The lungs are two sponges like organs in the chest cavity. The right lung is divided into 3 sections, called lobes. Left lung has two lobes. It is smaller to accommodate the heart. Air with the breath goes into the lungs through trachea (wind pipe). The trachea divides into tubes called the bronchi, which divides further into smaller branches called the bronchioles. At the end of the bronchioles are tiny air sacks known as alveoli. Many tiny blood vessels run through the alveoli absorbing oxygen from the inhaled air into the blood stream and releasing carbon dioxide. Taking in oxygen and releasing carbon dioxide are the two main functions of the lung. A lining called pleura surrounds the lungs. This slippery lining protects the lungs and help them slide back and forth as they expand and contract, during breathing. Most lung cancers start in the lining of the bronchi, frequently in the periphery of the lungs. Lung cancers are thought to develop over a period of many years. First, there may be areas of precancerous changes in the lungs. These changes do not form a mass or tumor, or cannot be seen or x-ray, and do not cause any symptoms. Lung cancer is most frequently seen in industrialized nations. This cancer is found in both sexes. This cancer was not as widely spread as it is today 100 years ago, now it is one of the major cancers affecting people. It is found mostly in people above 40 years of age.
(2) Types of lung cancers:-
There are two major types of lung cancers.
(1) Small cell lung cancer – About 15 to 20% of all lung cancers are small cell lung cancers, named for the small round cells that make up these cancers. Small cell lung cancer tends to spread widely through the body. This is important because ir means that treatment must include drugs to destroy the wide spread disease. The cancer cells can multiply quickly, form large tumors, and spread to lymph nodes and other organs such as the bones, brain, adrenal glands, and liver. This type of cancer also starts in the bronchi near the centre of the chest. Small cell lung cancer is almost always caused by smoking.
(2) Non-small cell lung cancer – The majority of lung cancers are non-small cell type. There are three sub types of this cancer. The cells in these types differ in size, shape and chemical make-up.
(a) Squamous cell carcinoma – About 25-30% of all lung cancers are of this type. They are associated with a history of smoking.
(b) Adeno carcinoma – This type of cancer accounts for about 40-45% of all lung cancers. It is usually found in the outer region of the lung.
(c) Large cell carcinoma – This type of lung cancer accounts for about 10 to 15% of all lung cancers. It may appear in any part of the lung, and it tends to grow and spread very quickly.
(3) Symptoms: –
Lung cancer produces symptoms at a very late stage of development, till it has spread very far.
(a) A cough that does not go away – 75% of patients complain of coughing at initial stage. If coughing persists more than three weeks x-rays should be taken. Smokers, who have chronic bronchitis, should remain more alert and should do periodic screening.
(b) Chest pain – Often aggravated by deep breathing, coughing and even laughing.
(c) Bloody or rust coloured sputum – Blood or pus in sputum could indicate lung cancer, timely screening helps early diagnosis. If a major vein or artey is affected by cancer, sudden burst can cause immediate danger to the patient’s life.
(d) Weight loss and loss of appetite – Any unexplained weight loss or loss of appetite is a sign to be taken seriously.
(e) Shortness of breath and hoarseness of speech – As cancer spreads in lungs the capacity of the lungs to breathe air diminishes, thus causing shortness of breath frequently, speech also changes.
(f) Recurring infections – Infections of pneumonia and bronchitis, which are uncured even after a lot of treatment may indicate lung cancer.
When the cancer has spread to other parts of the body the symptoms may present in the following manner.
(i) Bone pain.
(ii) Neurological changes such as weakness or numbness of limbs, dizziness, or recent onset of a seizure.
(iii) Jaundice yellow coloring of the skin and the eyes.
(iv) Masses near the surface of the body, due to cancer spreading to the skin or to the lymph nodes in the neck, or above the collarbone.
These symptoms could be the first warning signs of a lung cancer. Many of these symptoms can result from other causes or from non-cancerous diseases of the lungs, or heart, and other organs.
(i) Horner’s syndrome – Cancer of the upper part of the lungs may damage a nerve that passes from the upper chest into neck. These are at times also called pancost tumors. Their most common symptom is severe shoulder pain. Horner’s syndrome is the medical name for the group of symptoms consisting of drooping or weakness of one eyelid, reduced or absent perspiration on the same side of face, and a smaller pupil on that side of the face.
(ii) Paraneoplasic syndrome – Some lung cancers may produce hormones like or other substances that enter the blood stram and causes problems with distant tissues and organs, even though the cancer has not spread to those tissues or organs. These problems are called paraneoplasic syndromes. Sometimes these syndromes may be the first symptoms of early lung cancer. Because these symptoms affect other organs, patients and their doctors may suspect at first that disease other than lung cancer caused them. Patients with small cell lung cancer and those with non-small cell lung cancer often have different paraneoplastic syndromes. The most common paraneoplastic syndrome associated with small cell lung cancer.
(iii) SIADH – ( Syndrome of inappropriate antidiuretic hormones ) causes salt levels of the blood to become very low. Symptoms of SIADH include fatigue, loss of appetite, muscle weakness or cramps, nausea, vomiting, restlessness, and confusion. Without treatment, severe cases may lead to seizure and coma.
(iv) Production of substances that cause blood clots to form – most of these clots interrupt blood flow to the limbs, lungs, brain, or their internal organs.
(v) Unexplained loss of balance and unsteadiness in arms and legs movement (cerebeller degeneration ) – The most common paraneoplastic syndrome caused by non-small cell cancer are. 1- Hypercalcemia (sometimes painful) of certain bones, especially those in fingertips. The medical term for this is hypertrophy osteoarthropy. 2- Production of substances that activates the clotting system, leading to blood clots. 3- Excess breast growth in men. The medical term for this condition is gynecomastia.
(vi) Easinophelis – Easinophil counts if are excess in blood it may indicate lung cancer.
(vii) Neuromyipathies – The patient feels swelling of muscle tissues and general weakness of the muscles. Sense of touch is lost in some parts of the body. When all treatments fail lung x-ray sometimes reveals the spread of lung cancer. As cancer is treated successfully these symptoms disappear.
(viii) Myesthenia gravis – This disorder can also be caused due to lung cancer. Where muscle activity is lost due to weakness. If eyelids are affected one loses control of movement of them, eyes get closed inadvertently. If throat muscles get affected breathing becomes difficult, chewing and swallowing of food also becomes difficult.
(ix) These are some of the common complaints of patients affected with lung cancer.
- General weakness in the body.
- Diminished strength and skin glow.
- Clubbing of nails.
- Irregular breathing.
- Neck tumors are seen.
- Enlargement of liver.
- Joint pains in the body.
- Bone fracture without any visible cause.
(4) Risk factors: –
(i) Tobacco smoking – Tobacco is the most common risk factor for lung cancer. In the past lung cancer was not so common as it is today. Phenomenal increase in smoking due to mass production and marketing of cigarettes has increased the instances of lung cancer drastically. Smoling is equally dangerous even if smoke is inhaled indirectly i.e. passively. Even after the smoker has stopped smoking, the damaged lung tissues take 10 to 15 years to return to normal condition. Even after that period the risk reduction is only third of what it would be if the person had not stopped smoking.
(ii) Asbestos – Exposure to asbestos fibres is an important risk factor for lung cancer. And if a person is smoking and also is exposed to asbestos inhalation, the risk of lung cancer is 50 times higher than that of any other person. Both smokers and non-smokers exposed to asbestos have a great risk of developing lung cancer that starts from pleura. This cancer is called mesothelioma.
(iii) Radiation exposure – When uranium breaks down naturally it produces radon, a radio-active gas that is not dangerous outdoors, but indoors it can be very dangerous if inhaled directly.
(iv) Cancer causing agents in the workplace – Radioactive ores such as uranium, inhaled chemicals or minerals such as arsenic, beryllium, vinyl chloride, nickel chromates, coal products, mustard gas, and chloromethylether, fuel fumes from gasoline etc., exhaust fumes inhalation. In cotton industry fine dust particles of cotton entering the lungs through breathing can cause cancer. Workers in stone mines face the danger of inhaling stone dust. This gets settled in the lungs ultimately resulting in cancer. People working in farms are exposed to minute dust particles and pollen from plants which causes lung cancer in the long run.
(v) Radiation therapy – People exposed to radiation therapy for chest are at high risk for lung cancer. The most at risk are women being treated for breast cancer.
(vi) Mineral exposure – Talc mineral contains asbestos amd exposure to talc dust increases the risk of lung cancer. Also minerals like silicosis and berylliosis also have a higher risk of lung cancer.
(vii) Family history, diet and air pollution have a major role to play in the developed of lung cancer.
(5) Diagnosis as per modern science: –
- CT scan
- Sputum cytology
- Radiologically occult cancer – This type of cancer is detected in other biological tests, but X-ray fails to detect this cancer.
- Lung profusion scan – With the help of this scan the physician can determine the spread of this cancer.
(6) Staging and Grading: –
Stage 0:- The cancer is found only in the layer of cells lining the air passages. It has not
invaded other lung tissues nor spread to lymph nodes or distant sites.
Stage IA:- The cancer is no larger than 3 centimeters, has not spread to the membranes that surround the lungs, does not affect the main branches of the bronchi and has not spread to lymph nodes or distant sites.
Stage IB:- The cancer is larger than 3 cm, or involves a main bronchus, but is not near the carina or it has spread to the pleura or the cancer is partially clogging the airways. It has not spread to lymph nodes or distant sites.
Stage IIA:- The cancer is no larger than 3 centimeters, has not spread to the membranes that surround the lungs, does not affect the main branches of the bronchi. It has spread to nearby or hilar lymph nodes, but not to distant sites.
Stage IIB:- The cancer is larger than 3 cm, or involves a main bronchus, but is not near the carina or it has spread to the pleura or the cancer is partially clogging the airways. It has spread to nearby lymph nodes, but not to distant sites, it has spread to the chest wall or the diaphragm, the mediastinal pleura, or membranes surrounding the heart, or it invades a main bronchus and is close to the carina or it has grown into the airways enough to cause an entire lung to collapse or to cause pneumonia in the entire lung. It has not spread to lymph nodes or distant sites.
Stage IIIA:- The cancer can be any size, or involves a main bronchus, but is not near the carina or it has spread to the pleura or the cancer is partially clogging the airways. It has
spread to nodes in the middle of the chest (mediastinum), but not to distant sites.
Stage IIIB:- The cancer can be of any size. It has spread to lymph nodes around the collarbone on either side, or to hilar or mediastinal lymph nodes on the side opposite
the cancerous lung, it has spread to the mediastinum, the heart, the windpipe (trachea), the esophagus (tube connecting the throat to the stomach).
Stage IV:- The cancer has spread to distant sites.