12. Pancreatic Carcinoma Flashcards
Why is pancreatic cancer such a complicated topic? What are we focusing in on?
Complex because the pancreas has so many different tissue types, all of which can give rise to neoplasms.
We’re focusing on Exocrine Neoplasms from duct and acinar cells – most from ductal cells
[Other types are neuroendocrine neoplasms (covered during Endocrine), Primitive and Mixed neoplasms (from stem cells) and Sarcomas from stromal cells (extremely rare).]
At the basic level, what do we mean when we say “pancreatic cancer”?
Unless otherwise specified, we mean ductal adenocarcinoma or one of its subtypes. These are the dominant types of pancreatic neoplasms (90% of pancreatic neoplasms are ductal adenocarcinomas).
What is this? Features?
Pancreatic ductal adenocarcinoma.
See a few ducts which look abnormal, lots of fibrous tissue. Desmoplastic neoplasms -> simulate growth of fibrous tissue -> Become hard masses.
These are 3 grades and 2 subtypes of ductal adenocarcinoma: what differentiates the 3 grades?
Grade 1: Can still recognize duct structures.
Grade 2: Moderate; hard to recognize ducts
Grade 3: Advanced; hard to idenfity ducts, poorly-differentiated neoplasm
Don’t worry about the subtypes.
Ductal adenocarcinoma: risk factors?
Chronic pancreatitis incr risk 10-15x
Cig smoking incr risk 2-3x
T2DM incr risk 2x
Hereditary pancreatitis incr risk 50x
CF incr risk as well.
Bottom line: not much that you can control; don’t smoke!
Pancreas cancar: what is the 5yr survival rate relative to other cancers (breast, colon, esop, liver)?
VERY LOW 5yr survival. Around 5% (don’t need to know number)
Why is pancreatic cancer such a bad disease?
- Early diagnosis is rare. There’s no self-exam, no cytologic screening, no antigen to test for.
- Usually it’s not noticed until there is pain or jaundice, by which time it is advanced.
Why is it so hard to excise pancreatic tumors? What structures are nearby?
(pic of tumor in the head of the panc)
Majority of cancers occur in the head of the panc.
Proximity to major vessels means that you cannot widely excise tissue.
May extend into retroperitoneal tissues
Structures: portal vein, superior mesenteric vessels and nerves, spleen, adrenals, vertebral column, transverse colon, and stomach
Besides nearby structures, another reason it is so hard to excise pancreatic tumors?
Perineural invasion is common in panc carcinoma.
Most tumors recur at the head of the pancreas, which is very nerve-rich.
Trends concerning pancreatic cancer:
- as grade of carcinoma increases, what happens to survival?
- the majority of cancers are what grades?
-as carcinoma grade increases, survival drops.
-the majority of cancers are grade 2 or higher.
INfluence of genetics in panc adenocarcinomas: what genes are involved? typically a single mutation or several?
There are mult genes that are mutated in panc adenocarcinomas. Most common are K-ras, p15, p53 and DPC4.
Most tumors are result of multiple mutations, not just one.
What is PanIN?
**Premalignant change in ductal epithelium. **
characterized by columnar to cuboidal cells, with mucin and some arthitectural atypia.
Common in older people, part of genesis of ductal adenocarcinoma
PanINs involved ducts <5mm in diameter.
What is this?
PanIN3 (carcinoma in situ - premalignant change in ductal epithelium)
epithelial neoplasm arising in pancreatic ducts.
some free-floating abnormal cells in this duct.
These are PanINs of various grades. What is notable on each?
Left: MILD. nuclei are small, at base of epithelium. Main change is overgrowth of epithelium and mucinous metaplasia. More mucus here than in normal duct cells
Center: MODERATE. enlarged nuclei, beginning to move away from basement membrane.
Right: ADVANCED. significant cytologic growth/abnormalities. Carcinoma in situ. If you find this, may do pancreatectomy to prevent cancer.
This is the progression model for pancreatic ductal carcinoma. What is occuring at each stage?
Left/normal: note cells not very mucinous.
PanIN-1a: cells have become papillary
PanIN-1b: cells no longer flat
PanIN-2: nuclear enlargement, movement of nuclei away from BM.
PanIN-3: cytologic abnormalities.
Note associated with genes (K-ras ->p16 -> p53 -> DPC4)
Panc cancer: is there any good news?
Not all pancreatic neoplasms are malignant.
May be benign, or in situ.
May be a cystic neoplasm (benign) that has been mistaken for a cystic tumor.
Possible that it is pancreatitis that looks like a neoplasm on imaging.