Despite a decreasing incidence in the United States, small-cell lung cancer (SCLC) remains a major clinical problem, with approximately 30,000 new cases each year. The diagnosis of SCLC is usually not difficult. The Veterans Administration Lung Study Group (VALSG) staging system is less accurate than the American Joint Committee of Cancer tumor-node-metastasis (TNM) system (7th edition) at predicting survival in SCLC, especially in lower stage disease. Surgery has not played a major part in the management of SCLC, but emerging data suggest that resection may have a role in earlier stage disease. While the frontline treatment of SCLC has not changed significantly in the past decade, newer agents that are currently being investigated provide hope for better treatment of relapsed/refractory disease for the future.
Carcinoma of an unknown primary site is a common clinical syndrome, accounting for approximately 3% of all oncologic diagnoses. Patients in this group are heterogeneous, having a wide variety of clinical presentations and pathologic findings. A patient should be considered to have carcinoma of an unknown primary site when a tumor is detected at one or more metastatic sites, and routine evaluation (see below) fails to define a primary tumor site.
Despite the existence of excellent screening and preventive strategies, colorectal carcinoma (CRC) remains a major public health problem in Western countries. The American Cancer Society (ACS) estimated that in 2009, 146,970 people will be diagnosed with CRC, and 49,920 will die of the disease. CRC is the third most common type of cancer in both sexes (after prostate and lung cancers in men and lung and breast cancers in women) and the second most common cause of cancer death in the United States.
Pancreatic cancer is the fifth leading cause of cancer death in the United States. In the year 2009, an estimated 42,470 new cases are expected to be diagnosed, and 35,240 deaths are expected to occur.
Gastric cancer is more common than esophageal cancer in Western countries but is less fatal. More than 21,130 new cases of gastric cancer will be diagnosed in the United States in the year 2009, with 10,620 deaths expected. Worldwide, gastric cancer represents approximately 930,000 new cases and accounts for more than 700,000 deaths. The incidence and mortality of gastric cancer have been declining in most developed countries, including the United States; the age-adjusted risk (world estimate) fell 5% from 1985 to 1990.