Tumours of the pancreas and hepatobiliary system; the spleen

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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 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, e.g. 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, non-malignant 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 rare 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

This is usually an adenocarcinoma arising from cells lining the ducts. About 80% arise in the head (the largest part) and 20% 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 (see 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
Direct spread may involve the common bile duct CB where it traverses the pancreas, the duodenum and the portal vein PV. Lymphatic spread may reach the paraduodenal peritoneum P and the nodes of the coeliac axis 1, the porta hepatis 2, the lesser and greater curves of the stomach 3, 4 and the hilum of the spleen 5. Spread may also occur via the bloodstream to the liver, lungs, etc.

Pancreatic cancer presents at a mean age of 65 and is rare under 50. 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 UK, 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).

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’s law, see Ch. 18, p. 259). 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. 258. 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 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.

CT 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 CT scans, ideally before 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 employed and the patient saved a fruitless attempt at resection.

Endoscopic ultrasound (EUS) and needle aspiration cytology

Where ultrasound and/or CT indicate a pancreatic head carcinoma may be resectable, endoscopic ultrasound 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. Endoscopic ultrasound 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.

Magnetic resonance cholangio-pancreatography (MRCP)

In biliary obstruction, MRCP produces images similar to ERCP in diagnostic usefulness but is particularly useful for confirming choledocholithiasis (bile duct stones) or for obstructive lesions of the bile duct itself such as cholangiocarcinoma or primary sclerosing cholangitis.

Endoscopic retrograde cholangio-pancreatography (ERCP) and therapeutic intervention

ERCP is now largely employed for therapeutic intervention. For obstructive jaundice due to stone, ERCP is the main mechanism for removing duct stones. For inoperable carcinoma of the pancreatic head, placing a tubular stent across the obstruction allows palliation of jaundice by draining the biliary tree. Plastic stents eventually become encrusted and occluded so wider bore expanding metallic stents are more often employed.

Lesions in the body and tail of the pancreas

When pancreatic cancer is suspected in a non-jaundiced patient, abdominal CT can confirm the diagnosis more reliably than ultrasound, although small tumours may be missed (see Fig. 24.2a and b). CT scanning also indicates retroperitoneal and portal vein invasion; it shows metastases in liver and lymph nodes and CT-guided needle biopsy can obtain histopathology specimens, all of which can determine resectability. CT scanning can understage the disease, chiefly because it does not detect small-volume hepatic and peritoneal deposits.

Case History

Fig. 24.2 Carcinoma of the head of the pancreas
(a) CT scan showing enlargement of the head of the pancreas P most suspicious of carcinoma. The dark circular lesion within the tail of the pancreas is a secondary cyst or pseudocyst C. (b)

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