OverviewLung cancer is the leading cause of cancer-related death in the United States. An estimated 219,440 new cases (116,090 men; 103,350 women) of lung and bronchus cancer were diagnosed in 2009, and 159,390 deaths (88,900 men; 70,490 women) occurred from the disease.1 Only 15% of all lung cancer patients are alive 5 years or more after diagnosis

Neuroendocrine tumors account for approximately 20% of lung cancers; most (≈15%) are small cell lung cancer (SCLC). These NCCN Clinical Practice Guidelines in Oncology for SCLC focus on extensive-stage SCLC because it occurs more frequently than limited-stage disease. SCLC is highly sensitive to initial therapy; however, most patients eventually die of recurrent disease. In patients with extensive-stage disease, chemotherapy alone can palliate symptoms and prolong survival in most patients; however, long-term survival is rare. Most cases of SCLC are attributable to cigarette smoking; therefore, smoking cessation should be strongly promoted.

Most patients with non-small cell lung cancer (NSCLC) are diagnosed with advanced cancer. These guidelines only include information about stage IV NSCLC. Patients with widespread metastatic disease (stage IV) are candidates for systemic therapy, clinical trials, and/or palliative treatment. The goal is to identify patients with metastatic disease before initiating aggressive treatment, thus sparing these patients from unnecessary futile treatment. If metastatic disease is discovered during surgery, then extensive surgery is often aborted. Decisions about treatment should be based on multidisciplinary discussion.

Radiation necrosis in the brain commonly occurs in three distinct clinical scenarios, namely, radiation therapy for head and neck malignancy or intracranial extraaxial tumor, stereotactic radiation therapy (including radiosurgery) for brain metastasis, and radiation therapy for primary brain tumors. Knowledge of the radiation treatment plan, amount of brain tissue included in the radiation port, type of radiation, location of the primary malignancy, and amount of time elapsed since radiation therapy is extremely important in determining whether the imaging abnormality represents radiation necrosis or recurrent tumor. Conventional magnetic resonance (MR) imaging findings of these two entities overlap considerably, and even at histopathologic analysis, tumor mixed with radiation necrosis is a common finding. Advanced imaging modalities such as diffusion tensor imaging and perfusion MR imaging (with calculation of certain specific parameters such as apparent diffusion coefficient ratios, relative peak height, and percentage of signal recovery), MR spectroscopy, and positron emission tomography can be useful in differentiating between recurrent tumor and radiation necrosis. In everyday practice, the visual assessment of diffusion-weighted and perfusion images may also be helpful by favoring one diagnosis over the other, with restricted diffusion and an elevated relative cerebral blood volume being seen much more frequently in recurrent tumor than in radiation necrosis.

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