Impact of colonoscopy screening on individuals at high risk of hereditary nonpolyposis colorectal cancer (HNPCC)

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Background: Colonoscopy screening reduces the incidence of, and mortality from, colorectal cancer (CRC) in individuals with HNPCC. The aim of this study was to determine the impact of colonoscopic follow-up in individuals at high risk of HNPCC, in terms of detection of precursor lesions (adenomas) or cancer.

Methods: Between 2005-2008, 163 individuals with HNPCC were advised to undergo regular follow-up colonoscopy. Compliance and results of the scans were evaluated annually and were verified with medical documentation.

Results: Of the 125 individuals who underwent at least one colonoscopy during the follow-up period of colonoscopy screening, in 33 subjects (26%) at least one colonic adenoma was detected. The median number of adenomas detected per colonoscopy in individuals with polyps was 2. The number of colonoscopies with polyps did not differ between women and men. However, the number of polyps removed by colonoscopy and the total number of polyps removed during the follow-up period was significantly higher in men (p = 0.005, p = 0.05 bilateral, respectively). 5 individuals (4%) were diagnosed with CRC, one of whom had two synchronous tumors. Of these, four individuals had properly followed the screening recommendations with the recommended frequency. In the case where two synchronous tumors were detected, it was the first colonoscopy screening that had been performed on the individual. None had had cancer previously, they were healthy relatives of an index case. All except one belonged to families that fulfilled the Amsterdam criteria I / II. All the tumors were diagnosed at an early stage, except two, which exhibited positive nodes.

Conclusions: Colonoscopy screening is effective in diagnosing colorectal adenomas and cancer in individuals with HNPCC. Men with HNPCC have a greater number of colorectal adenomas. Screening allows the detection of colorectal cancer at an early stages. Funded by a young researcher's grant from the Spanish Society of Medical Oncology 2006.

No significant financial relationships to disclose.

Correlation between clinical-pathological parameters and family history to detect mutations in MLH1, MSH2, and MSH6

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Background: The Amsterdam I/II and Bethesda criteria are used to select individuals for the study of mutations in hereditary nonpolyposis colon cancer (HNPCC). The aim of this study was to analyze whether specific clinical features and family history of individuals suspected of HNPCC were correlated with the detection of germline mutations in MLH1, MSH2 and MSH6.

Methods: Between 2005-2008, the study of germline mutations in one or more of the genes MLH1, MSH2 or MSH6 was carried out on 124 individuals who fullfield the Amsterdam I/II criteria or Bethesda criteria with microsatellite instability (MSI) or loss of expression by immunohistochemistry (IHC) of any of the repair proteins of MMR genes. Subsequently, we applied univariate and multivariate analyses including clinicopathological characteristics and family history to see if they were related to the presence of germline mutations. The characteristics were: age, sex, age at diagnosis, whether they fulfilled the Amsterdam or Bethesda criteria, diagnosis of cancer, tumor type, presence of multiple tumors and age of first diagnosis of cancer in the family.

Results: Out of 124 patients studied, 29 gene mutations were detected (detection rate 25%). Of all the parameters studied, only endometrial cancer increased the risk of mutation 7.3 times (confidence interval [CI] 95%, from 1.83 to 29.2) for colorectal cancer (p = 0.005). 20.7% of mutations in MMR genes were explained by the type of cancer (R square Nagelkerke = 0.207). In the multivariate analysis none of the variables predicted the presence of mutation.

Conclusions: The most important clinical feature to predict the presence of a mutation in the genes MLH1, MSH2 and/or MSH6 in families with HNPCC is the diagnosis of endometrial cancer (univariate analysis).

No significant financial relationships to disclose.