Lung cancer

ETIOLOGY• Cigarette smoking• Pollutants• Family History• Recurring inflammations of the Lung• Radiation Therapy• Diet

PATHOPHYSIOLOGY• Lung cancers can arise from a single transformed epithelial cell in the

tracheobronchial airways. • A carcinogen binds to cell’s DNA and damages it. • This damage results in cellular changes, abnormal cell growth, and

eventually a malignant cell growth. • As the damaged DNA is passed on to daughter cells, the DNA

undergoes further changes and become unstable. • With the accumulation of genetic changes, the pulmonary epithelium

undergoes malignant transformation from normal epithelium to eventual invasive carcinoma.

TYPES OF LUNG CANCER• non-small cell lung cancer (NSCLC) • small cell lung cancer (SCLC).

• NSCLC is further classified into • squamous cell carcinoma• adenocarcinoma• large cell carcinoma.

• Squamous cell carcinoma occurs most frequently in the central zone of the lung whereas adenocarcinoma tumors are peripheral in origin, arising from the alveolar surface epithelium or bronchial mucosal glands. • Large cell carcinoma composes only 15% of all lung cancers and

appears to be decreasing in incidence because of improved diagnostic techniques.

The second major type of lung cancer is SCLC, in which there are also several histologic groupings: • pure small cell• mixed small cell • combined small cell.

• SCLC is usually more aggressive than NSCLC and presents as a central lesion with hilar and mediastinal invasion along with regional adenopathy. • Distant metastasis at presentation is common in patients with SCLC. • The most common sites of metastasis of lung cancer are the bones,

liver, adrenal glands, pericardium, brain, and spinal cord.

SIGNS AND SYMPTOMS• Neoplastic Local Growth• Cough• Dyspnea• Hemoptysis• Pain

Regional Growth• Dysphagia due to esophageal compression• Dyspnea due to phrenic nerve paralysis with an elevated hemidiaphragm• Hoarseness due to recurrent laryngeal nerve paralysis• Horner's syndrome because of sympathetic nerve paralysis leading to

Horner's syndrome (ptosis, miosis, anhidrosis, and enophthalmos).• Hypoxia• The superior vena cava can become obstructed and the heart and

pericardium can become involved. Lymphatic obstruction and spread can lead to dyspnea, hypoxia, and pleural effusions.

DIAGNOSIS• History and physical examination• Chest X- ray• CT scan• MRI scan• Positron emission tomography• Sputum cytology• Biopsy• Mediastinoscopy

MANAGEMENT• Surgery• Pneumonectomy• Lobectomy• Radiotherapy • Chemotherapy

PNEUMONECTOMY• The removal of the right lung is more dangerous than the removal of

left lung because the right lung has a larger vascular bed and its removal imposes a greater physiologic burden. • A posterolateral or anterolateral thoracotomy incision is made,

sometimes with the resection of the rib. • The pulmonary artery and the pulmonary veins are ligated and

served. The main bronchus is divided and the lung is removed. • The bronchial stump is stapled and usually no drains are used because

the accumulation of fluid in the empty hemithorax prevents mediastinal shift.

LOBECTOMY

• When the pathology is limited to one area of the lung, a lobectomy (removal of a lobe of lung) is performed. • The surgen makes a thoracotomy incision; its location depends on the lobe

to be resect. • When the pleural space is entered, the involved lung collapses and the

lobar vessels and the bronchus are ligated and divided. • After the lobe is removed, the remaining lobes of the lung are

reexpanded. • Usually two chest tube drains are inserted for drainage.

POST OPERATIVE MANAGEMENTPOSITION• Following pneumonectomy, a patient is usually turned every hour

from the back to the operative side and should not be completely turned to the unoperated side. • This allows the fluid left in the space to consolidate and prevents the

heart from shifting to the operated side (mediastinal shift).

• The patient with lobectomy may be shifted to either side and a patient with segmental resection usually is not turned onto the operative side unless the surgeon prescribes this position. • When the patient is conscious and the vital signs are stable, the head

end may be elevated to 30 to 45 degree.