EPIDEMIOLOGY

In 2012, lung cancer occurred in approximately 1.8 million patients and caused an estimated 1.6 million deaths worldwide. In the United States, lung cancer occurs in about 225,000 patients and causes over 160,000 deaths annually. In 1953 and 1985, lung cancer became the most common cause of cancer deaths in men and women, respectively. This has since declined, largely due to a decrease in smoking. Lung cancers are classified as either small cell lung cancers (SCLC) or non-small cell lung cancers (NSCLC). These account for 95% of all lung cancers. This distinction is essential for staging, treatment, and prognosis. The remaining 5% of malignancies that arise in the lung are due to other cell types.

RISK FACTORS 

Smoking has been associated with lung cancer.

Smoking is estimated to account for approximately 90% of lung cancers. For a current smoker of one pack per day for 40 years, the risk of developing lung cancer is approximately 20 times that of someone who has never smoked. Smoke prevention is most important measure to prevent developing lung cancer.

Radiation Therapy can increase the risk of a second primary lung cancer in patients who have been treated for other malignancies. Patient’s being treated for Hodgkin lymphoma and breast cancer demonstrate this increased risk.

Environmental factors such as second-hand smoke, asbestos and metals, pulmonary fibrosis as well as genetic factors also increase the risk of developing lung cancer.

SYMPTOMS

Cough occurs most frequently in patients with squamous cell and small cell carcinomas, present in more than half of lung cancer patients. The new onset of cough should be worrisome in a smoker or former smoker that lung cancer is present.

Haemoptysis is seen in 20-50% of patients with lung cancer. In 5 percent of cases, smokers with haemoptysis and a nonsuspicious or normal chest radiograph a bronchoscopy will diagnose lung cancer.

Chest pain is also a common symptom of lung cancer, present in approximately 20 to 40 percent of patients.  Pain may manifest as a dull, aching or persistent pain and may occur from the mediastinal, pleural or chest wall extension.

Approximately 25 to 40 percent of patients experience Shortness of breath (dyspnoea) at the time of diagnosis of lung cancer. Extrinsic or intraluminal airway obstruction, obstructive pneumonitis or atelectasis, lymphangitic tumour spread, tumour emboli, pneumothorax, pleural effusion, or pericardial effusion with tamponade may result in shortness of breath.

Hoarseness: A smoker may be suffering from laryngeal or lung cancer when there is persistent hoarseness. This is due to malignancy involving the recurrent laryngeal nerve along its course under the arch of the aorta and back to the larynx. ·

Superior vena cava syndrome: A sensation of fullness in the head and dyspnoea are common symptoms resulting from obstruction of the superior vena cava (SVC). Less frequent symptoms include cough, pain, and dysphagia. Dilated neck veins, a prominent venous pattern on the chest, facial oedema, and a plethoric appearance are common physical findings. The cause, level of obstruction, and extent of collateral venous drainage can often be identified by a CT scan.