Page 664 - Textbook of Pathology, 6th Edition

648 African Americans and accounts for 5% of all cancer deaths
in that country. It is commoner in males than in females and
the incidence increases progressively after the age of 50 years.

ETIOLOGY. A significant increase in the incidence of
pancreatic cancer has been observed in the UK and US during
the last 50 years. Little is known about etiology of pancreatic
cancer. However, following factors have been implicated in
its etiology:
1. Smoking: Heavy cigarette smokers have higher incidence
than the non-smokers. However, it is not known whether
tobacco metabolites have a direct carcinogenic effect on the
pancreas or by some other unknown mechanism.
2. Diet and obesity: Diet with high total caloric value and
high consumption of animal proteins and fats is related to
higher incidence of pancreatic cancer. Obesity is a risk factor
for pancreatic cancer.
3. Chemical carcinogens: Individuals exposed to β-naph-
thylamine, benzidine and nitrosamines have higher incidence
of cancer of the pancreas.
4. Diabetes mellitus: Patients of long-standing diabetes Figure 21.49 Distribution of carcinoma of the pancreas (numbered
mellitus have a higher incidence. serially) and its major effects.
5. Chronic pancreatitis patients are at increased risk.
6. H. pylori infection has been reported to have association constitutes less than 1% of pancreatic cancers. The
with pancreatic cancer. following histologic patterns of pancreatic carcinoma are
7. Genetic factors have been ound to have association with seen:
pancreatic cancer e.g. its occurrence in first-degree relatives 1. Well-differentiated adenocarcinoma, both mucinous and
in 10% cases, occurrence in certain hereditary syndromes non-mucin secreting type, is the most common pattern.
(Lynch, FPC, HNPCC). Perineural invasion is commonly present and is diagnostic
SECTION III
However, excessive consumption of alcohol or coffee, and of malignancy.
cholelithiasis are not risk factors for pancreatic cancer. A 2. Adenoacanthoma consisting of glandular carcinoma and
combination of mutations in K-RAS gene and CDKN2A gene benign squamous elements is seen in a proportion of cases.
have been found in almost all cases of cancer of the pancreas. 3. Rarely, peculiar tumour giant cell formation is seen with
marked anaplasia, pleomorphism and numerous mitoses.
MORPHOLOGIC FEATURES. The most common loca- 4 Acinar cell carcinoma occurs rarely and reproduces the
tion of pancreatic cancer is the head of pancreas (70%), pattern of acini in normal pancreas.
followed in decreasing frequency, by the body and the
tail of pancreas (Fig. 21.49). CLINICAL FEATURES. Clinical symptoms depend upon
Grossly, carcinoma of the head of pancreas is generally the site of origin of the tumour. Generally, the following
small, homogeneous, poorly-defined, grey-white mass features are present:
Systemic Pathology
without any sharp demarcation between the tumour and 1. Obstructive jaundice. more often and early in the course
the surrounding pancreatic parenchyma. The tumour of of disease in cases with carcinoma head of the pancreas (80%),
the head extends into the ampulla of Vater, common bile and less often in cancer of the body and tail of the pancreas.
duct and duodenum, producing obstructive biliary It is characterised by: dark urine, clay-like stools, pruritus,
symptoms and jaundice early in the course of illness. and very high serum alkaline phosphatase.
Carcinomas of the body and tail of the pancreas, on the 2. Other features. These include: abdominal pain, anorexia,
other hand, are fairly large and irregular masses and weight loss, cachexia, weakness and malaise, nausea and
frequently infiltrate the transverse colon, stomach, liver, vomiting, and migratory thrombophlebitis (Trousseau’s
spleen and regional lymph nodes. syndrome), GI bleeding and splenomegaly.
Microscopically, most pancreatic carcinomas arise from The prognosis of pancreatic cancer is dismal: median
the ductal epithelium which normally comprises less than survival is 6 months from the time of diagnosis. Approxi-
4% of total pancreatic cells, whereas carcinoma of the acini mately 10% patients survive 1 year and the 5-year survival
is poor 1 to 2%.

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