Lung Cancer

Lung cancer is a malignant lung tumor that is characterized by uncontrolled cell growth in the tissues of the lung.  Two main types are small-cell lung carcinoma (SCLC) and non-small-cell lung carcinoma (NSCLC).

Lung cancer is the leading cause of cancer deaths worldwide in both men and women.  NSCLC accounts for approximately 85% of cases, with the remainder being SCLC.  An estimated 158,080 Americans died from lung cancer in 2016, which accounts for 27% of all cancer deaths.  

Cancer occurs following genetic damage to DNA after exposure to certain risk factors.  These chances affect the normal functions of a cell, and may lead to uninhibited cell proliferation, impaired cell death, and impaired DNA repair.  

Similar to other cancers, lung cancer is initiated by the activation of oncogenes or inactivation of tumor suppressor genes.  Carcinogens cause mutations in these genes which induce the development of cancer.

Undoubtedly, cigarette smoking is the leading cause of lung cancer.  Smoke contains at least 73 carcinogens which induce cellular changes leading to tumor growth.  Other risk factors include asbestos, air pollution, genetics, metals (cadmium, chromium, arsenic, beryllium, etc), ionizing radiation.

Signs and systems may include several different systems:

• Respiratory symptoms: cough (in 50-75% of patients), hemoptysis (25-50%), wheezing, dyspnea (25%)

• Systemic: weight loss, weakness, fever, clubbing of fingernails

• Mass effect on other structures: Chest pain, bone pain, superior vena cava obstruction, difficulty swallowing

Every patient with the above risk factors and signs/symptoms should undergo a more thorough history and physical exam.  The presence of these signs or symptoms typically indicate advanced disease and poor prognosis.  The following lab tests may aid in diagnosis: CBC, electrolytes, alkaline phosphatase (if elevated, suspect bony or liver metastases)

Chest x-ray is usually the initial imaging modality of choice in those with undifferentiated dyspnea.  There may be new, focal solid appearing lesions, pleural effisions, enlarged hilar or paratracheal nodes, pleural nodularity.

 Further imaging with chest CT may better characterize the lesion, with whole body PET CT considered if evaluating for metastatic disease or for resectable lesions in lower stages of disease. Formal diagnosis of NSCLC is made based upon the pathologic evaluation of cytologic or histopathologic specimens.  

For NSCLC, initial management is determined by the stage of disease, and for patients with early stage disease, surgical resection offers the best opportunity for long-term survival. In advanced disease, patients are managed palliatively with systemic therapy.  

SCLC is a disseminated disease in most patients at time of presentation and is very responsive to chemotherapy, and thus systemic chemotherapy is an integral part of initial treatment.  Surgery is not used except in those rare SCLC patients with solitary pulmonary nodule without distant metastases.