Tumours of the Pancreas and Hepatobiliary System; the Spleen

Introduction

More than 90% of pancreatic cancers are adenocarcinomas derived from exocrine ductal cells. These have the worst survival of all gastrointestinal (GI) malignancies, with only about 12% surviving 1 year and 2% surviving 5 years. Much less commonly, neoplasia arises from exocrine acinar (secretory) cells (2%) or from endocrine islet cells (8%). Most endocrine tumours present with excess hormone secretion, for example, insulin, glucagon or gastrin. Around 90% of insulinomas are benign but most others are malignant, although survival is often prolonged.

Ductal adenocarcinoma typically presents late, with intractable abdominal pain, weight loss and obstructive jaundice caused by common bile duct compression, also a frequent presentation of the uncommon periampullary carcinomas . These include biliary cholangiocarcinomas and adenocarcinomas of the ampulla of Vater and duodenum.

Primary sclerosing cholangitis (PSC) is a rare, nonmalignant liver disease involving inflammatory fibrosis of bile ducts. It presents similarly to pancreatic cancer and is therefore included in this chapter. The uncommon carcinoma of gall bladder often presents with cholecystitis symptoms, with jaundice developing later.

Primary liver tumours are infrequent in developed countries but common in some developing countries, where hepatitis B and C are the main predisposing factors. Secondary liver tumours are common everywhere from haematogenous spread of many types of cancer. Surgical disorders of the spleen are covered at the end of this chapter.

Carcinoma of the Pancreas

Pathology

This is usually an adenocarcinoma arising from cells lining the ducts. About 60% to 70% arise in the head (the largest part) and 30% to 40% in the body or tail. Cancers often form a well-differentiated ductular pattern but despite this, it is a highly malignant tumour. It metastasises early to lymph nodes, to peritoneum, and to liver via the portal vein ( Fig. 24.1 ). At presentation, less than 20% are resectable and the overall prognosis is dire.

Fig. 24.1, Spread of Carcinoma of the Pancreas.

Pancreatic cancer presents at a mean age of 65 years and is rare under 50 years. The incidence is similar in males and females, and in the Western world, ranks equal third with oesophageal cancer among GI cancers, after large bowel and stomach. In absolute numbers, it is uncommon, being responsible for about 7000 deaths each year in the United Kingdom, although numbers in developed countries continue to rise. Risk factors include cigarette smoking (2–3 times the risk and presenting 15 years earlier), chronic pancreatitis (18 times risk, increasing to over 50 times in hereditary pancreatitis), obesity/type II diabetes (twice the risk), and positive family history.

Clinical Features of Ductal Pancreatic Carcinoma

There are no useful screening tests and so pancreatic cancer nearly always presents with symptoms and signs. The main features are substantial weight loss (80%), abdominal pain (60%) and obstructive jaundice (50%). Ascites and an abdominal mass are uncommon ( Box 24.1 ).

BOX 24.1

Presenting Features Of Pancreatic Carcinoma

Common Presenting Features

Substantial weight loss (about 80% of cases)
Abdominal pain (about 60%)
Obstructive jaundice, often without pain (about 50%)

Less Common Presenting Features

Acute pancreatitis (rare)
Diabetes mellitus (preceding or following diagnosis)
Gastric outlet obstruction (because of external compression)
Thrombophlebitis migrans (recurrent superficial venous thromboses)
Pancreatic steatorrhoea (because of pancreatic duct obstruction)

Pain and Other Abdominal Symptoms and Signs

The pain of advanced pancreatic carcinoma is severe and continuous and typically described as ‘deep’ and ‘gnawing’; it may drive patients to suicide. It is often nocturnal and poorly relieved by analgesics but sometimes alleviated by leaning forwards from sitting (‘the pancreatic position’). Severe pain usually represents locally advanced disease, with extrapancreatic invasion into retroperitoneal nerves around the coeliac axis. There are often ill-defined dyspeptic symptoms , such as anorexia, nausea or sporadic vomiting and usually profound weight loss .

Obstructive Jaundice

Jaundice, often without pain early on, develops over several weeks, and is associated with pale stools and dark urine. These clinical features are dramatic and never ignored. The jaundice is caused by common bile duct compression in its course through the pancreatic head. As a result, the proximal bile duct dilates and the gall bladder may become palpable ( Courvoisier law , see Ch. 18 , p. 285). Bile duct obstruction may also be caused by metastases in porta hepatis lymph nodes. Liver metastases alone rarely cause jaundice.

Note that pancreatic cancer and other obstructing biliary tumours typically produce a painless and progressive jaundice. In contrast, that of gallstone disease is less intense and fluctuates in intensity, and there is usually typical biliary pain.

Approach to Investigation of Suspected Pancreatic Carcinoma ( Box 24.2 )

A patient with obstructive jaundice should be investigated as described in Chapter 18 , p. 286. If pancreatic cancer is likely, optimum management is via a streamlined diagnostic pathway carried out in a specialised, high-volume pancreatic centre.

BOX 24.2

Investigation of Suspected Pancreatic Carcinoma

If patient jaundiced—suspect diagnosis from age, typical history, signs, liver function tests.
If patient not jaundiced—suspect diagnosis on abnormal ultrasound or computed tomography (CT, differential diagnosis is often pancreatitis).
- Primary imaging —usually CT scan
- Confirm histology —CT-guided biopsy, endoscopic ultrasound-guided needle aspiration cytology
- Assess primary tumour in detail —site, size, local invasion especially of blood vessels using ultrasound, high-definition CT
- Assess metastatic spread —liver, nodes, peritoneum using CT, laparoscopy, ± laparoscopic ultrasound

When investigations are complete, the multidisciplinary team considers whether curative treatment is feasible and how to plan and implement it, or if not appropriate, what palliative treatment is needed.

Computed Tomography and Ultrasound Imaging

Ultrasound seeks masses in pancreas and liver, dilated bile ducts and stones in the gall bladder (abdominal ultrasound is unreliable for common bile duct stones). Additional detail about a mass comes from high-resolution computed tomography (CT) scans, ideally before endoscopic retrograde cholangiopancreatography (ERCP) to ensure an artefact-free field. CT can show tumour extent and the presence and volume of liver metastases. It can demonstrate vascular invasion of superior mesenteric and portal veins, and superior mesenteric artery and coeliac axis, any of which lessen the feasibility of surgical resection. The extent of primary and/or metastatic disease on imaging may indicate the tumour is inoperable (i.e., not resectable with intent to cure). Palliation can then be used and the patient saved a fruitless attempt at resection.

Endoscopic Ultrasound and Needle Aspiration Cytology

Where ultrasound and/or CT indicate a pancreatic head carcinoma may be resectable, endoscopic ultrasound (EUS) can give added detail. In this, an ultrasound probe is positioned in the second part of the duodenum via a gastroscope. This allows precise examination of the pancreatic head and associated vessels, as well as duodenum and ampullary region. Ultrasound-guided needle aspiration sampling of suspicious lesions can be performed via the gastric lumen for cytology, either before surgery or to guide oncological management. EUS is the gold standard for assessing tumour size, site and vascular involvement and thus potential operability. However, its accuracy is severely impaired if a stent has already been placed to relieve jaundice.

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