Lung Cancer: Types, Symptoms, Causes & PET CT Role in Diagnosis

Lung cancer develops when abnormal cells in one or both lungs grow uncontrollably and form tumors. It often starts in the lining of the bronchi or lung tissues and may go unnoticed in its early stages due to subtle or absent symptoms. The lungs play a crucial role in supplying oxygen to the bloodstream and removing carbon dioxide from the body. Because lung cancer often doesn't produce symptoms early on, it's frequently diagnosed at an advanced stage. Diagnostic evaluation of lung cancer includes a variety of tools such as chest X-ray, CT scan, MRI, PET-CT, bronchoscopy, and biopsy. PET CT is especially effective in diagnosing lung cancer as it combines metabolic and anatomical imaging, allowing for early detection, staging, and treatment planning.

What is Lung Cancer?

Lung cancer refers to the abnormal and uncontrolled growth of cells in the lungs that leads to tumor formation. It is broadly categorized into non-small cell lung cancer (NSCLC) and small cell lung cancer (SCLC). NSCLC is more common, while SCLC is more aggressive and fast-spreading. Lung cancer is one of the leading causes of cancer-related deaths worldwide. While smoking is the primary risk factor, lung cancer can also occur in non-smokers due to other environmental or genetic factors. Early detection plays a crucial role in improving outcomes, and PET CT is a vital imaging modality for staging and guiding treatment strategies.

What are the Different Types of Lung Cancer?

Lung cancer is mainly classified based on the appearance of cancer cells under the microscope:

• Non-Small Cell Lung Cancer (NSCLC):
• Adenocarcinoma
• Squamous cell carcinoma
• Large cell carcinoma
• Small Cell Lung Cancer (SCLC): Rapidly growing cancer that spreads quickly
• Lung Carcinoid Tumors: Rare, slow-growing cancers
• Metastatic Lung Cancer: Cancer that spreads to the lungs from other parts of the body

What are the Symptoms of Lung Cancer?

Lung cancer symptoms may not appear until the disease has progressed. Common symptoms include:

• Persistent cough that doesn’t go away
• Chest pain or discomfort
• Shortness of breath
• Unexplained weight loss
• Coughing up blood (hemoptysis)
• Fatigue and weakness
• Hoarseness
• Frequent lung infections (like pneumonia or bronchitis)
• Swelling in the face or neck

What are the Causes of Lung Cancer?

While the exact cause of lung cancer may vary, known risk factors include:

• Smoking (primary cause) – both active and passive smoking
• Exposure to radon gas
• Asbestos exposure
• Air pollution
• Chronic obstructive pulmonary disease (COPD)
• Family history of lung cancer
• Exposure to carcinogens (arsenic, chromium, nickel, etc.)
• Previous radiation therapy to the chest
• Genetic mutations

What Does PET CT Scan Detect in Lung Cancer?

PET CT (Positron Emission Tomography – Computed Tomography) is a powerful tool in the detection and management of lung cancer. It helps in:

• Early detection of suspicious lung nodules
• Differentiating between benign and malignant tumors
• Staging of lung cancer to determine if it has spread to lymph nodes or other organs
• Assessment of tumor metabolism
• Monitoring treatment response (chemotherapy, radiation, or surgery)
• Detecting recurrence of cancer after treatment
• Identifying ideal biopsy sites
• Planning for surgery or radiation therapy

PET CT combines functional imaging with anatomical imaging, offering detailed information on both metabolic activity and tumor location, which makes it indispensable in the management of lung cancer.

What are the Different Types of Tests used for the Detection of Lung Cancer Other Than PET CT Scan?

In addition to PET CT, a range of other tests are used to detect and assess lung cancer, including:

• Laboratory Tests

• Complete blood count (CBC)
• Tumor markers (CEA, NSE)
• Sputum cytology (examining mucus for cancer cells)

• Imaging Tests

• Chest X-ray
• CT (Computed Tomography) scan
• MRI (Magnetic Resonance Imaging)
• PET CT scan
• Bone scan (if metastasis suspected)

• Procedures/Surgical Tests

• Bronchoscopy (to examine airways and collect tissue samples)
• Needle biopsy or fine needle aspiration (FNA)
• Thoracoscopy or mediastinoscopy
• Lung tissue biopsy
• Pleural fluid analysis (if fluid is present around lungs)

Conclusion

Lung cancer is a serious condition that arises from the uncontrolled growth of abnormal cells in the lungs, potentially spreading to other parts of the body. It is often asymptomatic in the early stages and is frequently diagnosed only when it becomes advanced. Risk factors include smoking, exposure to harmful substances, family history, and environmental pollutants. Common symptoms include persistent cough, breathlessness, and chest pain. Accurate and early detection of lung cancer significantly improves treatment success. Diagnostic options include imaging techniques, laboratory tests, and biopsy procedures. Among these, the PET CT scan stands out due to its ability to detect functional and structural changes in the lungs at the cellular level. This makes PET CT an essential tool for staging, treatment monitoring, and recurrence detection in lung cancer.