Cancer of the lungs is the leading cause of death from cancer. It is one of the most common types of cancer in both men and woman. It is most commonly seen in those over the age of 70 years and rarely under the age of 40 years. Unfortunately lung cancer tends to manifest with symptoms late in the course of the disease and advanced lung cancer has a poor prognosis.
Lung cancer is a serious type of cancer because many people don’t experience symptoms until the disease is advanced and difficult to treat.
Symptoms usually include:
Smoking is the most important risk factor for lung cancer but the incidence of lung cancer is non-smokers is increasing. Other risk factors include exposure to asbestos and radon. , second-hand smoke and likely air pollution, such as from diesel exhaust fumes. These exposures result in acquired gene changes in lung cells causing them to develop in to lung cancer.
People with a family history of lung cancer have an increased risk of developing lung cancer. This is due to a genetic predisposition due to inherited gene changes but this is the reason in a minority of cases.
A diagnosis of lung cancer usually involves obtaining a sample of the tumour to identify the cancer cells by looking at them under a microscope. In cases where this is not possible, or not considered necessary a clinical diagnosis can be made by a multi-disciplinary cancer group.
When the clinical history suggests the possibility of lung cancer radiological imaging is used to identify radiological features of cancer (e.g. a nodule or mass). Computed tomography scans are more sensitive than x-rays at identifying lung cancer and also allow better determination of the size, shape and location, as well as other findings such as the presence of mediastinal or hilar enlarged lymph nodes, or the presence of bone, adrenal or liver metastasis.
Biopsies can be obtained by several methods. These include endobronchial biopsies if there is visible endobronchial lesions or CT guided biopsies of the lung mass. If there are enlarged mediastinal or hilar lymph nodes a transbronchial lymph node biopsy can be obtained using endobronchial ultrasound. If distant lymph nodes are noticed, for example above the clavicle or neck, these can be sample with a ultrasound guided biopsy.
Positron emission tomography (PET) – CT scans are used to detect involvement of the cancer elsewhere in the body and are useful for staging of the disease.
Due to the poor prognosis of lung cancer early detection is important and lung cancer screening can be done for people at high risk.
Treatment of lung cancer depends on the stage of the disease and the type of cancer.
Small cell lung cancer is treated with systemic chemotherapy and radiotherapy. The brain is the most common site of distant spread and in people with limited stage small cell lung cancer preventative cranial irradiation reduces the risk of brain metastasis and improves survival. Because small cell lung cancer spreads rapidly surgery plays a role in only a very small minority of patients where the disease is detected early.
If the tumour is confined to a small area that area of lung can be removed. This can be through removal of a lung segment (segmentectomy), lung lobe (lobectomy) or the whole lung (pneumonectomy).
Localised small tumours can also be treated with stereotactic radiotherapy if surgery is not feasible.
If the lung cancer can’t be treated with surgery or radiotherapy then system chemotherapy, targeted chemotherapy or immunotherapy is considered provided that the person is fit for treatment.