Carrier risk status changes resulting from mutation testing in hereditary non-polyposis colorectal cancer and hereditary breast-ovarian cancer

For Women, Lynch Syndrome Is About More than Colon Cancer

Lynch syndrome, also known as hereditary nonpolyposis colorectal cancer, has historically been characterized by a predisposition to colorectal cancer; however, for women with Lynch syndrome, the risks for gynecologic cancers pose an equal or greater risk than colorectal cancer. In addition, the gynecologic cancer is often the first cancer that presents in these patients. Also of importance to women with Lynch syndrome is the efficacy of gynecologic cancer screening being significantly lower than colorectal cancer screening, leading to inconsistency in provider recommendations for gynecologic screening and surveillance. We had the chance to listen to women with Lynch syndrome, in their own words, discuss their health care experiences as they relate to gynecologic cancer risk, and identified several important themes. They describe feeling confused about their screening and surveillance options while also being heavily reliant on their health care providers for guidance. In addition, women with Lynch syndrome discuss attempting to balance medical management of Lynch syndrome with their reproductive choices. Finally, they believe that increased awareness by women and their providers about the gynecologic cancer risks associated with Lynch syndrome should be a higher priority. We view the words of these women as a call to action for Lynch syndrome patients, clinicians, researchers, and advocates.

Germline gene polymorphisms predisposing domestic mammals to carcinogenesis

Cancer is a complex disease caused in part by predisposing germline gene polymorphisms. Knowledge of carcinogenesis in companion mammals (dog and cat) and some livestock species (pig and horse) is quite advanced. The prevalence of certain cancers varies by breed in these species, suggesting the presence of predisposing genetic variants in susceptible breeds. This review summarizes the present understanding of germline gene polymorphisms, including BRCA1, BRCA2, MC1R, KIT, NRAS and RAD51, associated with predisposition to melanoma, mammary cancer, osteosarcoma and histiocytic sarcoma in dogs, cats, pigs and horses. The predisposing variants in these species are discussed in the context of human germline gene polymorphisms associated with the same types of cancer.

Milestones of Lynch syndrome: 1895-2015

Lynch syndrome, which is now recognized as the most common hereditary colorectal cancer condition, is characterized by the predisposition to a spectrum of cancers, primarily colorectal cancer and endometrial cancer. We chronicle over a century of discoveries that revolutionized the diagnosis and clinical management of Lynch syndrome, beginning in 1895 with Warthin's observations of familial cancer clusters, through the clinical era led by Lynch and the genetic era heralded by the discovery of causative mutations in mismatch repair (MMR) genes, to ongoing challenges.

Communication and technology in genetic counseling for familial cancer

When a cancer predisposing germline mutation is detected in an index case, the presence of the underlying syndrome is confirmed and the potential for predictive testing of at-risk relatives is established. However, the reporting of a positive family history does not routinely lead to communication of information about risk to close, much less distant relatives. This review summarizes information technology utilized to address penetration or 'reach' of knowledge of risk within extended families, including the use of telephone and video counseling to reach distant patients, and anticipate novel internet-based processes for communication between investigators and relatives.

Clinical utility of family history for cancer screening and referral in primary care: a report from the Family Healthware Impact Trial

PURPOSE

To assess the effectiveness of computerized familial risk assessment and tailored messages for identifying individuals for targeted cancer prevention strategies and motivating behavior change.

METHODS

We conducted a randomized clinical trial in primary care patients aged 35-65 years using Family Healthware, a self-administered, internet-based tool that collects family history for six common diseases including breast cancer, colon cancer, and ovarian cancer, stratifies risk into three tiers, and provides tailored prevention messages. Cancer screening adherence and consultation were measured at baseline and 6-month follow-up.

RESULTS

Of 3283 participants, 34% were at strong or moderate risk of at least one of the cancers. Family Healthware identified additional participants for whom earlier screening (colon cancer, 4.4%; breast cancer, women ages: 35-39 years, 9%) or genetic assessment (colon cancer, 2.5%; breast cancer, 10%; and ovarian cancer, 4%) may be indicated. Fewer than half were already adherent with risk-based screening. Screening adherence improved for all risk categories with no difference between intervention and control groups. Consultation with specialists did not differ between groups.

CONCLUSION

Family Healthware identified patients for intensified cancer prevention. Engagement of clinicians and patients, integration with clinical decision support, and inclusion of nonfamilial risk factors may be necessary to achieve the full potential of computerized risk assessment.

Hereditary gastrointestinal cancer syndromes

The rapid growth of molecular genetics and its attendant germline mutation discoveries has enabled identification of persons who are at an inordinately high cancer risk and, therefore, ideal candidates for prevention. However, one must fully appreciate the extensive genotypic and phenotypic heterogeneity that exists in hereditary cancer. Once the causative germline mutation has been identified in a patient, high-risk members of the family can be similarly tested and identified and provided highly targeted surveillance and management opportunities. DNA testing can change the individual's presumed risk status and affect decision making by patients and their physicians regarding surveillance and management. Our purpose is to describe familial/hereditary cancers of the gastrointestinal tract, including familial Barrett's esophagus, hereditary diffuse gastric cancer, gastrointestinal stromal tumors, familial adenomatous polyposis and desmoid tumors, Lynch syndrome, small bowel cancer, and familial pancreatic cancer. We use our discussion of Lynch syndrome as a model for diagnostic and clinical translation strategies for all hereditary gastrointestinal tract cancers, which clearly can then be extended to cancer of all anatomic sites. Highly pertinent questions from the patient's perspective include the following: What kind of counseling will be provided to a patient with a Lynch syndrome mutation, and should that counseling be mandatory? Does the proband have the responsibility to inform relatives about the familial mutation, even if the relatives do not want to know whether they carry it? Is the patient is responsible for notifying family members that a parent or sibling has Lynch syndrome? Can notification be forced and, if so, under what circumstances? These questions point out the need for criteria regarding which family members to inform and how to inform them.

Making sense of missense in Lynch syndrome: the clinical perspective

The DNA mismatch repair (MMR) system provides critical genetic housekeeping, and its failure is associated with tumorigenesis. Through distinct domains on the DNA MMR proteins, the system recognizes and repairs errors occurring during DNA synthesis, but signals apoptosis when the DNA damage cannot be repaired. Certain missense mutations in the MMR genes can selectively alter just one of these functions. This affects the clinical features of tumors associated with defective DNA MMR activity. New work reported by Xie et al. in this issue of the journal (beginning on page 1409) adds to the understanding of DNA MMR.

Managing hereditary gastrointestinal cancer syndromes: the partnership between genetic counselors and gastroenterologists

A standard of care for the recognition and management of patients and families with hereditary gastrointestinal cancer syndromes is emerging, and both gastroenterologists and genetic counselors have an important role. This Review considers these roles and outlines the partnership needed between gastroenterologists and genetic counselors. The role of the gastroenterologist involves careful sampling of polyps and tumors, and requires a basic working knowledge of the features of hereditary gastrointestinal cancer syndromes. The role of the genetic counselor is to gather and synthesize family history and pathology information, formulate a genetic differential diagnosis, determine a genetic testing strategy, guide medical management and help patients communicate information to their relatives. Managing the complex logistics of testing the best candidate in the family, facilitating informed consent, outlining costs to patients and interpreting test results are also responsibilities assumed by genetic counselors. In addition, genetic counselors help physicians meet their ethical and medicolegal obligations with respect to patient management and family communication. Referral schemata for patients with polyposis and nonpolyposis features are presented in this Review, along with comprehensive tables that outline the features of well-known and rare syndromes that heighten the risk of gastrointestinal malignancy.

Accurate classification of MLH1/MSH2 missense variants with multivariate analysis of protein polymorphisms-mismatch repair (MAPP-MMR)

Lynch syndrome, also known as hereditary nonpolyposis colon cancer (HNPCC), is the most common known genetic syndrome for colorectal cancer (CRC). MLH1/MSH2 mutations underlie approximately 90% of Lynch syndrome families. A total of 24% of these mutations are missense. Interpreting missense variation is extremely challenging. We have therefore developed multivariate analysis of protein polymorphisms-mismatch repair (MAPP-MMR), a bioinformatic algorithm that effectively classifies MLH1/MSH2 deleterious and neutral missense variants. We compiled a large database (n>300) of MLH1/MSH2 missense variants with associated clinical and molecular characteristics. We divided this database into nonoverlapping training and validation sets and tested MAPP-MMR. MAPP-MMR significantly outperformed other missense variant classification algorithms (sensitivity, 94%; specificity, 96%; positive predictive value [PPV] 98%; negative predictive value [NPV], 89%), such as SIFT and PolyPhen. MAPP-MMR is an effective bioinformatic tool for missense variant interpretation that accurately distinguishes MLH1/MSH2 deleterious variants from neutral variants.

Hereditary colorectal cancer syndromes: molecular genetics, genetic counseling, diagnosis and management

Hereditary forms of colorectal cancer, as is the case with virtually all forms of hereditary cancer, show extensive phenotypic and genotypic heterogeneity, a phenomenon discussed throughout this special issue of Familial Cancer. Clearly, the family physician, oncology specialist, genetic counselor, and cancer geneticist must know fully the complexity of hereditary cancer syndromes, their differential diagnosis, in order to establish a diagnosis, direct highly-targeted surveillance and management, and then be able to communicate effectively with the molecular geneticist so that an at-risk patient's DNA can be tested in accord with the syndrome of concern. Thus, a family with features of the Lynch syndrome will merit microsatellite instability testing, consideration for immunohistochemistry evaluation, and mismatch repair gene testing, while, in contrast, a patient with FAP will require APC testing. However, other germline mutations, yet to be identified, may be important should testing for these mutations prove to be absent and, therein, unrewarding to the patient. Nevertheless, our position is that if the patient's family history is consistent with one of these syndromes, but a mutation is not found in the family, we still recommend the same surveillance and management strategies for patients from families with an established cancer-causing germline mutation. Our purpose in this paper is to provide a concise coverage of the major hereditary colorectal cancer syndromes, to discuss genetic counseling, molecular genetic evaluation, highly targeted surveillance and management, so that cancer control can be maximized for these high hereditary cancer risk patients.

Gynecological tumors revealing hereditary nonpolyposis colorectal cancer: analysis of a large Lebanese pedigree

The objective of this study was to evaluate the aggregation of colorectal cancer (CRC) and hereditary nonpolyposis colorectal cancer (HNPCC)-related extracolonic cancers in an extended Lebanese family with HNPCC. This was a pedigree analysis and a prospective follow-up over an 8-year period. The causative germ line mutation was detected using denaturing high-performance liquid chromatography, polymerase chain reaction (PCR) of short fluorescent fragments, and direct DNA sequencing of purified PCR products. The penetrance of CRC is high and accounts for approximately two thirds of risk carriers with an early age of onset (21 years). The extracolonic cancer spectrum includes ovary, endometrium, small bowel, skin, and brain, with an age of onset as early as 30 years. The causative mismatch repair gene mutation is an MSH2 point mutation involving the splice donor site of intron 3 (G-->A). Scrutinized in genomic DNA from 35 consented members, it was found in 18 of them and cosegregates with the cancer phenotype in the family. Early-onset ovarian and endometrial carcinomas may reveal HNPCC families in the Middle Eastern region, with MSH2 germ line mutation. We propose a biannual screening program, starting around the age of 20-25 years, pending additional data on this topic.

Screening and preventive behaviors one year after predictive genetic testing for hereditary nonpolyposis colorectal carcinoma

BACKGROUND

Prevention benefits from predictive genetic testing for cancer will only be fully realized if appropriate screening is adopted after testing. The current study assessed screening and preventive behaviors during 12 months after predictive genetic testing for hereditary nonpolyposis colorectal carcinoma (HNPCC) in an Australian clinical cohort.

METHODS

Participants received predictive genetic testing for HNPCC at one of five Australian familial cancer clinics. Data on self-reported screening behaviors (colonoscopy, and endometrial sampling and transvaginal ultrasound for women) and prophylactic surgery (colectomy, and hysterectomy and bilateral oophorectomy for women) were collected using postal questionnaires before (baseline) and 12 months after receipt of genetic test results. Age, gender, perceived risk of cancer, and cancer-specific distress were assessed as predictors of colonoscopic screening.

RESULTS

In the current study, 114 participants returned baseline questionnaires (32 carriers and 82 noncarriers of an HNPCC mutation). Ninety-eight participants also returned a 12-month follow-up questionnaire. Of those > or = 25 years, 73% reported having had a colonoscopy before genetic testing. At follow-up, 71% (15 of 25) of carriers and 12% (8 of 65) of noncarriers reported having a colonoscopy in the 12 months after receipt of test results. The reduction in colonoscopy among noncarriers was statistically significant (P < 0.001). High perceived risk was associated with colonoscopy at baseline. At follow-up, mutation status was the only variable significantly associated with colonoscopy. Among female mutation carriers, 47% reported having transvaginal ultrasonography and 53% endometrial sampling during follow-up. There was low uptake of prophylactic surgery for colorectal, endometrial, or ovarian carcinomas.

CONCLUSIONS

The majority of individuals reported appropriate screening behaviors after predictive genetic testing for HNPCC. The small group of noncarriers who had screening after genetic testing might benefit from additional counseling.

Clinical phenotype and prevalence of hereditary nonpolyposis colorectal cancer syndrome in Chinese population

AIM: To describe systematically the clinical characteristics and phenotype of HNPCC families and the prevalence of HNPCC in the general population of CRC patients in China.

METHODS: HNPCC kindreds and CRC patients were from two sources. One was that we consecutively investigated kindreds and patients by ourselves. And the other was the published Chinese and foreign literature related to Chinese HNPCC syndrome. There were 142 HNPCC families fulfilling AC I and/or AC II including 57 families with detailed data, and 3874 general primary CRC patients in all. All statistical tests were two-sided.

RESULTS: In AC I families, the number of Lynch syndrome I and II families were 25 (47.2%) and 28 (52.8%) respectively. There were 215 patients (82.4%) with CRC, 67 patients (25.7%) with extracolonic cancer and 50 patients (19.2%) with multiple primary cancers. In all CRC patients, multiple primary CRC were in 41 patients (19.1%), and the first-CRC was right-sided colorectal cancer in 143 patients (66.5%) and rectal cancer in 44 patients (20.5%). 8.8% and 19.2% of the first cancer were CRC and extracolonic cancers. Among those patients whose first cancer was CRC, 66.8% and 19.9% were right-sided colorectal cancer and rectal cancer, respectively. The similar results were found in AC II families. Normal distribution was only found in the distribution of the age of diagnosis of the first cancer in both AC I families (coefficient of skewness: u = 0.81, 0.20<0.40<P<0.50; coefficient of kurtosis: u = 1.13, 0.20<P<0.40, α = 0.20) and AC II families (coefficient of skewness: u = 0.63, P>0.5>0.20; coefficient of kurtosis: u = 0.84, 0.20<0.40<P<0.50, α = 0.20), but not found in the distribution of the age of diagnosis of the first CRC. When patients with HNPCC-associated cancer suffered from the first malignant tumor in HNPCC families diagnosed by AC I and AC II, the mean age and median age were 45.1±12.7 years and 44.0 years, 45.2±12.7 years and 44.5 years, respectively. The median age of diagnosis of the first tumor of the patients in the later generation was younger than that in the previous generation. Many extracolonic cancers were found to be associated with HNPCC syndrome. Gastric cancer was the most frequent extracolonic cancer followed by endometrial cancer and hepatocarcinoma. In general population of CRC patients, the prevalence of HNPCC diagnosed by AC I and AC II were 1.3% and 2.2%, respectively.

CONCLUSION: The clinical phenotype and prevalence of Chinese HNPCC syndrome are similar to those of Europeans and Americans. Gastric cancer is the most common extracolonic malignant tumor. The age of diagnosis of the first malignant tumor tends to be increasingly younger in patients with HNPCC-related tumors.

Genetic detection of Chinese hereditary nonpolyposis colorectal cancer

AIM: To explore the germline mutations of the two main DNA mismatch repair genes (hMSH2 and hMLH1) between patients with hereditary non-polyposis colorectal cancer (HNPCC) and suspected (atypical) HNPCC.

METHODS: Genomic DNA was extracted from the peripheral blood of the index patient of each family, and germline mutations of hMSH2 and hMLH1 genes were detected by PCR-single strand conformation polymorphism (PCR-SSCP) and DNA sequencing techniques.

RESULTS: For PCR-SSCP analysis, 67% (4/6) abnormal exons mobility in typical group and 33% (2/6) abnormal exons mobility in atypical group were recognized. In direct DNA sequencing, 50% (3/6) mutation of MMR genes in typical group and 33% (2/6) mutation of MMR genes in atypical group were found, and 4/6 (66.67%) and 1/6 (16.67%) mutations of hMSH2 and hMLH1 were identified in typical HNPCC and atypical HNPCC, respectively.

CONCLUSION: Mutation detection of the patients is of benefit to the analysis of HNPCC and, PCR-SSCP is an effective strategy to detect the mutations of HNPCC equivalent to direct DNA sequence. It seems that there exist more complicated genetic alterations in Chinese HNPCC patients than in Western countries.