best had directly with an oncologist.

Lung cancer is not the only malignancy that disproportionately affects older adults. Bladder cancer is another common diagnosis in adults over 65 that benefits from early awareness.

This article is for general informational purposes only and is not a substitute for professional medical advice, diagnosis, or treatment. Always consult a qualified healthcare provider with questions about your health or symptoms.