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Everything You Need to Know About Lung Cancer

Empower yourself with essential knowledge about lung cancer, its causes, and treatment options.

  • 12 Sep 2023
  • 5 min read

Lung cancer is one of the most common types of cancer responsible for high mortality rates worldwide. The condition develops when cancer cells in the lung tissues start multiplying rapidly and uncontrollably. Lung cancer is mainly traceable to regular smoking and prolonged exposure to smoke, and the common lung cancer symptoms include chest discomfort, cough, breathlessness, and wheezing. Continuous or frequent exposure to cigarette smoke can cause lung cell dysplasia, which leads to genetic changes and carcinogenesis. Lung cancer is common worldwide, but developed countries have seen more cases. The cancer can become fatal if not treated at the right time.      

What is Lung Cancer?

Lung cancer affects the lung parenchyma cells or the primary functional cells of the lungs. This cancer type is also known as bronchogenic carcinoma, as it originates from within the lungs' bronchi (tubes) containing alveoli. Around 90% of lung cancer is associated with regular smoking; however, it does not mean a person who never smokes will not develop the disease. Lung cancer has many cellular and molecular subtypes; even so, it is broadly divided into two major types: Small Cell Lung Cancer (SCLC) and Non-Small Cell Lung Cancer (NSCLC), depending on the detection of lung cancer cells under the microscope. 

Types of Lung Cancer

Let us look at the two major types:

  • Small Cell Lung Cancer – Rare form of lung cancer (15% of total cases); strongly linked to cigarette smoking. It is highly aggressive and spreads quickly 
  • Non-Small Cell Lung Cancer – The most common form of lung cancer (85% of total cases), which is divided into the following three types depending on the cells from where the cancer has originated:
    • Lung adenocarcinoma
    • Squamous cell carcinoma
    • Large cell carcinoma

Symptoms of lung cancer

Lung cancer remains asymptomatic mainly until the latter stages, though some mild symptoms may appear initially, which get mostly ignored. However, as the tumour grows, it causes local changes such as increased bronchial compression, leading to chest discomfort. However, as the tumour grows, it causes local changes such as increased bronchial compression, leading to chest discomfort. This is probably the first of lung cancer symptoms and is accompanied by a persistent cough, as observed in some 75% of patients with lung cancer. Lung adenocarcinoma is associated with cough and thin mucus secretion. The following common lung cancer symptoms are usually associated with advanced lung cancer: 

  • Chronic cough with or without mucus
  • Chest pain and breathing problems/dyspnea
  • Blood in cough
  • Recurrent bronchitis and pneumonia
  • Bone pain, if the cancer has spread to the bones
  • Headache
  • Appetite loss and consequent weight loss

Stages of Lung Cancer

The pathologist diagnoses the lung cancer stages as per the typical characteristics of a stage. The Tumour Node Metastasis (TNM) system of determining the cancer stage is followed. Here, “T” represents the location and size of the tumour in the lung, “N” represents the involvement of lymph nodes to determine whether the tumour has started spreading through lymph nodes, while “M” stands for metastasis of the cancerous cells within the lung, i.e. if the cancerous lung cells have spread to distant body organs such as bones, liver, brain, kidney, etc. Lung cancer is staged from I through IV as per the TNM staging system, with minor differences in SCLC and NSCLC. 

SCLC is divided into the following two categories:

  • Limited stage SCLC – The cancerous cells are just within one lobe of the lung and near a lymph node but have not crossed one lobe to another or metastasised to a distant organ.
  • Extensive stage SCLC – The cancerous cells are found not only in one lung but have spread to the other lung and distant organs through the pleural fluid or bloodstream. 

The following five lung cancer stages are observed under NSCLC:    

  • Stage 0 – The tumour occupies a tiny place inside a lung, leaving the surrounding lung tissues normal.
  • Stage I – The tumour has grown to reach a size around 3 cm (for stage I A) to 4 cm (for stage I B) involving a considerable part of lung tissue. But since it has not spread to the nearby lymph nodes, stage I lung cancer symptoms may not be conspicuous.
  • Stage II – The tumour has grown more than 4 cm but has not spread to nearby lymph nodes (Stage II A) and (Stage II B). 
  • Stage III – The tumour becomes cancerous, and the cancer cells start spreading to nearby lymph nodes. This stage can be divided into Stages III A, III B, and III C depending on the tumour size and particular lymph node involvement. This stage is associated with widespread lymph node metastasis, but the cancerous cells have not metastasised to distant organs. 
  • Stage IV – The cancerous cells have spread from one lobe to the other lobe of the lungs or to a nearby organ (Stage IV A) or one/more distant organs (Stage IV B). The cancerous cells in stage IV spread either by entering the lungs' fluid or into the bloodstream. Once the cells enter the bloodstream, they can reach any body part. NSCLC cells can spread to the liver, bones, brain, and adrenal glands.

Complications Associated With Lung Cancer

As the tumour grows, it is usually associated with several complications and side effects linked to lung cancer treatment. These complications are major causes of morbidity and include the following:

  • Complications arising from distant metastasis: In advanced stages, the tumour metastasises to different parts of the body causing various complications. If the tumour metastasises to the brain, it can cause blood clots and stroke. If it metastasises to the kidneys, it can cause kidney stones. It leads to bone pain if metastasised to the bones.
  • Superior vena cava syndrome: As the lung tumour grows it can obstruct blood flow from the upper part of the body to the heart (superior vena cava). Superior vena cava syndrome is associated with swelling of the face, neck, and upper body parts with visually dilated neck veins. This is usually linked to small cell lung cancer.
  • Complications arising from paraneoplastic syndromes: Lung cancer can lead to abnormal parathyroid activity and cause hypercalcemia and related complications such as nausea, anorexia, constipation, and lethargy. Other symptoms associated with neurologic paraneoplastic syndrome include cerebellar ataxia, autonomic neuropathy, encephalomyelitis, and sensory neuropathy. Besides, lung cancer is also linked with hypertrophic pulmonary osteoarthropathy, dermatomyositis, and polymyositis. In advanced stages, lung cancer can impact the adrenal glands and enhance cortisol hormone production, leading to Cushing’s syndrome. 
  • Complications arising from malignant pleural effusion: Abnormal pleural thickening, nodulation, and malignant pleural effusion are linked with advanced lung cancer. Pleural effusion is further associated with various symptoms, including irritating cough, hoarseness, chest pain, and fever.
  • Complications arising from frequent lung infection: A lung cancer patient can experience recurring lung infection that causes bronchitis, pneumonia, etc. 

Also read:

Causes of Lung Cancer

The most notable environmental and habitual factor that causes lung cancer is tobacco consumption and exposure to its smoke. Cigarette smoking alone is accountable for around 90% of lung cancer-related deaths. Other tobacco products, such as cigars or pipes, significantly increase lung cancer risk. Besides tobacco inhalation, the other known causes of lung cancer include:

  • Second-hand smoke
  • Exposure to radon, asbestos, diesel exhaust, silica, chromium, and arsenic
  • Radiation exposure
  • Genetic factors/family history

How is Lung Cancer Diagnosed?

Lung cancer is diagnosed through various techniques, with the doctor recommending specific tests depending upon the signs and symptoms of the stage suspected. The following methods are adopted to diagnose lung cancer:

  • Imaging techniques: Imaging studies are essential in diagnosing lung cancer as they pinpoint where the tumour is growing in the lung. Techniques such as X-Ray, CT-scan, MRI, and PET-scan are employed to analyse lesions in the lung.
  • Bronchoscopy: A bronchoscopy involves using a thin, flexible tube with a light at one end and inserting it through the mouth/nose into the windpipe and further into the lungs. Bronchoscopy also enables ultrasound-guided lymph node examination, and this procedure is called endobronchial ultrasound (EBUS).
  • Tissue or biospecimen assessment: A biopsy is done to confirm the presence of tumour or cancer cells. Biopsy refers to the excision of a small part of the tissue and using that sample for pathological analysis. A pathologist analyses the biopsy test results to confirm the presence of cancer. Other samples used as biospecimen include blood, pleural fluid, and sputum.

How is Lung Cancer Treated?

Multiple treatment options are available for lung cancer, typically depending on the tumour type, stage of cancer, and patient’s overall health. The following include lung cancer treatment options:

  • Surgery - Often considered the main treatment approach, particularly for NSCLC, surgery removes the tumour from the lung and nearby affected lymph nodes. Stage I lung cancer is mainly treated with surgery.
  • Radiation therapy – High beam radiations are used to kill the cancer cells in the lung. Radiation cannot treat metastasised cancer and is thus helpful in the early stages of lung cancer.
  • Chemotherapy – Chemotherapeutic drugs are used to destroy cancer cells. As chemotherapy produces widespread effects, it can be used for higher stages of lung cancer. 
  • Immunotherapy – This therapy utilises specific drugs that can stimulate the immune system to fight lung cancer. 
  • Targeted therapy – This therapy targets cancer-specific genes or proteins and has appeared promising in the treatment of all stages of lung cancer. 

Can Lung Cancer Be Prevented?

Most lung cancer cases occur from environmental exposure to certain chemicals and smoke. Hence, it can be prevented with proper measures to minimise exposure. Quitting smoking is one of the most essential factors in preventing lung cancer. Further, secondhand smokers can always reduce exposure to chemicals and smoke at the workplace by taking informed steps. 

Exposure to radon and asbestos is another important factor, particularly in certain regions. For instance, those living and working in areas near asbestos factories should follow recommended safety measures. Similarly, people living near high chances of exposure to radon should follow such measures. Moreover, following a healthy lifestyle with ample exercise and nutritional food intake can be beneficial and help prevent lung cancer.  

Outlook Towards Lung Cancer

So far, significant technological advances have been achieved to prevent and cure lung cancer. Even so, regular screening plays an important role as early diagnosis can prevent fatalities. The curability of lung cancer depends on the factors listed thus:

  • Routine screening and early diagnosis
  • The overall health of the patient
  • Consulting with doctors about the best treatment approach
  • Analysing and managing side effects
  • Regular follow-ups and timely taken appropriate treatment measures


Coping with lung cancer is always tricky, but a positive mindset and correct treatment choices can help defeat the disease. Most patients get diagnosed at stages II or III, considerably increasing their problems. It is natural for a patient to be stressed out if diagnosed positively, which gets exacerbated by costly treatment charges. To steer clear of such unwanted situations, obtaining health insurance will surely alleviate your stress and help to better focus on your treatment.   

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