PANCREATIC CANCER

Pancreatic Cancer

Pancreatic Cancer

Background

Pancreatic cancer is the fourth leading cause of death among both men and women, comprising 6% of all cancer-related deaths. The incidence of pancreatic cancer has risen slowly over the years. The disease is notoriously difficult to diagnose in its early stages. At the time of diagnosis, 52% of all patients have distant disease and 26% have regional spread. The relative 1-year survival is only 24% and the overall 5-year survival rate for this disease is less than 5%.

Pancreatic cancer Gross section of an adenocarcinoma

Pancreatic cancer Gross section of an adenocarcinoma of the pancreas measuring 5 X 6 cm resected from the pancreatic body and tail. Although the tumor was considered to have been fully resected and had not spread to any nodes, the patient died of recurrent cancer within 1 year.

Pancreatic cancer. Gross section of an adenocarcinoma of the pancreas measuring 5 X 6 cm resected from the pancreatic body and tail. Although the tumor was considered to have been fully resected and had not spread to any nodes, the patient died of recurrent cancer within 1 year.

Pathophysiology

Pancreatic cancers can arise from both the exocrine and endocrine portions of the pancreas. Of pancreatic tumors, 95% develop from the exocrine portion of the pancreas, including the ductal epithelium, acinar cells, connective tissue, and lymphatic tissue. Approximately 75% of all pancreatic carcinomas occur within the head or neck of the pancreas, 15-20% occur in the body of the pancreas, and 5-10% occur in the tail.

Typically, pancreatic cancer first metastasizes to regional lymph nodes, then to the liver, and, less commonly, to the lungs. It can also directly invade surrounding visceral organs such as the duodenum, stomach, and colon or metastasize to any surface in the abdominal cavity via peritoneal spread. Ascites may result, and this has an ominous prognosis. Pancreatic cancer may spread to the skin as painful nodular metastases. Pancreatic cancer uncommonly metastasizes to bone. It is rare for pancreatic cancer to spread to the brain. It can, however, produce meningeal carcinomatosis.

The molecular genetics of pancreatic adenocarcinoma have been well studied.1,2,3 Of these tumors, 80-95% have mutations in the KRAS2 gene, and 85-98% have mutations, deletions, or hypermethylation in the CDKN2 gene. Of these cancers, 50% have mutations in p53 and about 55% have homozygous deletions or mutations of Smad4. Some of these mutations can also be found in high-risk precursors of pancreatic cancer. For example, in chronic pancreatitis, 30% of patients have detectable mutations in p16 and 10% have K-ras mutations.

Families with BRCA-2 mutations, which are associated with a high risk of breast cancer, also have an excess of pancreatic cancer.4 Assaying pancreatic juice for the genetic mutations associated with pancreatic adenocarcinoma is invasive but may be useful for the early diagnosis of the disease;5 this approach is problematic as genetic mutations in the pancreatic juice may be found associated with inflammatory pancreatic disease.

Certain precursor lesions have been associated with pancreatic tumors arising from the ductal epithelium of the ...