Lynch syndrome-associated breast cancers do not overexpress chromosome 11-encoded mucins.

Mismatch repair-deficient breast cancers may be identified in Lynch syndrome mutation carriers, and have clinicopathological features in common with mismatch repair-deficient colorectal and endometrial cancers such as tumour-infiltrating lymphocytes and poor differentiation. Mismatch repair-deficient colorectal cancers frequently show mucinous differentiation associated with upregulation of chromosome 11 mucins. The aim of this study was to compare the protein expression of these mucins in mismatch repair-deficient and -proficient breast cancers. Cases of breast cancer (n=100) were identified from families where (1) both breast and colon cancer co-occurred and (2) families met either modified Amsterdam criteria or had at least one early-onset (<50 years) colorectal cancer. Tumour sections were stained for the epithelial mucins, MUC2, MUC5AC, MUC5B and MUC6, and the homeobox protein CDX2, a regulator of MUC2 expression. In all, 16 mismatch repair-deficient Lynch syndrome breast cancers and 84 non-Lynch breast cancers were assessed for altered mucin expression. No significant difference in the expression of MUC2, MUC5AC or MUC6 was observed between the mismatch repair-deficient and mismatch repair-proficient breast cancers; however, there was a trend for mismatch repair-deficient tumours to express high levels of MUC5B less frequently (P=0.07, OR=0.2 (0.0-1.0)). Co-expression of two or more gel-forming mucins was common. Ectopic expression of CDX2 was associated with expression of MUC2 (P=0.035, OR=8.7 (1.3-58.4)). Mismatch repair-deficient breast cancers do not show differential expression of the mucins genes on chromosome 11 when compared with mismatch repair-proficient breast cancers, in contrast with mismatch repair-deficient colorectal and endometrial cancers, which frequently have increased mucin protein expression when compared with their mismatch repair-proficient counterparts. In addition, ectopic CDX2 expression is positively associated with de novo MUC2 expression.

Immunohistochemistry to detect hereditary nonpolyposis colorectal cancer in young patients: the 7-year Auckland experience.

BACKGROUND: In accordance with the Bethesda Guidelines, Auckland's metropolitan hospitals routinely perform immunohistochemistry for mismatch repair proteins on the tumor specimens of all patients with colorectal cancer aged 50 years and younger. When loss of expression is evident, patients are offered genetic counseling and gene mutation analysis. OBJECTIVES: This study aimed to determine the completeness of young patient capture over the first 7 years of routine testing, to find whether patients were referred for genetic testing, and to determine the proportion of patients found to have a mismatch repair gene mutation. DESIGN: This study retrospectively reviewed clinical, pathological, and genetic data. SETTINGS: The study was conducted at 3 public hospitals in Auckland, New Zealand. PATIENTS: All patients aged 50 years and younger treated for colorectal cancer at Auckland's metropolitan hospitals between January 2001 and December 2007 (n = 243) were included. MAIN OUTCOME MEASURES: The loss of expression of mismatch repair proteins by immunohistochemistry, referral for genetic testing, and proportion with mismatch repair gene mutation were the main outcome measures. RESULTS: Two hundred fourteen (88%) eligible patients had immunohistochemical analysis of their tumor and 33 (14%) had loss of expression of one or more mismatch repair proteins. Twenty-six patients were referred for genetic counseling, of whom 22 underwent genetic testing. A mismatch repair gene mutation was identified in 10 patients. LIMITATIONS: Seven patients with loss of expression of mismatch repair proteins by immunohistochemistry were not referred for genetic assessment. CONCLUSIONS: We have identified a mismatch repair gene mutation diagnostic of hereditary nonpolyposis colorectal cancer in 5% of all patients with colorectal cancer who were aged 50 years and younger. Routine immunohistochemical prescreening has important clinical benefit for these patients and their relatives.

How do researchers manage genetic results in practice? The experience of the multinational Colon Cancer Family Registry.

There is consensus internationally that research participants should be offered the opportunity to receive clinically relevant genetic information identified through research, but there is little empirical peer-reviewed work documenting this process. We report the experience of conducting genetic research with nearly 35,000 participants in the Colon Cancer Family Registry, based in the USA, Canada, Australia, and New Zealand. Investigators from six multinational sites provided information about disclosure protocols, implementation, and uptake of genetic results and made suggestions to inform practice. Across 5 of the 6 registry sites, 1,634 participants in families with mismatch repair or MutYH gene mutations have been offered results. Participant uptake ranged from 56 to 86 %. Researchers faced significant challenges in the effort to return results. We offer suggestions in five key areas: (1) planning for the disclosure process, (2) participant information, (3) autonomy of participants, (4) monitoring scientific progress, and (5) involvement of stakeholders. Despite increasing discussion of the importance of returning incidental findings from genetic research, this paper highlights the considerable diversity, challenges, and costs faced in practice when returning expected findings with established utility and validity. We argue that more work is needed to ensure that genetic results in research are optimally managed.