Radiation Oncology/Pancreas/Overview

Epidemiology

4th leading cause of cancer-related death in men and women (http://apps.nccd.cdc.gov/uscs/toptencancers.aspx)

Estimated 31,000 deaths in 2004. (12.3 per 100,000 population)

Incidence 10th for males, and females. Males: 13.1 per 100,000, Females: 10.2 per 100,000. http://apps.nccd.cdc.gov/uscs/toptencancers.aspx

Incidence stable over past 20 years but has increased 3-fold since 1920

Higher incidence in African Americans and males.

Incidence peaks in 7th and 8th decades. Very uncommon before age 40.

Risk factors are smoking, high fat diet, obesity.

60-80% of patients had diabetes diagnosed within the preceding 2 years.

Anatomy

• Divisions of the pancreas include the head, uncinate process, neck, body, tail
• Duct of Wirsung is pancreatic duct located in substance of pancreas and draining to common bile duct

• Anatomic Landmarks
  • Celiac axis originates at T11-12
  • SMA originates at L1 vertebral body (usually 1cm below celiac axis)

• Nodal drainage
  • Pancreatic head - ant/post pancreaticoduodenal nodes, hepatoduodenal ligament nodes (including porta hepatis), SMA nodes
  • Pancreatic body/tail - splenic artery nodes, celiac nodes, SMA nodes, paraaortics, inf pancreatic nodes

Pathology

• Adenocarcinoma
• Neuroendocrine 1-2%
• Cystic neoplasms (serous cystadenomas, mucinous cystic neoplasms) <10%
• Intraductal papillary mucinous tumors
• Solid pseudopapillary tumors
• Acinar cell
• Squamous cell
• Primary lymphoma of the pancreas 1%

Patient characteristics

• 80% have unresectable disease
• 52% are Stage IV
• 5-year overall survival is lowest of any cancer
• Survival with resection: 48% (1-year), 24% (2-year), 17% (3-year)
• Survival without resection: 23% (1-year), 9% (2-year), 6% (3-year)

Tumor markers

• CA 19-9 - has 70% sensitivity, 87% specificity when using a cutoff of 70 U/mL. Elevated in benign conditions as well, such as cholangitis. But the higher the CA 19-9, the more likely to have cancer. The pretreatment level is prognostic. A decreasing value after treatment with surgery, XRT, or chemo associated with better survival.

Prophylactic Hepatic Irradiation

• Tochigi, 2005 (Japan) (1994-2003) PMID 15995813 -- "Prophylactic hepatic irradiation following curative resection of pancreatic cancer." (Hishinuma S, J Hepatobiliary Pancreat Surg. 2005;12(3):235-42.)
  • Retrospective. 65 patients, 34 with prophylactic hepatic irradiation (PHI), 31 without. RT dose 19.8-22.0 Gy + CI 5-FU
  • Complications: 32/34 completed RT; 1 liver abscess, 1 death from hepatic failure without mets
  • Liver failure: better in PHI group (p=0.05); Survival: better in PHI group (p=0.0002)

• Hopkins, 1997 (1991-1995) PMID 9193189 -- "Pancreaticoduodenectomy for pancreatic adenocarcinoma: postoperative adjuvant chemoradiation improves survival. A prospective, single-institution experience." (Yeo CJ, Ann Surg. 1997 May;225(5):621-33; discussion 633-6.). See above. No benefit.

• RTOG 8801 (1988-89) PMID 1571912 -- "High-dose local irradiation plus prophylactic hepatic irradiation and chemotherapy for inoperable adenocarcinoma of the pancreas. A preliminary report of a multi-institutional trial (Radiation Therapy Oncology Group Protocol 8801)." (Komaki R, Cancer. 1992 Jun 1;69(11):2807-12.).
  • 79 pts w/ unresectable, inoperable, or recurrent T1-3 adenoCA of pancreas. Tx'd w/ 6120 cGy to pancreas + simultaneous 2340 cGy prophylactic hepatic irradiation. Pts received concurrent 5FU.
  • Hepatic metastases documented in 32%, local progression in 73%, abdominal spread in 27%
  • 2 grade 5 complications (1 hepatic failure), 9 grade 4 complications (mostly hematologic)
  • Conclusion: PHI may reduce frequency of hepatic metastases, but local progression and abdominal spread ultimately uncontrollable.

Other Resources

• ARRO Case - Borderline Resectable Pancreatic Cancer
• ARRO Contour - Borderline Resectable Pancreatic Cancer
• eContouring Webinar - GI malignancies with Karyn Goodman, M.D.