Pancreatic cancer
Pancreatic adenocarcinoma is a malignancy with one of the highest mortality rates. It’s aggressive, causes no early symptoms, and is difficult to treat. It mostly affects elderly men.
About 85% of cases are irresectable at the time of diagnosis due to being metastatic or locally advanced.
Etiology
Pathology
Pancreatic adenocarcinoma accounts for almost all malignant exocrine pancreatic cancer (the remaining being acinar adenocarcinoma and mucinous cystadenocarcinoma). Adenocarcinomas originate from epithelial cells of the pancreatic tubules.
60% of cases are located in the head of the pancreas, with the remaining 40% being spread evenly throughout the body and tail.
Clinical features
Pancreatic cancer generally causes symptoms late, which contributes to the poor prognosis. Tumours in the pancreatic head cause symptoms earlier than tumours in the body or tail.
When symptoms do occur, jaundice, weight loss, anorexia, abdominal pain, vomiting, and constitutional symptoms may occur. Delayed gastric emptying occurs in up to 60% of people with pancreatic cancer and may contribute to the symptoms of anorexia and vomiting. Obstruction of the biliary tract is what leads to jaundice.
Invasion of nearby structures can cause chronic abdominal pain.
Courvoisier sign may be present. It refers to an enlarged, nontender gallbladder with painless jaundice. This contrasts with cholelithiasis, in which the gallbladder is tender.
Trousseau syndrome may also be present. It refers to a migratory, superficial thrombophlebitis.
Diagnosis and evaluation
Abdominal ultrasound is often the first investigation used in patients presenting with jaundice or epigastric pain. US is highly sensitive for pancreatic masses, and will show an echopoor lesion.
Contrast CT or MRI shows the mass and whether it’s resectable or not. Pancreatic cancer is hypodense on CT. It will also show any distant metastases.
The tumour marker CA 19-9 may be elevated; if it is, it may be used for follow-up. Liver enzymes may be elevated if cholestasis has occurred.
The diagnosis requires histological confirmation, which is acquired by biopsy in most cases. However, if the suspicion is high and the mass appears to be resectable, the patient may skip biopsy and proceeds directly to surgery, where the diagnosis is made by intraoperative frozen sections.
Treatment
Even with curative treatment, the survival rate of pancreatic cancer is poor. The 5-year survival after radical surgery + adjuvant oncological therapy is only 15 – 40%. The median survival is only 18 months.
Curative modalities
There are two options for surgical treatment of pancreatic head tumours, conventional pancreaticoduodenctomy (Whipple procedure), and pylorus-preserving pancreaticoduodenectomy. Both should be combined with regional lymphadenectomy.
For resectable tumours in the body or tail of the pancreas, an extended distal pancreatectomy is performed, usually with splenectomy.
Adjuvant chemotherapy is frequently used, usually with gemcitabine or 5-FU, combined with erlotinib.
Palliative surgery for pancreatic and periampullary tumours
Many cases of pancreatic and periampullary cancer are irresectable and therefore incurable. Palliative surgery is therefore common.
Palliative surgery may be indicated for jaundice or gastric outlet obstruction in people with irresectable pancreatic cancer. These are usually managed with the placement of stents into the obstructed biliary tree or obstructed duodenum with ERCP. In case stent placement is impossible or insufficient, a bypass operation may be necessary.
Palliative double bypass operation involves hepaticojejunostomy and gastrojejunostomy, i.e., diverting biliary flow to the jejunum rather than the duodenum, and diverting food passage to the jejunum as well.
Non-surgical palliative treatment
Pancreatic cancer pain usually requires opioid analgesics. Because the tumour may be close to the coeliac plexus, drugs effective against neuropathic pain may be used as adjuvants.
A permanent coeliac ganglion block (coeliac plexus neurolysis) can be used for pain management in case pharmacological therapy is insufficient. This involves radiographically guided puncture of the coeliac ganglion, followed by installation of ethanol, which destroys the nerve tissue permanently. Injection of a local anaesthetic instead produces temporary pain relief (and is mostly used for chronic pancreatitis).
Chemotherapy (with gemcitabine and erlotinib) may also be used for palliative therapy.
Prognosis
Pancreatic adenocarcinoma is very aggressive. Metastases are often present upon diagnosis. It frequently invades local structures and can even invade the portal vein itself. If the tumor invades other structures locally is it frequently considered inoperable. The 5-year survival rate is less than 5%.