Lung cancer

1. Lung cancer

2. Definition: • The term lung canceris used for tumors arising from the respiratory epithelium (bronchi, bronchioles, and alveoli). • Bronchial carcinoma accounts for 95% of all primary tumours of the lung. • Alveolar cell carcinoma accounts for 2% of lung tumours, and other less malignant or benign tumours account for the remaining 3%.

3. Bronchial carcinoma • This is the most common malignant tumour in the West and is the third most common cause of death in the UK after heart disease and pneumonia. • Male-to-female ratio of 3 : 1. Although the mortality rate from this disease has started to decrease in men, it continues to rise in women, and now causes more deaths from malignant disease in women than any other tumour.

4. Aetiological factors: • cigarette smoking, passive smoking (the frequent inhalation of other people's smoke by non-smokers) increases the risk of bronchial carcinoma by a factor of 1.5. • Occupational factors include exposure to asbestos, and an association is also claimed for workers in contact with arsenic,chromium, iron oxide, petroleum products and oils, coal tar, products of coal combustion, and radiation. • Tumours associated with occupational factors are mostly adenocarcinomas and appear to be less related to cigarette smoking.

5. there is a higher incidence of bronchial carcinoma in urban compared with rural areas, even when allowance is made for cigarette smoking. Pathology: • Four major cell types make up 88% of all primary lung neoplasms according to the WHO classification. • These are : • squamous or epidermoid carcinoma • small cell (also called oat cell) carcinoma • adenocarcinoma (including bronchioloalveolar) • large cellcarcinoma.

6. The remainder include: • undifferentiated carcinomas • carcinoids • bronchial gland tumors (including adenoid cystic carcinomas and mucoepidermoid tumors) • Based on the characteristics of the disease and its response to treatment bronchial carcinoma may be divided into: • small-cell carcinoma . • non-small-cell carcinoma.

7. Small-cell carcinoma: • This tumour, often called oat-cell carcinoma, accounts for 20-30% of all lung cancers. • It arises from endocrine cells .These cells are members of the APUD system, which explains why many polypeptide hormones are secreted by these tumours. Some of these polypeptides act in an autocrine fashion: they feed back on the cells and cause cell growth. • The tumour is rapidly growing ,highly malignant and spreads early so,it is almost always inoperable at presentation. • It responds to chemotherapy but the prognosis remains poor.

8. Non-small-cell carcinoma: • Squamous or epidermoid carcinoma: • It is the commonest type, accounting for approximately 40% of all carcinomas. • Most present as obstructive lesions of the bronchus leading to infection. • It occasionally cavitates (10%) at presentation. • The cells are usually well differentiated but occasionally anaplastic. • Local spread is common but widespread metastases occur relatively late.

9. Adenocarcinoma : • Arises from mucous cells in the bronchial epithelium. • Invasion of the pleura and the mediastinal lymph nodes is common, as are metastases to the brain and bones. • It accounts for approximately 10% of all bronchial carcinomas. • It is the most common bronchial carcinoma associated with asbestos and is proportionally more common in non-smokers, in women, andin the elderly. • Large cell carcinomas: • Are less-differentiated forms of squamous cell and adenocarcinomas. • These account for about 25% of all lung cancers and metastasize early.

10. Bronchoalveolar cell carcinoma (also termed bronchiolar carcinoma): • accounts for only 1-2% of lung tumours and occurs either as a peripheral solitary nodule or as diffuse nodular lesions of multicentric origin. • Occasionally this tumour is associated with expectoration of very large volumes of mucoid sputum.

11. Clinical features : Symptom : • Chest pain and discomfort are often described as fullness and pressure in the chest. • The pain may be pleuritic owing to invasion of the pleura or ribs. signs : • Often there are no abnormal physical signs. • Enlarged supraclavicular lymph nodes may be present. • There may be signs of a pleural effusion or of lobar collapse. • Signs of an unresolved pneumonia or of associated underlying disease (e.g. diffuse pulmonary fibrosis in asbestosis) may be present.

12. The frequency of the common presenting symptoms of bronchial carcinoma .

13. Direct spread : • The tumour may directly involve the pleura and ribs. • Carcinoma in the apex of the lung can erode the ribs and involve the lower part of the brachial plexus (C8, T1 and T2), causing severe pain in the shoulder and down the inner surface of the arm (Pancoast's tumour). • The sympathetic ganglion can also be involved, producing Horner's syndrome. • Hilar tumours may involve the recurrent laryngeal nerve, causing unilateral vocal cord paresis with hoarseness and a bovine cough.

14. Bronchial carcinoma can also directly invade the phrenic nerve, causing paralysis of the ipsilateral hemidiaphragm. It can involve the oesophagus, producing progressive dysphagia, and the pericardium, producing pericardial effusion and malignant dysrhythmias. • Superior vena caval obstruction causes early morning headache, facial congestion and oedema involving the upper limbs; the jugular veins are distended, as are the veins on the chest that form a collateral circulation with veins arising from the abdomen.

15. Metastatic complications: • Bony metastases are common, giving rise to severe pain and pathological fractures. • There is frequent involvement of the liver. • Secondary deposits in the brain present as a change in personality, epilepsy or as a focal neurological lesion. • Spinal cord compression is not uncommon and requires urgent treatment . • Secondary deposits in the adrenal gland are a very frequent post-mortem finding but are often asymptomatic. .

16. Non-metastatic extrapulmonary manifestations; Although approximately 10% of small-cell tumours produce ectopic hormones at some stage, clinical extrapulmonary manifestations are relatively rare apart from finger clubbing. Hypertrophic pulmonary osteoarthropathy (HPOA) : • occurs in approximately 3% of all bronchial carcinomas, particularly squamous-cell carcinomas and adenocarcinomas. • Symptoms include joint stiffness and severe pain in the wrists and ankles, sometimes associated with gynaecomastia. • X-rays show a characteristic proliferative periostitis at the distal ends of long bones, which have an onion-skin appearance. • HPOA is invariably associated with clubbing of the fingers. • It may regress after resection of the lung tumour.

17. Investigations : Chest X-ray • Asymptomatic tumours may be seen on chest X-ray if they are more than 1 cm in diameter. • Lateral views are useful to assess the hilum and masses behind the heart. • Although investigation of isolated haemoptysis with chest X-ray is often negative, a normal chest X-ray should not stop further investigation, especially in smokers over the age of 40y . • About 70% of all primary lung cancers present with a mass, including all small-cell lung cancers and most squamous cell carcinomas. • Adenocarcinoma occurs more often in the periphery than the other cell types.

18. Carcinomas causing partial obstruction of a bronchus interrupt the mucociliary escalator, and bacteria are retained within the affected lobe. This gives rise to the so-called secondary pneumonia that is commonly seen on the chest X-ray. • Bronchial carcinoma can also appear as round shadows on a chest X-ray , characteristically the edge of the tumour has a fluffy or spiked appearance, though sometimes it may be entirely smooth with cavitation. • The hilar lymph nodes on the side of the tumour are frequently involved. • Bronchial carcinoma is also a common cause of large pleural effusions.

19. Carcinoma can spread through the lymphatic channels of the lung to give rise to lymphangitis carcinomatosa; in bronchial carcinoma this is usually unilateral and associated with striking dyspnoea. The chest X-ray shows streaky shadowing throughout the lung.

22. Computed tomography CT: • It is useful for identifying disease in the mediastinum, such as enlarged lymph nodes or local spread of the tumour, and for identifying secondary spread of carcinoma to the opposite lung by detecting masses too small to be seen on the chest X-ray. • CT scanning should include the liver, adrenal glands and the brain since these are common sites for metastases.

23. Fibreopticbronchoscopy: • This technique is used to define the bronchial anatomy and to obtain biopsy and cytological specimens. • If the carcinoma involves the first 2 cm of either main bronchus, the tumour is inoperable as there would be insufficient resection margins for pneumonectomy. • Widening and loss of the sharp angle of the carina indicates the presence of enlarged mediastinal lymph nodes, either malignant or reactive. These can be biopsied by passage of a needle through the bronchial wall. • Vocal cord paresis indicates involvement of the recurrent laryngeal nerve and inoperability.

24. Percutaneous aspiration and biopsy: • Peripheral lung lesions cannot be seen by fibreopticbronchoscopy and samples may be obtained by direct aspiration or biopsy through the chest wall under appropriate X-ray or CT screening. • Fine-needle aspiration samples can be obtained from 75% of peripheral lesions that could not be biopsied transbronchially. Although useful if positive, negative FNA is not very helpful. • Biopsies obtained with Trucut needles are usually diagnostic.

25. Other investigations • Full blood count for the detection of anaemia. • biochemistry for liver involvement. • hypercalcaemia and hyponatraemia. • Bone scane for detection of bony metastases.

26. Treatment : • Treatment of lung cancer involves several different modalities and is best planned by a multidisciplinary team. • Treatment decisions need to reflect the poor overall survival rates: only 20% of patients are alive 1 year after diagnosis and only 6-8% after 5 years . Patients are staged according to the TNM classification for non-small-cell cancer but small-cell cancer is treated according to whether it is limited or extensive .

27. Surgical treatment: • Preoperative assessment includes exclusion of metastatic disease by blood tests and imaging. • Lung function tests, including walking oximetry, are used to predict postoperative potential. 1- Curative All operable and resectable cases . 2-Palliative a) Infection+haemoptysis b)Osteoarthropathy c)Pain d)Debulking of the tumour size

28. Non surgical lines of therapy could be used in Non-small-cell carcinoma: • Radiotherapy. • Radiotherapy+chemotherapy • Laser therapy, endobronchial irradiation and tracheobronchial stents

29. Secondary tumours: • Metastases in the lung are very common and usually present as round shadows (1.5-3.0 cm diameter). They may be detected on chest X-ray in patients already diagnosed as having carcinoma. • Typical sites for the primary tumour include the kidney, prostate, breast, bone, gastrointestinal tract, cervix and ovary. • Metastases nearly always develop in the parenchyma and are often relatively asymptomatic even when the chest X-ray shows extensive pulmonary metastases. • Rarely metastases may develop in the bronchi, when they may present with haemoptysis.

30. Carcinoma, particularly of the stomach, pancreas and breast, can involve mediastinal glands and spread along the lymphatics of both lungs (lymphangitis carcinomatosa), leading to progressive and severe breathlessness. On the chest X-ray, bilateral lymphadenopathy is seen together with streaky basal shadowing fanning out over both lung fields. • Occasionally a pulmonary metastasis may be detected as a solitary round shadow on chest X-ray in an asymptomatic patient(e.g. renal cell carcinom).

31. The differential diagnosis of solitary round shadow on chest X-ray includes: • primary bronchial carcinoma • tuberculoma • benign tumour of the lung • hydatid cyst.

32. SCREENING FOR LUNG CANCER • Screening programme (yearly chest X-ray, 4-monthly sputum cytology) have been tried in high-risk groups but the success rate is minimal, underlining the need for prevention. • CT screening is currently being evaluated.

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