Dr. Brian Loggie Answers Questions
Dr. Loggie answered questions presented by members of the PMP Pals’ Network who are concerned about the possibility of hereditary or environmental factors that may possibly be associated with Appendix Cancer/Pseudomyxoma Peritonei.
Is there any evidence that appendiceal cancer/Pseudomyxoma Peritonei is a hereditary or familial disease?
“We have investigated this issue closely here at Creighton University School of Medicine. Dr Henry Lynch, for whom Lynch Syndrome (familial colorectal cancer) was named, is a colleague and is Chair of Preventive Medicine here in our Hereditary Cancer Center.
To our surprise, we have NOT found a familial association for appendix neoplasms and Pseudomyxoma Peritonei. In fact, we have seen a rate of “familiality” (family history of colon or appendix tumors suggesting an inherited pattern in the family) that is less than expected by one fifth (based on risk from right sided colon cancer: about 1% versus 5%). Overall, I think this is good news for families.”
How often does appendiceal cancer occur?
“The relative estimate for incidence of appendix neoplasms is typically estimated at about 1% of the incidence of colorectal cancer. I think that is reasonable; if you take the average size of the appendix, extrapolate to mucosal area, and then compare that to the average size/area of the colon, you get a ratio of about 1%.”
Where does Pseudomyxoma Peritonei originate?
“Ninety nine per cent of Pseudomyxoma Peritonei cases originate with the appendix.
My sense is that a big difference between appendix neoplasms or “PMP”, and colon cancer is their location. The appendix arises embryologically as a diverticulum (out pouching) of the right colon, and is histologically similar to colon.”
What are some of the differences between appendiceal and colorectal cancer?
“We see appendix tumors diagnosed typically earlier than for colorectal cancer. Small adenomas progress sooner in the appendix, where they can rupture or infiltrate, causing problems leading to diagnosis based on the small size of the appendix.”
What are the causes of colon cancer?
“The current thoughts are that colon tumors develop out of a series of changes (cumulative mutations occurring in specific genes) occurring over a number of years, whereby adenomas (early non-malignant polyps) develop and grow, and can further evolve into cancers including malignant polyps or adenocarcinomas.
An adenoma, or cancer, growing in the colon has a lot more space (and therefore time) in order to grow before causing problems that lead to diagnosis.
Again, supportive of this is the earlier age of diagnosis of appendix cancer/Pseudomyxoma Peritonei patients and the approximate relative incidence (about 1% rather than ten times less or ten times more) seem to match in terms of an estimated percentage for the mucosal areas at risk.”
What are some of the some of the similarities between appendiceal and colon cancer?
“There seem to be more differences than similarities, in many cases, although there is overlapping pathology. We see a high percentage of KRAS mutations in PMP (about 65% for low grade PMP), higher than for colon cancer (around 30-40%). Our current research suggests that KRAS may be an early primary “driver” which is different for garden variety colon cancer which has a different early driver. The involvement of KRAS may also have implications for the exaggerated mucin production seen in PMP, and is a focus of our current studies in the laboratory.
The appendix is a diverticulum (literally defined as a “way house of ill-repute!”) that is not likely exposed to the continuous stream of stool, as is normal colon mucosa (and therefore perhaps less exposure to bile and environmental agents). This could also play a role in some observed differences.
These are my current observations; we have not seen an inherited basis for the majority of cases nor identified an environmental link.”
Dr. Brian W. Loggie, MD, CM, FRCSC, FACS is a Professor of Surgery and Chief of the Division of Surgical Oncology at Creighton University School of Medicine in Omaha, NE. He is also Director of the Cancer Biology Program there.
Dr. Loggie’s expertise includes the treatment of peritoneal carcinomatosis, peritoneal mesothelioma, pseudomyxoma peritonei and all peritoneal surface malignancies, abdominopelvic and retroperitoneal sarcomas, cutaneous malignant melanoma, sphincter-preserving treatment for rectal tumors, and management of complex primary or recurrent solid tumors.
Dr. Henry Lynch, MD is the Chair of Preventive Medicine in the Hereditary Cancer Center at Creighton University. Lynch has published more than 700 journal articles and books focused on diagnosis, prevention, and treatment of hereditary disorders, especially cancer. He has devoted much of his life to the study and research of family medical history data, leading him to identify cancer syndromes and their patterns of inheritance among generations of families. Lynch Syndrome, aka hereditary nonpolyposis colorectal cancer (HNPCC), is an inherited cancer affecting the digestive tract, especially the colon and rectum. Families with Lynch Syndrome have an increased risk of cancers of the stomach, small intestine, liver, gallbladder ducts, upper urinary tract, brain, skin, and prostate, and may be a cause of endometriosis.
For more information about Dr. Lynch and his work go to his page on the Creighton University School of Medicine website: http://medschool.creighton.edu/medicine/centers/erdn/welcome/