Lung Cancer
Lung cancer is the most common cancer globally and has been for several decades, with an estimated 1.8 million new cases in 2012 (Guo et al., 2017). The rates of lung cancer are high in Central Europe, Eastern Europe and Eastern Asia, but low in the Middle and West Africa (Morampudi, Das, Gowda & Patil, 2017). Even with these high numbers, lung cancer is underdiagnosed, mainly due to a lack of effective diagnostic tools for early detection, so people are not often diagnosed until at an advanced stage of disease (Zarogoulidis, Baka, Labaki, Lazaridis & Trakada, 2017).
The main types of lung cancer include (Osiecki, 2012, p450):
Symptoms of lung cancer can depend on the type. Carcinoid tumours often cause no symptoms other than a blockage in the lungs to cause coughing, shortness of breath, and coughing up blood. If a carcinoid is secreting hormones, it can mimic other conditions related to high levels of those hormones or hormone imbalance. These related conditions are called paraneoplastic syndromes (Osiecki, 2012, p450; American Cancer Society, 2017a).
Small Cell Lung Cancer symptoms include coughing, coughing blood or rust coloured mucus, chest pain which is worse with deep breathing or coughing, weight loss and loss of appetite, shortness of breath, feeling weak or tired, frequent respiratory infections, wheezing and others (American Cancer Society, 2017a)
Non-Small Cell Lung Cancer symptoms are similar to Small Cell Lung Cancer (American Cancer Society, 2017b).
The risk factors of lung cancer include the following:
The main types of lung cancer include (Osiecki, 2012, p450):
- Carcinoid lung cancer - these are a distinctly different type, as the tumours sometimes secrete bioactive compounds such as hormones which have effects on the body. Carcinoid tumours are a slow growing form and account for just 2% of lung cancers.
- Small Cell lung cancer (SCLC) - is the most aggressive form, comprising about 13% of lung cancers. It is aggressive as it has a tendency to mutate or become less responsive to medical treatments, probably as a result of long-term exposure to carcinogens in cigarette smoke (Tartarone, Giordano, Lerose, Rodriquenz, Conca & Aieta, 2017).
- Non-Small Cell lung cancer (NSCLC) - the most common type, being about 86% of all lung cancers, and comprises a group of different types of tumours including adenocarcinomas and squamous cell carcinomas and others (Charkiewicz et al., 2017).
Symptoms of lung cancer can depend on the type. Carcinoid tumours often cause no symptoms other than a blockage in the lungs to cause coughing, shortness of breath, and coughing up blood. If a carcinoid is secreting hormones, it can mimic other conditions related to high levels of those hormones or hormone imbalance. These related conditions are called paraneoplastic syndromes (Osiecki, 2012, p450; American Cancer Society, 2017a).
Small Cell Lung Cancer symptoms include coughing, coughing blood or rust coloured mucus, chest pain which is worse with deep breathing or coughing, weight loss and loss of appetite, shortness of breath, feeling weak or tired, frequent respiratory infections, wheezing and others (American Cancer Society, 2017a)
Non-Small Cell Lung Cancer symptoms are similar to Small Cell Lung Cancer (American Cancer Society, 2017b).
The risk factors of lung cancer include the following:
- Ethnicity - Rates of lung cancer are high in certain cultures, such as a large increase seen in Japan and Central Europe in recent years, and is also higher in dark-skinned races, and lower socioeconomic areas (Osiecki, 2012, p451).
- Diet – Low intakes of various nutrients such as vitamins E and C, selenium, zinc and retinoids can reduce immune system and respiratory function, and antioxidant levels. (Osiecki, 2012, p450).
- Smoking - this is the main factor in lung cancer incidences, but 25% of affected patients are non-smokers (Guo et al., 2017). Smoke from cigarettes and cigars contains many free radicals and carcinogens, which causes oxidative stress, DNA damage and impaired immune function. This can occur even from passive smoking (exposure to cigarette smoke from other people). The greater the amount and the longer the time someone smokes increases the risk of lung cancer (Osiecki, 2012, p450).
- Infections - infectious diseases such as human papillomavirus (HPV) and Epstein-Barr Virus (EBV) can be causative agents in a variety of human cancers, including in approximately 22% of lung cancer (Guo et al., 2017; Osiecki, 2012, p450).
- Cooking oil fumes - breathing in fumes from cooking oil can lead to DNA damage and lung cancer development (Osiecki, 2012, p450).
- Hormone Replacement Therapy (HRT) – taking a combination of oestrogen and progesterone HRT treatment over a period of more than 10 years can increase the risk of lung cancer (Osiecki, 2012, p451).
- Environmental toxins – occupational or environmental exposure to toxins such as radon, asbestos, toxic metals, or air pollution (Guo et al., 2017). Radon is a naturally occurring radioactive gas, which can be found in cigarettes and in many homes and other buildings. Radon exposure is the second highest cause of lung cancer in the USA. Asbestos is used as a fire retardant and insulation in many homes and buildings, and exposure to its fibres can lead to mesothelioma. Air pollution, especially near heavy traffic and industries and can contribute to about 5% of lung cancer (American Cancer Society, 2017b). High levels of the heavy metals cadmium and lead intake are linked to lung cancer (Osiecki, 2012, p450).
- Genetics – genetic changes can lead to abnormal cell growth and sometimes, cancer. Inherited genetic mutations can increase the risk, even if you don't smoke. Some people have a reduced ability to detoxify or eliminate certain cancer-causing chemicals from their body, due to genetic mutations. Generally, lung cancer arises from acquired genetic changes, such as to tumour suppressor genes or other genes (American Cancer Society, 2017b).