Lung cancer is the uncontrolled growth of abnormal cells that start off in one or both lungs and arises from the cells of the respiratory epithelium. Cancer that is formed initially in the lungs is known as primary lung cancer and cancer that begins in another area of the body but then spreads to the lungs is called secondary lung cancer. Primary lung cancer is divided into two types which are classified as small cell lung cancer and non-small cell lung cancer. The classification of these two types of primary lung cancer is established by the type of cells in which the cancer starts.
Non-small-cell lung cancer is the most common type of primary lung cancer, as it accounts for more than 80% of cases. It is further divided into 3 subtypes: squamous cell carcinoma, adenocarcinoma and large-cell carcinoma
Squamous cell carcinoma
- Located 2/3 central and 1/3 periphery of the lung
- Arises from large airway epithelial cells
- Strong association with cigarette smoking
- Tends to create obstruction and cause distal atelectasis
- Best prognosis
- Located in the periphery of the lung
- Arises from small airway epithelial cells and type II alveolar cells
- Most common type of lung cancer in non-smokers and more prevalent in women
- Located in the periphery of the lung
- Similar to adenocarcinoma but the lesions tend to be larger
Stages of Non small cell Lung Cancer
Cancer cant be seen by bronchoscopy or imaging scans, Instead the cancer is in the sputum or the bronchial airways 
Abnormal cells are found in the lining of the airway 
Stage IA - Cancer is found only in the lung
Stage IB - The cancer has not spread to the lymph nodes however one of the following is present 1) tumor is larger than 3cm 2) cancer has spread to the main bronchus 3) cancer has spread to the inner membrane that covers the lung 4) part of the lung has developed pneumonitis or collapsed 
Stage IIA (Two senarios)
1) Cancer has spread to the lymph nodes on the same side of the chest as the tumor. One or more of the following is also true - the tumor is not >5cm, cancer has spread to the main bronchus and is 2cm below where the trechea joins, cancer has spread to the inner membrane of the lung, part of the lung has developed pneumonitis or collapsed
2) Cancer has not spread to the lymph nodes and one or more of the following is true - the tumor is >5cm but <7cm, cancer has spread to the main bronchus and is 2cm below where the trechea joins, cancer has spread to the inner membrane of the lung, part of the lung has developed pneumonitis or collapsed 
Stage IIB (Two scenarios)
1) Cancer has spread to the lymph nodes on the same side of the chest as the tumor. One or more of the following is also true - the tumor is >5cm, cancer has spread to the main bronchus and is 2cm below where the trechea joins, cancer has spread to the inner membrane of the lung, part of the lung has developed pneumonitis or collapsed
This stage is divided into 3 subsections depending on the size of the tumor, where it is, and which lymph nodes have cancer 
This stage is divided into 2 subsections depending on the size of the tumor, where it is, and which lymph nodes have cancer 
In this stage the cancer can be any size and may also have spread to the lymph nodes. One or more of the following may also be true a) there is one or more tumors in both lungs b) the fluid that surrounds the lungs and heart also contains cancer c) the cancer has spread to other areas of the body including, but not limited to the liver, brain, kidneys, adrenal glands, and bone 
Small-cell lung cancer is a less common type that accounts for about 15-20% of cases and usually spreads faster than non-small-cell lung cancer. It is often at a more advanced stage when it is diagnosed. This type of lung cancer, which has the strongest association with cigarette smoking, leads to the worst prognosis due to it’s rapid growth.
Lung cancer is one of the most common and serious types of cancer. It is the second highest cancer incidence in both males and females, following prostate cancer in men and breast cancer in women. It is diagnosed in over 41,000 people every year in the UK and is the leading cause of cancer death around the world. In 2008, lung cancer contributed to 13% or 1.6 million of total cancer cases and 18% or 1.4 million cancer-related deaths worldwide. Lung cancer incidence and mortality rates are highest in the United States and developed countries and almost 9 in 10 lung cancer cases occur in people aged 60 years or older.
Cigarette smoking is the leading cause of lung cancer and accounts for about 85% of diagnosed lung cancer patients. Smoking is also most strongly associated with small cell lung cancer and squamous-cell carcinoma. Risk for lung cancer increases with how long a person has been smoking, the amount they smoke and the depth of smoke inhalation. Second-hand smoking also causes lung cancer, but is less strongly associated compared to active smoking. Cigarettes contain more than 60 carcinogens that have been shown to induce cancers. Nicotine causes addiction to cigarette smoking and has been shown to inhibit apoptosis, proliferate cells, and cause angiogenesis in lung tumours.
Cigar and pipe tobacco smoking produces relatively large particles that only reach the upper airways, where cigarette smoking reaches the distal airways because it produces fine particles. Therefore, the risk of lung cancer is lower with cigar and pipe smoking. Smokers of all ages will benefit from the cessation of smoking, but the risk of developing lung cancer will still be increased compared to never smokers. Never smokers are individuals who smoked fewer than 100 cigarettes in their lifetime but this still accounts for 25% of lung cancers worldwide.
Occupational and Environmental exposure
A number of environmental risk factors have been identified, most of which often relates to occupational exposures such as asbestos, tar, soot, and a number of metals such as arsenic, chromium, and nickel. Air pollution has also been linked to increased risk of lung cancer.
Radon gas has been posed as a significant risk factor for lung cancer as well.
There is a genetic susceptibility which increases the risk of lung cancer among first-degree relatives.
There are several other factors that increase the risk of developing lung cancer, and they include:
- Gender (men more predisposed than women)
- Dietary factors
- Individuals with chronic obstructive pulmonary disease
A chest X-ray is usually the first step in diagnosing lung cancer. Tumours usually appear as white/grey masses. Chest X-rays do not always give a clear enough diagnosis, due to the fact that they can’t distinguish between multiple conditions (ex. consolidation and lung abscess)
A CT scan or Computerised (axial) tomography scan, usually carried out after a chest X-ray, takes a series of x-rays at different angles and through the use of computer processors produces a series of cross-sectional images of specific areas of a scanned object, allowing the user to see inside the object. This scan gives a very accurate picture of where a tumour is and its size.
Before having a CT scan, you will be given an injection of a contrast medium. This is a liquid containing a dye that makes the lungs show up more clearly on the scan. The scan is painless and takes 10-30 minutes to complete.
A PET-CT or Positron Emission Tomography computerised tomography,is usually conducted if the results of a CT scan show an early stage cancer. the PET-CT is able to identify where there are active cancer cancer cells. These results are quite useful in helping with diagnosis and treatment.
Before undergoing a PET-CT the individual is injected with a slightly radioactive material. The scanner then works by detecting the radiation given off by the injected radiotracer. 
Bronchoscopy and biopsy
A bronchoscopy is a procedure that allows a physician to remove a small sample of cells from the inside of the lung using a bronchoscope. The bronchoscope is a small tube like device which is passed through the mouth or nose and down through the throat into the airways. This procedure is slightly uncomfortable however it is relatively quick and only takes a few minutes.
Other types of biopsies include:
- Percutaneous needle biopsy
According to the NHS there is currently no national screening program for lung cancer in the UK. The lack of a National screening program is due to the complexity of the tests required to identify lung cancer. No simple, and quick test sensitive enough to outweigh possible risks associated with screening is yet available (ex. radiation exposure during x-rays).
Clinical manifestations that may be presented include:
- Presence of mass irritates the cough receptors in the airway
- Release of sputum
- More common in squamous cell carcinoma and small cell lung cancer (more commonly found in the central airways)
- Obstruction from central airway could also lead to post-obstructive pneumonia and distal atelectasis
- Cancer induced proteolysis and lipolysis leads to loss of muscle and adipose tissue.
- Loss of appetite also contributes to weight loss
- Tumor in the central airway
- Tumor-induced angiogenesis result in blood vessels that are leaky and twisted, leading to easy ruptures and causing hemoptysis
- Obstruction of Airway leading to shortness of breath
- Mechanoreceptors and chemoreceptors are activated in the lungs due to cachexia or hypoxemia/acidosis
- Tumor involving pleural surface causing pleuritic chest pain
Pleural effusion (chest pain, dyspnea)
- Benign pleural effusion may be due to lymphatic obstruction, post-obstructive pneumonitis, or atelectasis
- Malignant pleural effusion occurs when malignant cells and present in pleural fluid
Other signs and symptoms include:
- Swelling of face and arms
- Bone pain
Physiotherapy and Other Management
It has been shown that hydration, autogenic drainage, gentle suctioning, postural drainage, chest physiotherapy, and external oscillation applications can be useful for patients with lung cancer.
Smoking cessation is a very important form of management with lung cancer patients. In addition to education, counselling and support on quitting smoking, there are three main interventions that are used which include:
- Nicotine replacement therapy (NRT): Available in many forms including gum and a transdermal patch. All forms of nicotine replacement increases the rate of quitting by 50-70%.
- Antidepressants: bupropion and nortriptyline are as effective as nicotine replacement therapy
- Nicotine receptor partial agonist: varenicline is more effective than bupropion and NRT.
Aerobic exercise and resistance training have a positive impact on lung functioning including a reduction in airflow obstruction and clearing of airways therefore the improved functional capabilities increase energy levels and the release of sputum. Exercise programs should be supervised by the treating clinical team and should also be discussed with the general practitioner before participating in any exercise program.
Surgery involves a resection of the tumor and some normal tissue around it. This is the first line of choice of treatment for non-small cell lung cancer patients who are medically fit to undergo surgery.
Radiation therapy is a form of treatment that is indicated for patients with stage I, II or III of non-small cell lung cancer. With respect to lung cancer, stages I, II, and III determine various sizes of primary tumor and lymph node involvement without distant metastasis and any distant metastasis is automatically stage IV. It is also used in combination with surgery for non-small cell lung cancer and with chemotherapy for small cell lung cancer.
The first line of treatment for small cell lung cancer, which are often spread upon clinical presentation. It is also indicated for patients with more advanced stage of non-small cell lung cancer to improve prognosis, disease control or for palliative care.
Recent Updates and News
The best way to prevent lung cancer is to quit smoking. The risk of getting diagnosed with lung cancer will decrease the sooner an individual quits smoking. After 10 years of not smoking, the chance of developing lung cancer decreases to half that of someone who smokes.
Research suggests that eating a low-fat, high-fibre diet, including at least five portions of fresh fruit and vegetables and whole grains every day, can help reduce the risk of developing lung cancer, as well as other types of cancer and heart disease.
Studies show that higher levels of physical activity may lower lung cancer risk. It is important to exercise regularly, attempting to perform at least 150 minutes of moderate intensity aerobic activity each week and incorporate muscle strengthening activities two days per week.
Some research has found that taking aspirin may reduce the risk of getting lung cancer. Other studies have found that aspirin may only reduce risk in people who take aspirin daily or may only reduce the risk in men. It is important to check with a doctor before taking aspirin every day as it can damage the lining of the stomach and potentially cause bleeding.
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