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Lung Cancer Knowledge Bites

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					Lung Cancer Knowledge Bites Epidemiology:  Most frequent cause of cancer death in U.S.  Most common cause of CA death in women  Second most common cause of CA death in men  14% of all CA diagnosis  28% of all CA death  Incidence continues to rise in women while falling in men because smoking cessation in women has lagged behind that of men Etiology:  Cigarette smoking  Asbestos, arsenic, chromium, nickel, organic chemicals  Iatrogenic radiation exposure  Second hand smoke Essentials of Diagnosis:  Cough, dyspnea, hemoptysis, anorexia or weight loss  Enlarging mass, infiltrate, atelectasis, cavitation, or pleural effusion on chest radiograph or CT scan  Cytologic or histologic findings diagnostic of primary lung CA in sputum, pleural fluid, or tissue Pathology:  Adenocarcinoma(ACA)- 45% of all lung CA  Derived from mucous-producing cells of the bronchial epithelium  Most are peripherally located  Tends to metastasize early  Bronchoalveolar- subgroup of ACA  More indolent than ACA  Highly differentiated and spreads along alveolar wall  Presents as solitary nodule, multiple nodules, or diffuse parenchymal infiltrates  Squamous cell- 30% of all lung CA  Most centrally located and tend to expand against the bronchus  Prone to central necrosis and cavitation  Tend to metastasize later than ACA  Small cell- 20% of all lung CA  Most centrally located  Very aggressive tendency to metastasize  Microscopically, cells appear as sheets or clusters of cells with dark nuclei and very little cytoplasm- giving an “oat-like appearance”(Oat-cell CA)

Clinical Course:  Depends on the type of primary CA, its metastases, systemic effects of CA and any coexisting paraneoplastic syndromes  10-25% of patients asymptomatic at time of diagnosis  Symptomatic lung CA often advanced and non-resectable  Initial symptoms include cough, weight loss, dyspnea, chest pain, and hemoptysis  Physical findings often absent  Central tumors may obstruct bronchi causing atelectasis and post-obstructive pneumonitis with typical physical findings  Lymphadenopathy, hepatomegaly and clubbing present in some patients  Infrequent findings include: superior vena cava syndrome, Horner’s syndrome, Pancoast’s syndrome, recurrent laryngeal nerve palsy with hoarseness, phrenic nerve palsy with hemidiaphragm paralysis and skin metastases  Paraneoplastic syndromes occur in 20% of lung CA patients  Syndrome of extrapulmonary organ dysfunction not related to effects of the primary or metastases  Common types:  Adenocarcinoma- nonbacterial verrucous(marantic) endocarditis  Small cell- Cushing’s syndrome, SIADH  Squamous cell- hypercalcemia  Large cell- gynecomastia Staging: TNM staging used  Primary tumor(T)  T0: no tumor  Tis: tumor in situ  T1: <3cm, surrounded by pleura, no invasion of lobar bronchus  T2: >3cm, or tumor that invades a main bronchus(>2cm distal to carina) or visceral pleura, or tumor that has associated atelectasis or obstructive pneumonitis involving less than the entire lung  T3: any size with extension into chest wall, diaphragm, mediastinal pleura, parietal pericardium, or tumor in main bronchus(<2cm from carina but not involving), or associated atelectasis/pneumonitis of entire lung  T4: any size with invasion of mediastinum, heart, great vessels, trachea, esophagus, vertebral body, carina, or with a malignant pleural or pericardial effusion or with ipsilateral satellite nodules  Regional lymph nodes(N)  N0: no metastases to regional lymph nodes  N1: metastases to nodes in peribronchial and/or ipsilateral hilar region  N2: metastases to ipsilateral mediastinal nodes and/or subcarinal nodes  N3: metastases to contralateral mediastinal nodes, contralateral hilar nodes , ipsilateralor or contralateral scalene or supraclavicular nodes  Distant metastases(M)  M0: no distant metastases  M1: distant metastases present

Treatment:  Main treatment options include surgery, chemotherapy and radiation therapy  Only 25% of patients with lung CA are candidates for surgery  Surgery not appropriate for patients with small cell CA  Contraindications for surgery include: extrathoracic mets, tumor involving trachea, carina, esophagus, pericardium, or proximal main stem bronchi(<2cm from carina), malignant pleural effusion, recurrent laryngeal nerve or phrenic nerve palsy, superior vena cava syndrome, spread to contralateral mediastinal lymph nodes, poor general health, impaired pulmonary function or extensive involvement of the chest wall  Patients with hypercapnia and significant pulmonary hypertension are not good candidates for surgery  Combination chemotherapy is the treatment of choice for small cell CA  Radiation therapy is often used to palliate symptoms of lung CA Prognosis:  Overall 5 yr. survival is 10-15%  Overall 5 yr. survival after “curative” resection of: squamous cell CA is 35-40%, adenocarcinoma and large cell is 25%  Patients with small cell CA rarely live past 5 yrs.


				
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posted:11/13/2009
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