Cancer Prevention, Detection, and Chemotherapy 4
Now, some of you are aware of the Lynch Syndrome I and there’s a Lynch Syndrome II. It’s a very interesting type of illness. The mean age of onset is 45. It’s found in the proximal colon so when you’re trying to get it and find it and reverse the deaths due to the colon cancer, you have to think about the proximal colon. It has an unusually good prognosis which is usually found in all these types of syndromes and it’s an autosomally dominant type of inheritance.
Lynch Syndrome II is the same as I except multiple tumors, high frequency of colon, endometrium and ovary and less frequent breast, stomach and lymphoma. I have to bring this up because there’s a lot of fights and discussions over in Europe particularly about these two entities and the people felt that this really didn’t jive – that there wasn’t an increased incidence in these Lynch syndrome II. However, they found a number of families with this kind of a syndrome and it pretty well cleared this up. Indeed, this is a cause by the high incidence of the various types of cancers that are listed there.
Here’s a family that’s pretty prolific and as you can see there are seven cases with cancer and five without and you can see the various ages that they had this. Here’s one at 46 years of age. Here’s another one at 55, 42 and certainly a real problem and some of these patients get to the point they just don’t want to talk about it anymore and don’t get the proper studies that they should be getting.
The hereditary aspects of colorectal, again, in familial adenomatous polyposis, percent of colon cancers is less than 1% interestingly enough and that’s one that gets a lot of publicity. Chromosome 5Q21 and gene APC are found. In hereditary nonpolyposis you can see the incidence goes up from 1% to 9%. Chromosome is 2Q3P and then it’s chromosome COCA-1 which you probably know about as well as I do. Now when we’re screening for colorectal cancer, you want to do a digital rectal every year starting age 40. Fecal occult blood test every year age 50. Sigmoidoscopy every 3 to 5 years at age 50. Colonoscopy, first degree relatives of cancer patients at age 50 or less. Age 35 to 40, 2, 3 to 5 years for this test. You will find different groups will do this in a little bit different manner and you may not find the exact type of suggestions as is listed here.
Hemoccult testing. As you know, if the test is positive, 10% of these patients will have cancer and 23% will have polyps. So it’s not a very good test in terms of getting all the cancer patients involved with this. The Hemoccult II only screening test if we use it only like that for asymptomatic colorectal cancer, 50-60% will remain undetected. So not the best test.So if you look at what we’re doing with colorectal cancer, occult blood is a poor marker for colorectal cancer. Most cancers are missed and most bleeding is due to other causes. The HemoQuant is a specific test for blood and some groups are using these too in their studies but there’s really no improvement in picking up the cancers by using this newer test. Both are equally insensitive and we need better screening markers in order to do better in detecting this.