The impact of new screening protocol on individuals at increased risk of colorectal cancer

Colonoscopy findings in high-risk individuals compared to an average-risk control population

BACKGROUND AND AIMS

There is clear evidence of reduced morbidity and mortality from regular colonoscopy programs in patients with Lynch syndrome (LS). Today, also individuals with empirically increased risks of colorectal cancer (CRC) are offered colonoscopic surveillance. The aim was to compare the findings at the first screening colonoscopy in LS carriers, and individuals with an increased risk of bowel cancer due to family history of CRC with a control population.

METHODS

Altogether 1397 individuals with an increased risk for CRC were divided in four risk groups: one with LS carriers and three groups with individuals with different family history of CRC. The findings were compared between the different risk groups and a control group consisting of 745 individuals from a control population who took part in a population-based colonoscopy study.

RESULTS

In LS, 30% of the individuals had adenomas and 10% advanced adenomas. The corresponding figures in the other risk groups were 14-24% and 4-7%, compared with 10% and 3% in the control group. The relative risk of having adenomas and advanced adenomas was, compared to controls, significantly higher for all risk groups except the group with the lowest risk. Age was a strong predictor for adenomas and advanced adenomas in both risk individuals and controls.

CONCLUSIONS

Individuals with a family history of CRC have a high prevalence and cumulative risk of adenomas and advanced adenomas, and screening is motivated also in this risk group.

Hyperplastic polyps are innocuous lesions in hereditary nonpolyposis colorectal cancers

Aims. To compare methylation profiles, protein expression, and microsatellite instability (MSI) of sporadic, HNPCC, and familial hyperplastic polyps (HPs). Methods. Methylation-specific PCR (MSP) and pyrosequencing assessed p16, MGMT, hMLH-1, MINT 1, and MINT 31 methylation. IHC (Immunohistochemistry) assessed Ki67, CK20, hMLH-1, hMSH-2, and hMSH-6 protein expression. MSI analysis was performed on those polyps with adequate DNA remaining. Results. 124 HPs were identified 78 sporadic, 21 HNPCC, 25 familial, and the HNPCC group demonstrated no significant differences in overall methylation (P = .186 Chi²). The familial group demonstrated significantly less over all methylation levels (P = .004 Chi²). Conclusions. HPs that occur in HNPCC have no more worrying features at a molecular level than those patients with HPs in a sporadic setting.

Microsatellite instability and mismatch repair protein defects in ovarian epithelial neoplasms in patients 50 years of age and younger

Ovarian malignancies occurring in the setting of hereditary nonpolyposis colorectal carcinoma syndrome typically present in young women, often as the first or "sentinel" cancer, but the frequency of microsatellite instability (MSI) and mismatch repair (MMR) defects in ovarian surface epithelial malignancies in women <or=50 years of age is neither well known nor well tested. Fifty-two ovarian surface epithelial carcinomas, including 4 with synchronous endometrial carcinomas, were identified in patients 50 years of age or younger and evaluated for evidence of MSI and MMR protein deficiency. Each case was tested for MSI by multiplex polymerase chain reaction amplification of the National Cancer Institute reference panel (BAT25, BAT26, D2S123, D5S346, and D17S250) and deficiency of MMR protein expression by immunohistochemistry (MLH1, MSH2, MSH6, and PMS2). MMR protein expression and MSI (in a subset of cases) were also evaluated in 50 unselected ovarian serous tumors of low malignant potential , a tumor common in younger women. Defects in MMR were detected in 5 of 52 (10%) ovarian carcinomas by at least 1 testing method, including 2 of 4 (50%) ovarian cancers presenting with synchronous endometrial cancer. Three of the 5 (60%) ovarian carcinomas were clear cell carcinomas (17% of all pure clear cell carcinomas) and the remaining 2 were high-grade carcinomas with endometrioid and mixed histology. Loss of MSH2 and MSH6 was detected in all of the affected clear cell carcinomas and a synchronous endometrial cancer with endometrioid histology. Loss of 1 or more MMR proteins was initially noted in 10/50 ovarian serous tumors of low malignant potential on tissue microarray, but further testing on full tissue sections showed intact protein expression and microsatellite stability in all informative cases. This study demonstrates a 10% rate of MMR-deficient ovarian cancer in women <or=50 years of age. MMR-deficient ovarian cancer is frequently associated with loss of expression of MSH2 and MSH6 proteins and clear cell histology. The occurrence of MMR inactivation in a significant proportion of ovarian clear cell carcinomas (17% in this study) suggests that this tumor may warrant targeted testing in women <or=50 years of age.