High risk of endometrial cancer in colorectal cancer kindred is pathognomonic for MMR-mutation carriers

Mismatch repair is a double-edged sword in the battle against microsatellite instability

Roughly 3% of the human genome consists of microsatellites or tracts of short tandem repeats (STRs). These STRs are often unstable, undergoing high-frequency expansions (increases) or contractions (decreases) in the number of repeat units. Some microsatellite instability (MSI) is seen at multiple STRs within a single cell and is associated with certain types of cancer. A second form of MSI is characterised by expansion of a single gene-specific STR and such expansions are responsible for a group of 40+ human genetic disorders known as the repeat expansion diseases (REDs). While the mismatch repair (MMR) pathway prevents genome-wide MSI, emerging evidence suggests that some MMR factors are directly involved in generating expansions in the REDs. Thus, MMR suppresses some forms of expansion while some MMR factors promote expansion in other contexts. This review will cover what is known about the paradoxical effect of MMR on microsatellite expansion in mammalian cells.

Feasibility of endometrial sampling by vaginal tampons in women with Lynch syndrome

Background

Endometrial sampling for the surveillance of women with Lynch syndrome is an invasive and painful procedure. The aim of this study was to evaluate the feasibility of a less invasive procedure of collecting vital cells by vaginal tampons.

Methods

This was a prospective feasibility study of women scheduled to undergo annual gynecological surveillance, including endometrial sampling. We included consecutive asymptomatic women with Lynch syndrome or first-degree relatives and asked them to insert a vaginal tampon 2–4 h before attending their outpatient appointment. Feasibility was evaluated by the following metrics: patient acceptance, pain intensity of each procedure (assessed by visual analog scale; range 0–10), and the presence of vital cells obtained by tampon-based or endometrial sampling methods. Two pathologists independently evaluated all samples.

Results

In total, 25 of 32 approached women completed the tampon-based procedure, with 23 of these subsequently undergoing invasive endometrial sampling. The median visual analog scale scores for tampon use and invasive endometrial sampling were 0 (range, 0–10) and 5.5 (range, 1–10) (p < 0.001). None of the tampon samples analyzed by cytology showed endometrial cells, but they did contain vital squamous cells and granulocytes. By contrast, 18 (78%) of the invasive endometrial samples contained enough endometrial tissue for analysis. No endometrial abnormalities were found by endometrial sampling.

Conclusions

Tampon-based endometrial surveillance was a well-accepted and non-painful procedure, and although tampons contained vital cells, they did not provide endometrial cells. However, this study was limited to asymptomatic women with Lynch syndrome (no endometrial pathology), indicating that research is needed to evaluate whether the tampon method has any utility for endometrial surveillance in women with Lynch syndrome.

Cancer risk and survival in path_MMR carriers by gene and gender up to 75 years of age: a report from the Prospective Lynch Syndrome Database

BACKGROUND

Most patients with path_MMR gene variants (Lynch syndrome (LS)) now survive both their first and subsequent cancers, resulting in a growing number of older patients with LS for whom limited information exists with respect to cancer risk and survival.

OBJECTIVE AND DESIGN

This observational, international, multicentre study aimed to determine prospectively observed incidences of cancers and survival in path_MMR carriers up to 75 years of age.

RESULTS

3119 patients were followed for a total of 24 475 years. Cumulative incidences at 75 years (risks) for colorectal cancer were 46%, 43% and 15% in path_MLH1, path_MSH2 and path_MSH6 carriers; for endometrial cancer 43%, 57% and 46%; for ovarian cancer 10%, 17% and 13%; for upper gastrointestinal (gastric, duodenal, bile duct or pancreatic) cancers 21%, 10% and 7%; for urinary tract cancers 8%, 25% and 11%; for prostate cancer 17%, 32% and 18%; and for brain tumours 1%, 5% and 1%, respectively. Ovarian cancer occurred mainly premenopausally. By contrast, upper gastrointestinal, urinary tract and prostate cancers occurred predominantly at older ages. Overall 5-year survival for prostate cancer was 100%, urinary bladder 93%, ureter 85%, duodenum 67%, stomach 61%, bile duct 29%, brain 22% and pancreas 0%. Path_PMS2 carriers had lower risk for cancer.

CONCLUSION

Carriers of different path_MMR variants exhibit distinct patterns of cancer risk and survival as they age. Risk estimates for counselling and planning of surveillance and treatment should be tailored to each patient's age, gender and path_MMR variant. We have updated our open-access website www.lscarisk.org to facilitate this.

Characteristics of Lynch syndrome associated ovarian cancer

OBJECTIVE

To describe clinical characteristics of Lynch syndrome associated ovarian cancer and the efficacy of surveillance in the early detection of these ovarian cancers.

METHODS

All Lynch syndrome associated ovarian cancer cases identified in either the Dutch Lynch syndrome registry (DLSR) between 1987 and 2016, and/or the cohort at the University Medical Center Groningen (UMCG) between 1993 and 2016 were included. Clinical data on age at diagnosis, mutation type, histological type, FIGO stage, treatment, follow-up and gynecological surveillance were collected.

RESULTS

A total of 46/798 (6%) women in the DLSR and 7/80 (9%) in the UMCG cohort were identified as LS associated ovarian cancer patients. The median age at ovarian cancer diagnosis was 46.0 years (range 20-75 years). The most frequently reported histological type was endometrioid adenocarcinoma (40%; n = 21) and serous carcinoma (36%; n = 19). Most tumors (87%; n = 46) were detected at an early stage (FIGO I/II). Forty-one of 53 (77%) patients were diagnosed with ovarian cancer before LS was diagnosed. In the other 12/53 (23%) women, ovarian cancer developed after starting annual gynecological surveillance for LS; three ovarian cancers were screen-detected in asymptomatic women. Overall survival was 83%.

CONCLUSION

Ovarian cancer in women with LS has a wide age-range of onset, is usually diagnosed at an early stage with predominantly endometrioid type histology and a good overall survival. The early stage at diagnosis could not be attributed to annual gynecological surveillance.

Spectrum of mismatch repair gene mutations and clinical presentation of Hispanic individuals with Lynch syndrome

Lynch syndrome (LS), the most common hereditary colorectal cancer syndrome, is caused by mismatch repair (MMR) gene mutations. However, data about MMR mutations in Hispanics are limited. This study aims to describe the spectrum of MMR mutations in Hispanics with LS and explore ancestral origins. This case series involved an IRB-approved retrospective chart review of self-identified Hispanic patients (n = 397) seen for genetic cancer risk assessment at four collaborating academic institutions in California, Texas, and Puerto Rico who were evaluated by MMR genotyping and/or tumor analysis. A literature review was conducted for all mutations identified. Of those who underwent clinical genetic testing (n = 176), 71 had MMR gene mutations. Nine mutations were observed more than once. One third (3/9) of recurrent mutations and two additional mutations (seen only once) were previously reported in Spain, confirming the influence of Spanish ancestry on MMR mutations in Hispanic populations. The recurrent mutations identified (n = 9) included both previously reported mutations as well as unique mutations not in the literature. This is the largest report of Hispanic MMR mutations in North America; however, a larger sample and haplotype analyses are needed to better understand recurrent MMR mutations in Hispanic populations.

The additional value of endometrial sampling in the early detection of endometrial cancer in women with Lynch syndrome

OBJECTIVE

Based on previous studies, standard gynecological screening consisting of annual transvaginal ultrasonography (TVU) was added with endometrial sampling in women with Lynch syndrome (LS). The aim of this study was to evaluate the additional value of endometrial sampling in detecting (pre)malignancies of the endometrial tissue in women with LS or first-degree relatives.

METHODS

All women above 30 years of age with LS or first-degree relatives at 50% risk of LS are offered annual gynecological screening in our family cancer clinic. Endometrial screening results from January 2003-December 2007 (period I: standard screening by transvaginal sonography and serum CA125) were compared with screening results from January 2008-June 2012 (period II: standard screening added with endometrial sampling).

RESULTS

Seventy five women (300 patient years) were screened annually. There were 266 screening visits, 117 in period I and 149 in period II. In period I, four premalignant endometrial lesions were detected and one endometrial carcinoma (FIGO stage IB). In period II, two premalignancies were found. None of the lesions would have been missed without standard endometrial sampling. No interval endometrial cancers were detected in this study.

CONCLUSION

In this study, annual endometrial screening seems an effective screening tool in the detection of premalignancies and early endometrial cancer in women with LS. Adding standard endometrial sampling to annual TVU has no additional value in the early detection of (pre)malignant endometrial lesions in women with LS in this study.

Identification of a founder EPCAM deletion in Spanish Lynch syndrome families

Germline deletions at the 3'-end of EPCAM have been involved in the etiology of Lynch syndrome (LS). The aim of this study was to characterize at the molecular level Spanish families harboring EPCAM deletions. Non-commercial multiplex ligation-dependent probe amplification (MLPA) probes and long-range polymerase chain reaction (PCR) amplification were used to characterize each deletion. Haplotyping was performed by analyzing eight microsatellite markers and five MSH2single nucleotide polymorphisms (SNPs). Methylation of MSH2 was analyzed by methylation specific-MLPA. Tumors diagnosed in seven Spanish families harboring EPCAM deletions were almost exclusively colorectal. Mosaicism in MSH2 methylation was observed in EPCAM deletion carrier samples, being average methylation levels higher in normal colon and colorectal tumors (27.6% and 31.1%), than in lymphocytes and oral mucosa (1.1% and 0.7%). Three families shared the deletion c.858 + 2568_*4596del, with a common haplotype comprising 9.9 Mb. In two families the novel EPCAM deletion c.858 + 2488_*7469del was identified. This study provides knowledge on the clinical and molecular characteristics of mosaic MSH2 epimutations. The identification of an EPCAM founder mutation has useful implications for the molecular diagnosis of LS in Spain.

Screening for gynaecologic cancers in genetically predisposed women

Hereditary breast and ovarian cancer syndrome and hereditary non-polyposis colon cancer syndrome are the two most important syndromes responsible for inherited cancers in gynaecology. Genetic testing is available for both these syndromes. Breast cancer gene testing is affordable and easy in women with ancestry where the mutation patterns are known, whereas other population groups need full gene screening. Hereditary non-polyposis colon cancer syndrome can now be diagnosed more frequently with the use of immunohistochemistry. Ovarian cancer risk is high in hereditary breast and ovarian cancer syndromes, and advanced screening techniques should be used when preventive surgery is not an option. Early detection techniques offer less protection than prophylactic removal, but enable women to retain their reproductive organs. Oophorectomy has the advantage of reducing breast cancer risk. In colorectal cancer syndromes, the risk for endometrial and ovarian cancer is much elevated. These risks should be recognised and addressed as these diseases are easy to prevent.