A 45-year-old woman undergoes colonoscopy because of a family history of CRC affecting her father aged 43 and brother aged 47, and endometrial cancer in a paternal aunt. At colonoscopy, she is found to have four adenomatous polyps and an adenocarcinoma of the sigmoid colon. Subsequent genetic testing confirms the diagnosis of Lynch syndrome (HNPCC).
Which of the following statements is the most accurate?
1-The inheritance of this condition is autosomal recessive
2-Genetic testing will confirm multiple germline mutations of mismatch repair genes
3-The median age of development of CRC is 45
4-The genetic defect is an example of CIN
5-Affected individuals are usually found to have hundreds of colonic polyps
Answer 3.
ReplyDeleteThe median age of development of CRC is 45.
Lynch syndrome is autosomal dominant, caused by germline
mutation of a single mismatch repair gene. Large
numbers of colorectal polyps are not characteristic of this
condition. Affected individuals are at increased risk of
extracolonic malignancy, particularly ovarian and endometrial
cancers. The genetic defect is an example of
microsatellite rather than CIN. The median age of development of CRC is 45.
Which of the following statements is correct concerning the relationship between type 2 diabetes and colonic cancer?
ReplyDelete1-Increased concentrations of C peptide are a marker of increased colorectal cancer risk
2-Insulin treatment increases recurrence free survival after treatment of colonic cancer
3-The increased risk of colorectal cancer in diabetes is related to BMI
4-The increased risk of colorectal cancer in diabetes is related to total cholesterol
5-Type 1 diabetes has similar risks of colonic cancer as does type 2 diabetes
Type 2 diabetes is associated with a 40-60% increase in the risk of cancer of the large bowel. This increase is linked to changes in HbA1c.
Type 2 diabetes is associated with significantly higher rates of overall mortality and reduced disease free and recurrence free survivals after chemotherapy/radiotherapy and insulin has not been shown to have any effects on mortality.
No association has been found between colonic malignancy and type 1 diabetes, nor gestational diabetes.
A number of studies have independently linked high circulating concentrations of C peptide, as a marker of insulin production, with increased colorectal cancer risk. The molecular basis has not been proven but it may be reasonable to extrapolate it is linked to the growth stimulation effects of insulin.
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