Lung cancer is a tumour that originates in the airways or the lungs. It is characterised by uncontrolled cell growth in tissues of the lung. If not treated, the growth can spread to other parts of the body. It is one of the most common cause of cancer mortality worldwide for both men and women. Although it predominantly occurs in persons aged 50 to 70 years, it can also be diagnosed in younger populations. Lung cancer is more common in men than in women.
The prevalence in women is also increasing due to increased smoking among women. In the Nairobi cancer registry in 2000, lung cancer was ranked ninth in males at three per cent and 13th in females at 0.3 per cent. There are two main types of lung cancers: small cell lung cancer and non-small cell lung cancer. They form 15 per cent and 85 per cent of lung cancers respectively.
The causes of lung cancer are broadly divided into environmental and genetic. The risk factors include cigarette smoking, which is the primary risk factor. Others include environmental toxins, dietary factors, pre-existing lung diseases and radiation. Cigarette smoking causes 80 to 90 per cent of lung cancers. Smoking increases the risk of lung cancer by 10 times. The development of lung cancer is related to the number of cigarettes smoked, length of smoking and nicotine content.
The risk is lower in those who quit smoking. There is also an increased risk in second hand smoking, that is, inhaling smoke from someone close to you who is smoking. Lung cancer may also occur in 10 to 15 per cent of people who have never smoked. Environmental toxins such as asbestos, arsenic and nickel are other causative agents. There is also a risk among individuals with low fruit and vegetable intake. Genetically speaking, a first degree relative has a two to three-fold excess risk.
The signs and symptoms include respiratory symptoms such as coughing, shortness of breath, coughing of blood and wheezing. Other symptoms include weight loss, weakness and fever. Symptoms due to the spread or the cancer compressing other organs include back pain, bone pain, chest pain, hoarseness of voice and difficulty in swallowing food.
Some of the symptoms may be nonspecific such as fever, weight loss, fatigue and decreased appetite. The common sites of spread of the cancer include brain, bone, liver and kidneys. A few of the patients do not have symptoms and are diagnosed incidentally on routine chest X-rays.
The diagnosis of lung cancer is made by carrying out a tissue biopsy using bronchoscopy. Other tests include sputum cytology, lymph node biopsy, chest X-ray and chest CT scan. Blood tests are also carried out such as blood count, liver function and kidney function tests.
Once the diagnosis of cancer is made, the treatment will depend on the cancer specific cell type, the spread and the person’s performance status. Available treatment includes surgery, chemotherapy and radiation therapy. These modalities of treatments can also be combined for maximum benefit. If the disease is advanced, then palliative care can be offered.