LUNG CANCER

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I. LUNG CANCER
II. CLINICAL MANIFESTATIONS OF LUNG CANCER

QUESTIONS TO CONSIDER AS LEARNING OBJECTIVES:

• This combustible plant is high in tar and nicotine, and its smoke contains more than 5,000 chemicals, some of which are known to be complete or incomplete carcinogens.
  
• These unfortunate victims of lung cancer were convinced by advertising and the media in the 1950's that cigarette smoking was "fashionable".
  
• Lung cancer is now the leading cause of cancer death in both men and women, killing about this many people each year in the U.S.A..
  
• These two types of lung cancer tend to be found centrally in the lung in association with large airways.
  
• This theory proposes invisible changes in the DNA of exposed cells which become "activated" by chemicals known as "promoters".
  
• Cellular genes subverted toward neoplasia have been referred to by this designation.
  
• Scar cancer is another name applied to this peripherally-occurring form of lung cancer.
  
• Production of hormones and hormone like substance was originally attributed only to this particular form of lung cancer. This property has since been shown to occur with other bronchogenic carcinomas.
  
• The first recognizable aberrations in cells as they progress toward invasive carcinoma are seen in this part of the cell.
  
• This staging system is used to select treatment and predict outcome for patients with lung cancer. P36

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I. LUNG CANCER

• The overwhelming majority of lung cancers arise from the epithelial lining of the airways (90 95%) and are referred to as bronchogenic carcinomas.
  
• The incidence of lung cancer in U.S. men and women has risen to near epidemic proportions in the past 40 years, with current age-adjusted death rates of 74/100,000 men and 25/100,000 women annually.
  
• Tobacco smoking is the principal cause of lung cancer.
  
  • The evidence supporting this statement is statistical, clinical and experimental.
  • The initiation and promotion theory for chemical carcinogenesis is especially applicable to the understanding of the pathogenesis if this disease.
    
• There are 4 main histologic types of lung cancer, some with predilections for arising in certain areas of the lung:
  
  • Squamous cell carcinoma- central
  • Adenocarcinoma- peripheral
  • Small cell undifferentiated carcinoma- central
  • Large cell undifferentiated carcinoma- both
  • The division between small cell and non-small cell carcinomas is important clinically.
    
• Lung cancers are discovered in the population through two screening mechanisms.
  
  • The chest x-ray
  • Examination of sputum cytology. The latter can only be performed if individuals have chronic sputum production (as in chronic bronchitis).
  • Fine needle aspiration (FNA) also aids in diagnosis.

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II. CLINICAL MANIFESTATIONS OF LUNG CANCER

• Lung cancers grow at a predictable and very slow rate. Most lung cancers have been around for many years before they are discovered. For example, the estimated cell doubling time for squamous cell carcinoma of the lung is 150 days.
  
• Lung cancers may appear to grow "explosively" based on sequential chest x-rays once tumor diameter reaches about 3 cms. There is a mathematical explanation for this seemingly rapid change in tumor diameter based on relatively constant tumor doubling times.
  
• Lung cancers are staged using the TNM system where T stands for tumor diameter, N stands for lymph node metastasis and M stands for the presence of metastatic disease.
  
• The median survival for all patients with lung cancer despite aggressive surgical and medical therapy, is 15 months with overall 5 year survival of 9%. The smaller the lesion at discovery, the better the chance of survival.
  
• Some lung cancers may secrete hormones or hormone-like substances that are responsible for so-called "paraneoplastic" syndromes. These syndromes may actually precede the discovery of the tumor by many months. Small cell undifferentiated carcinoma (aka "oat cell" carcinoma) is especially infamous for this trait.
  
• Patients with one lung cancer are at high risk for developing a second lung cancer, assuming they survive long enough.
  
• Smokers can revert their risk of lung cancer by ceasing to smoke. It takes about 10 years to "normalize" this risk.
  
• Other tumors can arise in the lung.
  
  • Mesenchymal tumors
  • Pancoast's tumor
  • Carcinoid tumors
    

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[ Anatomy, Embryology and Physiology of the Lung | Edema, Embolism, Infarction, and Pulmonary Hypertension | Lung Infections | Adult Respiratory Distress Syndrome (ARDS) and Chronic Interstitial Lung Disease | Airway Diseases COPD | Lung Disease Caused by Inhaled Dust | Lung Cancer ]

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[ CATS Home | About CATS | CATS Teaching Modules | UVM Department of Pathology | Other Pathology Sites | UVM College of Medicine | UVM ]

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Questions? Comments? Send a message to the CATS guru: jkessler@salus.uvm.edu