Cystic tumours are quite rare lesions of the pancreas, representing 1% of malignant neoplasms of the pancreas. Histologically, they range from benign tumours of adenomatous appearance to cystadenocarcinomas. The tumours may have either mucous or serous fluidcontaining cysts; the former having a greater malignant propensity. Recognition and differentiation from benign cysts is important because surgical excision is associated with cure.
The typical presentation of a patient with adenocarcinoma of either the ampulla or the pancreas is a person with ‘painless jaundice’. There may also have been a period of anorexia with associated weight loss. The patient may report pale-colored stools, occasionally said to have silver streaks on their surface. In addition, the urine is dark and the skin yellow. On examination, an abdominal mass may be detected; however, more commonly the tumour will not be palpable. A distended gall bladder may be palpated under the right costal margin and this sign in a patient with painless obstructive jaundice is strongly suggestive of a malignant pancreatic cause (Courvoisier’s Law).In patients in whom the bile duct is not involved early in the disease, presentation may be due to early spread of the tumour and resulting pain in the epigastrium or mid-back. Pain is a poor prognostic factor in a patient with pancreatic cancer because it invariably signals spread of the disease.
Patients with pancreatic malignancy usually present with symptoms and signs of obstructive jaundice. Therefore, investigations are directed at the differential diagnosis of this condition. Ultrasound examination will demonstrate a dilated extrahepatic biliary system, often with dilated intrahepatic ducts and a distended gall bladder. Depending on its size, a mass may be seen in the head of the pancreas. With ampullary tumours a mass will not be detected but the pancreatic duct may be seen to be dilated. The most precise investigation, providing the most information, is endoscopic retrograde cholangiopancreatography (ERCP). This endoscopic procedure allows for direct visualisation of the ampulla, and after cannulation of the bile and pancreatic ducts, contrast may be injected into the ducts and X-rays taken to visualize any signs of obstruction. Cancer of the head of the pancreas shows a characteristic narrowing of both ducts on ERCP (the double duct sign). Biopsy of any visualised abnormality, or cytology from the structured areas, can provide histological confirmation of the diagnosis. Computed tomography (CT) scanning may demonstrate a mass in the pancreas, but often small masses may not readily be seen. For larger masses and when histological confirmation is needed prior to treatment, a percutaneous biopsy may be done under either CT scan or ultrasound guidance. Serum tumour markers have been used for the diagnosis of various abdominal neoplasms. The tumour associated antigen CA19-9 has been extensively investigated to assess its role in the diagnosis of pancreatic cancer. This antigen is certainly detected in the serum of patients with pancreatic cancer, and there appears to be a direct correlation between tumour size and level of CA19-9. However, its specificity is low as is its sensitivity for small tumours. Its main value currently is in the follow-up of patients with high values to assess response to treatment.
The only form of therapy that potentially may cure patients with cancer of the pancreas is surgical resection. For surgery to be effective early diagnosis is essential in order to detect lesions of relatively small size. Put another way, the best surgical results are achieved in patients with small tumours. In general, a diameter of 3 cm or less will be resectable and potentially give the best outcome. Due to their position, ampullary cancers tend to present earlier than cancers of the rest of the pancreas and, consequently, have the best outcome following surgery. In addition, surgical removal of cystic tumours is associated with an excellent outcome. Cancers of the body of the pancreas tend to present late and, in general, are not resectable. Similarly, most cancers of the head of the pancreas are not resectable for cure. Occasionally, however, they may become symptomatic early and can be resected with good results. Thus, despite the generally gloomy picture regarding the curative treatment of these cancers, it should be remembered that for certain tumours curative resection is possible and all attempts should be made to identify these patients and not place all patients in the incurable category.
For the majority of patients with cancer of the pancreas, treatment is directed at palliation. The most common presentation is that of obstructive jaundice, whichis associated with anorexia and pruritus. Treatment that aims to relieve the obstruction relieves the pruritus and also improves the patient’s well-being. The life expectancy of a patient with an inoperable cancer of the pancreas is approximately 10 months. Therefore, the aim of palliation is to do the least invasive procedure that will achieve drainage of the bile duct and relieve the obstructive jaundice. In the majority of patients excellent palliation is achieved by inserting an endoprosthesis (stent) through the obstruction using an endoscopic approach. The stent drains bile from the proximal bile duct into the duodenum and the jaundice is relieved. If the endoscopic approach is not successful a percutaneous route through the liver may be used to place the stent. However, in general, the morbidity and results of this approach are not as good as the endoscopic route. The advantage of the endoscopic and percutaneous treatment is the fact that it avoids the need for laparotomy, and the patient’s recovery is therefore rapid. It should be emphasised that this procedure should only be used in patients in whom pre-operative investigations have determined that the tumour is inoperable. Surgical bypass of the tumour to drain the biliary tract and relieve the jaundice is done in patients who have undergone laparotomy to assess resectability but in whom curative resection was not possible. Patients with inoperable cancers often inquire about the use of chemotherapy and radiotherapy, but these treatments have not been shown to be effective in the treatment of pancreatic cancer. It should be remembered that unless it can be shown that these forms of treatment can prolong survival they should not be used because there are significant side effects.