ESSENTIALS OF DIAGNOSIS
Abdominal protocol computed tomography (CT) with arterial and venous phases is generally the best initial modality for diagnosis and staging.
Endoscopic ultrasound (EUS) is superior to CT in diagnosing small tumors, and can be used to obtain pathologic confirmation of the diagnosis.
Fewer than 20% of tumors are resectable at the time of diagnosis.
Carbohydrate antigen 19-9 (CA 19-9) and carcinoembryonic antigen (CEA) have a low specificity and sensitivity, but can be followed for treatment response if initially elevated.
Pancreatic cancer is a challenging disease associated with an overall 5-year survival of 4–6%. It is the second most common gastrointestinal malignancy, and the fourth leading cause of cancer-related deaths in the United States. In 2012, the incidence was estimated as 43,920 new cases in the United States, while in 1996 there were 26,300 new cases.
The disease is more common in men than in women (1.3:1) and in certain ethnic and racial groups (eg, Blacks, Polynesians, and native New Zealanders). It is rare before the age of 40, but the incidence increases sharply after the seventh decade.
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A. Cancer statistics, 2012. CA Cancer J Clin
Pathogenesis & Risk Factors
Most pancreatic neoplasms arise from the three different types of the epithelial cells found in the pancreas. Acinar cells account for 80% of the volume of the gland but constitute 1% of exocrine tumors. Ductal cells constitute 10–15% of the volume but give rise to 90% of all tumors. Other malignant pancreatic tumors from the exocrine pancreas include intraductal papillary mucinous neoplasms with invasive carcinoma (2–3%), mucinous cystic neoplasms with invasive carcinoma (1%), solid pseudopapillary neoplasms (<1%), acinar cell carcinoma (<1%), and serous cystadenocarcinoma (<1%). Endocrine cells are 1–2% of volume and account for 1–2% of the tumors. These tumors are known as pancreatic neuroendocrine tumors (PNET) or islet cell tumors. Nonepithelial tumors are very rare.
Approximately 70% of ductal tumors are localized to the head of the pancreas, 5–10% to the body, and 10–15% to the tail. These tumors appear as scirrhous whitish irregular tumor with a desmoplastic reaction that can mimic chronic pancreatitis particularly at the time of surgical resection. The desmoplastic reaction can make it impossible to evaluate radiologically the response to preoperative treatment.
These tumors are often associated with pancreatic intraepithelial neoplasia (PanIN), which is metaplasia and proliferation of the ductal epithelium. PanIN is associated with varying degrees of dysplasia ranging from mild (PanIN-1), moderate (PanIN-2), to severe (PanIN-3), which was previously known as carcinoma in situ. In general, a surgeon will resect to remove invasive carcinoma and PanIN-3, but not PanIN-1 or PanIN-2.