All About Lung Cancer

Dr.Arun Giri, 3 mins read

Lung cancer is the commonest cancer in males and is leading cause of cancer deaths in the world, among both men and women. There are two broad types of lung cancer, namely small cell lung cancer and non-small cell lung cancer. Non-small cell lung cancer (NSCLC) accounts for about eighty percent of all cases of lung cancer. NSCLC can manifest in different parts of the body such as the cells that line up along the passages of the respiratory tract ( this is called “squamous cell carcinoma”) , in the external part of the lungs ( adenocarcinoma) and in some cases it forms in  tiny air sacks within the lungs called alveoli . This can spread from the lungs to other parts of the body (the spread of cancer from one organ to another is called “metastasis”) Small cell lung cancer (SCLC) accounts for about fifteen percent of lung cancer cases. It grows and spreads quicker than NSCLC. In some cases, a combination of both NSCLC and SCLC cells are found in tumours. Apart from these two, there is also Mesothelioma (caused by exposure to asbestos) and Carcinoid Tumours (begins in hormone producing cells called “neuroendocrine” cells). 

Lung cancer poses difficulty in early detection as the earliest symptoms are fairly innocuous and are ignored by the sufferer and his or her treating physician. Unfortunately, tumours in lungs can grow very quickly and lung cancer is often detected late on. 

Lung Cancer Causes 

In today’s polluted world; anybody can get lung cancer, though majority of cases are attributable to smoking. As the smoke enters the lungs it causes damage leading to structural changes in the cells lining the respiratory tract but the lungs repair themselves but continued inhalation and exposure render their abilities to damage repair ineffective after some time. Upon repeated damage, cells react and behave abnormally and start dividing in unrestricted manner leading to lung cancer. Small-cell lung cancer is more strongly linked to smoking than non-small cell lung cancer. Even second-hand tobacco smoke is a risk factor for lung cancer. Even if one quits smoking, lungs take years to heal. Other agents found around us in our daily lives such as radon (a colourless and odourless radioactive gas found in soil across the world; formed from the decaying of radioactive elements such as uranium), found mostly indoors in our homes and offices no less. Radon can attach itself to dust particles and travel into the lungs in the form of radioactive particles; causing damage and cancer to the lung cells. Other agents such as chromium, cadmium, arsenic, nickel etc are also implicated. Genetic predisposition may also lead to lung cancer and in some cases, there are no clear cause or reason for contracting lung cancer. 

Lung Cancer Stages

There are four stages of NSCLC ,namely  Stage1 (cancer only in the lung ) , Stage 2 ( in the lung and nearby lymph nodes) , Stage 3 (in the lung and lymph nodes in the centre of the chest) , Stage 3A ( found in the lymph nodes but restricted only to the side where the cancer began ) , Stage 3B(the cancer has moved into lymph nodes on the opposite side or towards the collarbone) , Stage 4 (cancer in both lungs and surrounding areas along with other organs of the body). SCLC includes the “limited stage” where the cancer is present in only one lung or nearby lymph nodes and the “extensive stage” where the cancer has travelled through the entire lung into lymph nodes on the opposite side, other lung, bone marrow, distant organs. Statistically; by the time SCLC is detected, 2 in 3 cases are already at an advanced stage. 

Lung Cancer Symptoms 

Both SCLC and NSCLC exhibit similar symptoms. There may be early symptoms such as a prolonged and persistently worsening cough, wheezing, a general weakness and easy fatigue, acutely painful reactions in the chest upon coughing, laughing or deep breathing, coughing up blood or phlegm. As the cancer evolves and spreads, symptoms do too. The symptoms depend on where the cancer has spread into. For instance, if the cancer is in the lymph nodes; lumps develop in and around the neck and collarbone. Headaches and dizziness are experienced in case it has reached the brain or spine, jaundice if it is in the liver, bone pains in the back, hips and ribs in case it has spread into the bone itself.

Lung Cancer Diagnosis 

A number of tests are performed by doctors to diagnose and stage the cancer. Imaging Tests such as an MRI, CT or PET scan, X Ray can reveal abnormalities. Sputum cytology examines the phlegm to determine the presence of cancer cells. Tissue samples can also be collected for biopsy via Bronchoscopy, Mediastinoscopy and Needle insertion and sent to a pathologist for examination. 

Treatment for both NSCLC and SCLC depend on stage at presentation and subtype of the cancer. The survival is considerably higher in NSCLC as SCLC is detected very late and spreads rapidly.

In early stage NSCLC (Stage 1 and 2) Surgery is the preferred treatment option which entails removal of the involved portion of lung and nearby lymph nodes. The procedure is called lobectomy. Surgery may be performed by either open or minimally invasive techniques. For later stage NSLC and almost all stages of Small cell cancers, chemotherapy and radiation treatment, at times together; are effective treatment options. Targeted therapy and immunotherapy are currently being used in some subtypes of lung cancers in late stages. There has been a slew of breakthroughs in anti-lung cancer medicine this last decade and survival rates have improved in developed countries but has largely remained unchanged in developing world due to late diagnosis and lack of awareness and large-scale community-based screening programs.