Lung cancer

Lung cancer remains the commonest killing cancer in both men and women in the developed world, and is increasingly common in developing countries, although as a result of decreased tobacco consumption in Western countries there has been a considerable reduction in the incidence amongst men over the last 20 years, and a slowing down in incidence in women over the last few years. Nevertheless, lung cancer in women is commoner than breast cancer in some Western countries. There are several important industrial associations with lung cancer, in particular asbestos, but tobacco remains by far the most important cause.

Pathology—there are four main cell types of lung cancer, of which adeno-, squamous and large cell varieties comprise non-small-cell lung cancer (NSCLC), with the more aggressive type—small cell—being regarded as a separate entity from the point of view of staging and treatment.

Clinical features—there are no particular presenting features that strongly suggest a new lung cancer, hence it is a disease that often presents late and with widespread metastatic disease. Symptoms and signs can be subdivided into (1) intrapulmonary symptoms—cough (most commonly), haemoptysis (most dramatically), wheeze, chest discomfort, and breathlessness (rare as a presenting feature); (2) extrapulmonary, intrathoracic symptoms and signs—Horner’s syndrome, vocal cord paralysis, superior vena caval obstruction, dysphagia; (3) extrathoracic, metastatic manifestations—30% of patients present with symptoms due to distant metastases, the most common sites being bones, liver, adrenal glands, brain and spinal cord, lymph nodes, and skin; and (4) paramalignant syndromes—syndrome of inappropriate secretion of antidiuretic hormone, ectopic ACTH syndrome, hypercalcaemia, neuromyopathies, finger clubbing, and hypertrophic pulmonary osteoarthropathy.

Incidental findings and screening—about 5% of lung cancers are found by chance on a chest radiograph performed for reason other than suspicion of cancer, and these tend to have a better prognosis. Screening of high-risk groups for lung cancer with low-dose spiral CT is attracting interest and randomized trials are recruiting, but data as to whether mortality is reduced will not be available for at least 2 years.

Clinical staging—accurate clinical staging is paramount for treatment decisions, especially for NSCLC, which may be resectable. Following a chest radiograph, a CT of the thorax and upper abdomen should be performed. Biopsy of the primary tumour (via a bronchoscope for centrally situated lesions or by percutaneous image-guided needle, depending on best access) or of a metastasis is required, the latter providing a diagnosis and staging information at the same time. PET scanning, which depends on the uptake of a glucose analogue (fluorodeoxyglucose, FDG) by active tumour and its metastases, is recommended as the final staging test in those patients where resection or another curative treatment is contemplated.

Prognosis and management—(1) NSCLC— ‘curative’ treatment by surgical resection can be applied to 5 to 10% of all cases, of whom about 25% survive at 5 years. Radical radiotherapy cures very few with locally advanced disease, although better results are claimed with the addition of chemotherapy. In patients with advanced NSCLC and good performance status, survival at 1 year is 15 to 20% with supportive care, with chemotherapy adding about 5 months to the untreated median survival with an improvement in quality of life. (2) Small-cell tumours—life expectancy of those with untreated disease is about 3.5 months for limited disease and 6 weeks for extensive disease. Chemotherapy remains the cornerstone of treatment: modern regimens would be expected to achieve a complete response rate (i.e. disappearance of all measurable disease) in 40 to 50% of cases and a partial response rate (>50% reduction in tumour bulk) in a further 40%. Patients achieving a complete response after chemotherapy should have prophylactic cranial irradiation.

Management of complications—some complications of lung cancer require specific measures to alleviate symptoms: (1) vocal cord paralysis may be helped by injection of Teflon into the affected cord; (2) obstruction of the upper airway causing stridor, or of the lower major airways, is usually treated initially with radiotherapy; (3) malignant pleural effusion is treated with talc pleurodesis; (4) dexamethasone may control the symptoms of brain metastasis and, if so, this should be consolidated with radiotherapy.

The multidisciplinary team—the importance of the combined support to the patient and the family given by the family doctor, palliative care medical and nursing staff, and hospice organizations, and the hospital team cannot be overemphasized.