Lung cancer (summary)

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This is a basic article for medical students and non-radiologists

Lung cancer is the most common cancer worldwide and refers to malignancy originating in the airways or pulmonary parenchyma.

Clinical presentation

Patients may be asymptomatic until locally advanced or metastatic disease. The most common presenting symptoms include cough, hemoptysis, dyspnea and chest pain. Systemic symptoms may also be present such as weight loss, fatigue and clubbing.

A locally advanced tumor may cause wheeze and stridor on respiratory examination. A pancoast tumor results in Horner's syndrome, atrophy of hand muscles and shoulder pain.

Pathology

Smoking is the primary risk factor to developing lung cancer. Other risk factors include radiation, asbestos, air pollution, pulmonary fibrosis and genetic factors.

There are four major histological subtypes of lung cancer. These are adenocarcinoma, squamous cell carcinoma, large cell carcinoma and small cell carcinoma. However broadly they are divided as non small cell carcinoma and small cell carcinoma.

Radiographic features

Plain radiograph

Features on chest x ray include new or enalrged focal lesion, widened mediastinum suggestive of lymph node involvement, pleural effusion, atelectasis and consolidation.

CT

A solitary pulmonary nodule is suggestive of malignancy when its borders are irregular/spiculated, located in the upper lobe, thick wall cavitation, solid component within ground glass lesion and growth on follow up imaging. Contrast enhanced CT chest can aid in determining extent of invasion and lymph node involvement.

Pulmonary metastasis is strongly suspected in findings of multiple nodules with known extrathoracic malignancy.

Whole body PET

Used for radiographic staging for potential metastatic disease. However should additional lesions be found, further imaging may be required at the specific site to further characterize the lesion.

Treatment and prognosis

For non small cell carcinoma, staging is required to determine optimum treatment. Surgical resection with curative intent is reserved in patients with early stage disease. Concurrent chemoradiotherapy is used for more extensive disease.

In patients with small cell carcinoma, disseminated disease is present in most patients and thus require systemic chemotherapy. Radiotherapy may also be used in combination.

Prognosis is dependent on the stage of disease at presentation.

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