Lynch syndrome (LS) is characterised by the development of colorectal cancer, endometrial cancer and various other cancers, and is caused by a mutation in one of the mismatch repair genes: MLH1, MSH2, MSH6 or PMS2. In 2007, a group of European experts (the Mallorca group) published guidelines for the clinical management of LS. Since then substantial new information has become available necessitating an update of the guidelines. In 2011 and 2012 workshops were organised in Palma de Mallorca. A total of 35 specialists from 13 countries participated in the meetings. The first step was to formulate important clinical questions. Then a systematic literature search was performed using the Pubmed database and manual searches of relevant articles. During the workshops the outcome of the literature search was discussed in detail. The guidelines described in this paper may be helpful for the appropriate management of families with LS. Prospective controlled studies should be undertaken to improve further the care of these families.

PMS2 cause Lynch syndrome and result in different but imprecisely known cancer risks. This study aimed to provide age and organspecific cancer risks according to gene and gender and to determine survival after cancer. Methods: We conducted an international, multicenter prospective observational study using independent test and validation cohorts of carriers of class 4 or class 5 variants. After validation the cohorts were merged providing 6350 participants and 51,646 followup years. Results: There were 1808 prospectively observed cancers. Pathogenic MLH1 and MSH2 variants caused high penetrance dominant cancer syndromes sharing similar colorectal, endometrial, and ovarian cancer risks, but older MSH2 carriers had higher risk of cancers of the upper urinary tract, upper gastrointestinal tract, brain, and particularly prostate. Pathogenic MSH6 variants caused a sex-limited trait with high endometrial cancer risk but only modestly increased colorectal cancer risk in both genders. We did not demonstrate a significantly increased cancer risk in carriers of pathogenic PMS2 variants. Ten-year crude survival was over 80% following colon, endometrial, or ovarian cancer. Conclusion: Management guidelines for Lynch syndrome may require revision in light of these different gene and gender-specific risks and the good prognosis for the most commonly associated cancers.

A B S T R A C T PurposePatients with Lynch syndrome are at high risk for colon and endometrial cancer, but also at an elevated risk for other less common cancers. The purpose of this retrospective cohort study was to provide risk estimates for these less common cancers in proven carriers of pathogenic mutations in the mismatch repair (MMR) genes MLH1, MSH2, and MSH6. Patients and MethodsData were pooled from the German and Dutch national Lynch syndrome registries. Seven different cancer types were analyzed: stomach, small bowel, urinary bladder, other urothelial, breast, ovarian, and prostate cancer. Age-, sex-and MMR gene-specific cumulative risks (CRs) were calculated using the Kaplan-Meier method. Sex-specific incidence rates were compared with general population incidence rates by calculating standardized incidence ratios (SIRs). Multivariate Cox regression analysis was used to estimate the impact of sex and mutated gene on cancer risk. ResultsThe cohort comprised 2,118 MMR gene mutation carriers (MLH1, n ϭ 806; MSH2, n ϭ 1,004; MSH6, n ϭ 308). All cancers were significantly more frequent than in the general population. The highest risks were found for male small bowel cancer (SIR, 251; 95% CI, 177 to 346; CR at 70 years, 12.0; 95% CI, 5.7 to 18.2). Breast cancer showed an SIR of 1.9 (95% CI, 1.4 to 2.4) and a CR of 14.4 (95% CI, 9.5 to 19.3). MSH2 mutation carriers had a considerably higher risk of developing urothelial cancer than MLH1 or MSH6 carriers. ConclusionThe sex-and gene-specific differences of less common cancer risks should be taken into account in cancer surveillance and prevention programs for patients with Lynch syndrome.

Summary BACKGROUND Lynch syndrome is caused by germline mutations in mismatch repair genes (MSH2, MLH1, MSH6 or PMS2), which lead to a high risk of predominantly colorectal and endometrial cancer. Recently, we found that also constitutional 3′ end deletions of EPCAM can cause Lynch syndrome through epigenetic silencing of MSH2 in EPCAM expressing tissues. This results in a tissue specific MSH2-deficiency, which may evoke a different cancer risk and spectrum. To optimize the care for EPCAM deletion carriers we studied their cancer risk and spectrum. METHODS Clinical data of 194 carriers from 41 EPCAM families were systematically collected and compared to those of 431 carriers from 91 families with mutations in MLH1, MSH2, or MSH6. FINDINGS EPCAM deletion carriers exhibited a 75% [95%CI 65–85%] cumulative risk of colorectal cancer before the age of 70 years, with a mean age at diagnosis of 43 years, which is comparable to that of carriers of a combined EPCAM-MSH2 deletion (69% [95%CI 47-91%], p=0·8609) or of a mutation in MSH2 (77% [95%CI 64-90%], p=0·5892) or MLH1 (79% [95%CI 68-90%], p=0·5492) and higher than that of MSH6 mutation carriers (50% [95%CI 38-62%], p<0·0001). In contrast, women with EPCAM deletions (n=87) exhibited a 12% [95%CI 0-27%] cumulative risk of endometrial cancer, which is significantly lower than in carriers of a combined EPCAM-MSH2 deletion (55% [95%CI 20-90%], p<0·0001) or of a mutation in MSH2 (51% [95%CI 33-69%], p=0·0006) or MSH6 (34% [95%CI 20-48%], p=0·0309) and lower than in MLH1 (33% [95%CI 15-51%] p=0·1193) mutation carriers. This risk seems to be restricted to large deletions that extend close to the MSH2 gene promoter. Overall, a relatively high incidence of duodenal (n=3) and pancreatic (n=4) cancers was observed. INTERPRETATION EPCAM deletion carriers do have a high risk of colorectal cancer. Only those with deletions extending close to the MSH2 promoter have an increased risk of endometrial cancer. These results underscore the impact of mosaic MSH2-deficiency on cancer risk and are indicative for a protocol revision for surveillance and preventive surgery in EPCAM deletion carriers.

CRC and EC risks were found to be markedly lower than those previously reported for the other MMR. However, these risks embody the isolated risk of carrying a PMS2 mutation, and it should be noted that we observed a substantial variation in cancer phenotype within and between families, suggesting the influence of genetic modifiers and lifestyle factors on cancer risks.

Our data provide guidance for healthcare professionals and decision-makers to identify individuals who should undergo genetic testing for hereditary breast and ovarian cancer. Moreover, it supports informed decision-making of counselees on the uptake of genetic testing.

Heterozygous PMS2 mutation carriers were at small increased risk for colorectal and endometrial cancer but not for any other Lynch syndrome-associated cancer. This finding justifies that PMS2-specific screening protocols could be restricted to colonoscopies. The role of risk-reducing hysterectomy and bilateral salpingo-oophorectomy for PMS2 mutation carriers needs further discussion.

Recently, we identified 3' end deletions in the EPCAM gene as a novel cause of Lynch syndrome. These truncating EPCAM deletions cause allele-specific epigenetic silencing of the neighboring DNA mismatch repair gene MSH2 in tissues expressing EPCAM. Here we screened a cohort of unexplained Lynch-like families for the presence of EPCAM deletions. We identified 27 novel independent MSH2-deficient families from multiple geographical origins with varying deletions all encompassing the 3' end of EPCAM, but leaving the MSH2 gene intact. Within The Netherlands and Germany, EPCAM deletions appeared to represent at least 2.8% and 1.1% of the confirmed Lynch syndrome families, respectively. MSH2 promoter methylation was observed in epithelial tissues of all deletion carriers tested, thus confirming silencing of MSH2 as the causative defect. In a total of 45 families, 19 different deletions were found, all including the last two exons and the transcription termination signal of EPCAM. All deletions appeared to originate from Alu-repeat mediated recombination events. In 17 cases regions of microhomology around the breakpoints were found, suggesting nonallelic homologous recombination as the most likely mechanism. We conclude that 3' end EPCAM deletions are a recurrent cause of Lynch syndrome, which should be implemented in routine Lynch syndrome diagnostics.