According to statistics released by the World Health Organization, lung cancer is the most common cancer globally. Additionally, it is the leading cause of cancer-related deaths worldwide. According to statistics released in 2018 by the American Lung Association, there were more than two million new cases each year. Out of these, 1.8 million died due to lung cancer advancement or complications. This number is slowly rising due to an increase in the number of smokers.
By definition, cancer is a disease characterized by excessive proliferation of cells and their unregulated growth. Consequently, the cells invade other neighboring tissues. Lung cancer biologically occurs in the two porous structures called lungs found in the chest that are responsible for respiration. The risk of developing lung cancer is 30 times more in smokers than non-smokers.
Lung cancer is asymptomatic, especially in the early stages. However, as it progresses, it may present with:
The exact cause of lung cancer is not known. However, a recent study correlates lung cancer with certain carcinogens found in tobacco, asbestos, and radon. When an individual smokes, the immune cells work to remove the particles from the lung. However, over time, the cells become damaged; therefore, they cannot eliminate the particulate matter. The accumulated particulate matter induces the production of chemokines, growth factors, multiple neuropeptides, and other inflammatory mediators that interrupts the normal cell cycle regulation.
Other Risk Factors That Predispose An Individual To Lung Cancer are:
Tobacco smoke increases the chances of developing lung cancer by 300% in smokers. Also, recently there have been cases where passive or secondhand smokers develop lung cancer. The American Lung Association has reported over 7,000 lung cancer cases due to passive smoking, especially among family members of chronic smokers.
Radon is a chemical found in the majority of the building materials found in homes and offices. The World Health Organization attributes about 30% of lung cancer-related deaths to radon exposure. Additionally, research has linked asbestos as one of the leading cause of mesothelioma, a type of lung cancer.
Other chemical substances linked to lung cancer are arsenic, chromium, nickel, cadmium, uranium, and some petroleum products like coal.
If one of your family members had a history of lung cancer, you are more predisposed to developing lung cancer. The percentage of predisposition increases when the family member was a 1st or 2nd-degree relative.
Previously, it was thought that taking beta carotene supplements lowered the propensity to develop lung cancer. However, recent studies revealed that beta carotene increases the risk of developing lung cancer in smokers and alcoholics.
Generally, women are more likely to develop lung cancer compared to men at an early age. However, as they grow old, the population dynamics changes, where older males are more likely to develop lung cancer than older females. Also, blacks and Hispanics are more predisposed to getting lung cancer due to their genetic makeup.
A prolonged period of some viral or bacterial infection without treatment may propagate the development of lung cancer.
Lung cancer is broadly classified into small cell lung cancer (SCLC) and non-small cell lung cancer (NSCLC). These two types of cancer differ in their etiology, distribution, pathogenesis, and treatment.
It is the most common type of lung cancer, responsible for 80-85% of lung cancer cases. NSCLC is common among smokers. Other causative agents are asbestos, radon, metal dust, arsenic, and petroleum products. The pathogenesis of NSCLC originates from the lung's epithelium and progresses to other regions in the lung. NSCLC is further sub-classified into:
Adenocarcinoma accounts for about 30% of all non-small cell carcinoma. This type of cancer begins at the alveolar and ascends the bronchial tree. Adenocarcinomas develop slowly, and it takes a long time before the signs and symptoms present. Additionally, this type of lung cancer is common in both smokers and non-smokers.
This type of lung cancer starts from the epithelial lining of the lung, particularly in the airways.
This type of lung cancer involves the undifferentiated cells of the lung. Also, it is tough to treat because it is very aggressive.
This type of cancer occurs in 15% of individuals diagnosed with lung cancer. It grows more rapidly; therefore, it is more aggressive. However, the SCLC responds well to chemotherapy and radiation therapy.
The small cell lung carcinoma is further sub-classified into two, namely the small cell carcinoma, also known as the oat cell carcinoma, and the combined small cell carcinoma. SCLC is associated with paraneoplastic syndrome.
Another type of lung cancer is bronchial carcinoids. They are rare and occur in about 5% of individuals diagnosed with lung carcinoma. This type of cancer is aggressive, and it is predominant among the younger population under 40 years. It is not linked to smoking. Additionally, this type of cancer secretes hormonal-like substances and can be surgically treated.
Lung cancer can metastasize to other organs through the lymphatic system or the bloodstream. Metastasis occurs when the cancer is categorized as stage IV lung cancer. Also, lung cancer can result from metastasis from another site.
When a loved one is diagnosed with lung cancer, the doctor says that they have Stage II, stage III, or stage IV lung cancer. In most scenarios, the patient or family member does not understand what these terms mean. Here is a list that will clarify.
Cancers are categorized according to the TNM system, where T stands for tumor size, N stands for nodular involvement, and M stands for metastasis.
For SCLC, it is classified into a limited stage and an extensive stage. In the limited-stage, the cancer is confined to the lung where it started and the surrounding lymph nodes. In the extensive stage, the cancer has spread from origin to other distant lymph nodes and organs.
Diagnosis involves extensive history taking, imaging techniques, tissue and fluid biopsy, and bronchoscopy.
Extensive history taking will highlight if an individual was a smoker or their occupation exposed them to the possible carcinogens. It will also outline the familial and genetic predisposition of the individual to lung cancer.
The doctor may recommend diagnostic imaging techniques like X-rays, ultrasound, and magnetic resonance imaging. A CT scan gives a more detailed image of the extent of the spread of the cancer. Pet scans involve the use of radioactive components to identify the location of the cancerous mass.
Sputum cytology and fluid extracted from needle aspiration may reveal cancerous cells. Tissue biopsy is the gold standard technique in identifying cancerous cells. It involves the surgical extraction of the suspected cancerous mass and extensive laboratory investigation. Other techniques are bronchoscopy, mediastinoscopy, and thoracoscopy.
Depending on the lung cancer stage, a specialist may recommend treatment using one or a combination of the therapy listed below.
It is the most appropriate treatment approach for a consolidated cancerous mass in the early stages. It involves partial or total surgical removal of a lung.
This involves illuminating the chest region with a high-intensity laser beam or a radioactive compound to kill the cancerous cells. It is recommended after surgical removal to kill the remaining cancer cells.
Whether it is through intravenous or oral agents, chemotherapy has proven a useful technique in reducing the tumor's size. In recent drug development, the chemotherapeutic agents are developed to target the cancerous cell while sparing the normal healthy cells. This is known as targeted therapy.
Immunotherapy entails techniques that will boost your immunity.
It is for cancer patients who are in stage IV lung cancer unresponsive to all types of therapy. Symptomatic management aims at making the patient more comfortable and lessens the pain. Patients are given analgesics and oxygen therapy as they are having difficulties in breathing.