Current approaches in familial colorectal cancer: a clinical perspective

Individuals with a family history of colorectal cancer or colorectal adenomas have an increased risk for colorectal cancer. When no hereditary syndrome is evident, screening is based on empiric risk estimates. The risk is greatest for individuals with specific inherited cancer-predisposing disorders. When conditions such as familial adenomatous polyposis or hereditary nonpolyposis colorectal cancer are diagnosed, specific neoplasm risk estimates can usually be performed based on advances in molecular genetics. These estimates lead to more straightforward and cost-effective approaches to surveillance and management. The National Comprehensive Cancer Center Network (NCCN) and other groups have provided detailed guidelines for evaluating patients based on recognition of clinical syndrome characteristics, followed by appropriate genetic counseling, genetic testing, and optimal surveillance. The NCCN guidelines are used as a frame of reference for this discussion of selected recent advances in human cancer genetics as they apply to clinical practice.     

Factors affecting encouragement of relatives among families with Lynch syndrome to seek medical assessment

Lynch syndrome (HNPCC) is an autosomal dominant hereditary cancer syndrome, and members of affected families are at-risk for developing colorectal and other associated tumors. Such individuals should disseminate familial genetic information, so they can seek specific medical assessment or genetic testing to reduce mortality and morbidity rates by early detection. Since published results have been encouraging, we explored which factors influence the likelihood of good communication within families regarding medical assessment. We studied 40 individuals from 33 families who satisfied the Japanese clinical criteria for Lynch syndrome and their relatives at our hospital. We determined the status of relatives of the 40 individuals after genetic counseling and testing using questionnaires and semi-structured interviews based on pedigree charts. We also examined their knowledge or perception of colorectal cancer syndrome, levels of intimacy and whether or not they encouraged their relatives to have specific medical assessments. We found that 75% of the individuals advised their relatives to seek medical assessment, and any significant background factors that promoted such encouragement were observed. They tended to encourage first degree relatives and discuss the issue with other family members such as spouses before undertaking such attempts at encouragement. The reasons and methods of imparting encouragement were essentially identical. We also found that genetic testing for at-risk or more distant relatives was not encouraged so often. Therefore, providing individuals who have been tested for Lynch syndrome with opportunities for disseminating familial genetic information through appropriate genetic counseling is important.     

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.     

Current status of genetic testing for colorectal cancer susceptibility

Over 130,000 new cases of colon cancer are diagnosed annually. Approximately 20% to 30% of these are attributable to familial risk, and 3% to 5% belong to a hereditary colorectal cancer predisposition syndrome. Recent discoveries of the genes responsiblefor the inherited colorectal cancer conditions have expanded the field of commercial genetic testing. Health-care providers who use genetic testing in clinical practice are aware of the benefits that genetic testing can confer on screening, prevention, and treatment options for patients with a personal and/or family history of colon cancer. When genetic test results are correctly interpreted, the information they provide can offer medical guidance for the entire family. The psychological impact, however, of presymptomatic testing can be multifaceted. There are unprecedented benefits but also complex issues surrounding genetic testing. For these reasons, the practice of offering genetic testing to individuals at high risk for colon cancer is heavily fortified with guidelines and recommendations. This review covers the current availability and limitations of genetic testing for inherited colorectal cancer syndromes and focuses on guidelines that address the psychological, ethical, and social concerns stemming from genetic testing.     

Genetic counseling and clinical cancer genetics services

Cancer genetic services, typically provided by clinicians with expertise in both oncology and genetics, include cancer risk assessment and education, facilitation of genetic testing, pre-and post-test counseling, provision of personally tailored cancer risk management options and recommendations, and psychosocial counseling and support services. All oncology providers should obtain basic information on the family cancer history of their patients to determine the likelihood of hereditary cancer risk as well as possible indications for providing brief or comprehensive cancer genetic counseling. Those who choose to provide these services themselves must be familiar with the complex issues of genetic counseling and testing, and be aware of the time and expertise required to adequately deliver these services. Genetic nurses and genetic counselors with master's degrees function as valuable members of a comprehensive cancer genetic service; they are trained to independently collect and confirm medical and family history information, perform risk assessments, offer patient education regarding cancer and genetics, and provide supportive counseling services for patients and families. It is hoped that specific risk interventions will significantly reduce morbidity and mortality from familial forms of cancer. This review outlines the process of cancer genetic counseling and defines the roles of the cancer genetic counselor and the function of the cancer genetics specialty clinic. The possible medical and legal implications for failing to obtain adequate family history information are reviewed, and the issues of genetic discrimination are discussed.     

Hereditary nonpolyposis colorectal cancer: preventive management

Hereditary nonpolyposis colorectal cancer (HNPCC) is the most common form of hereditary colorectal cancer. Inherited mutations in the mismatch repair genes associated with this syndrome have an approximate 80% lifetime risk of colorectal cancer. Since there are no premonitory signs of susceptibility to HNPCC, family history is the initial method for identifying those at increased risk. At risk individuals should undergo genetic counseling and testing. Although an algorithmic indication for genetic testing in at risk HNPCC patients is yet to be determined, many advocate initial screening for microsatellite instability (MSI) of the cancer specimen in individuals suspected of carrying HNPCC mutations. Those who test positive for MSI can then undergo further testing for mutations in the associated germline mismatch repair genes. Techniques for detecting these mutations currently include in vitro synthesized-protein assay, single-strand conformational polymorphism, and DNA sequencing. Given the aggressive nature of HNPCC adenomas, individuals who test positive for HNPCC mutations are recommended to undergo yearly colonoscopic surveillance starting at the age of 25. A reasonable alternative to lifetime colonoscopic surveillance for the prevention of colorectal cancer in these individuals is prophylactic colectomy. The prevention of colorectal cancer through pharmacological means is under investigation as another option in the management of HNPCC patients. Specifically, chemoprevention trials are currently ongoing to evaluate the efficacy of COX-2 inhibitors in the prevention of colorectal cancer in HNPCC and familial adenomatous polyposis patients.     

Cancer screening and genetic counseling

Familial predisposition to cancer has been recognized for many years. The discovery fifteen years ago of some of the genes that are involved in the heritance of very common malignant diseases, like breast and colorectal cancer, has represented a major advance, and a challenge, for cancer prevention. Colorectal cancer is the first incident malignancy in our population, and breast cancer can affect 1 in 12 women in some European countries. There are several models that calculate the risk of cancer based on personal conditions or familial history. Testing for genes related to hereditary cancer allows the selection of individuals who will really benefit of prevention measures in such high prevalent diseases. The majority of these genes belong to the category of tumor suppressor genes, a second genetic hit is always needed for tumor developing. Epigenetics, defined as the factors that modulate the penetrance of a genetic disease, play an important role in hereditary cancer predisposition. Due to the complexity of genetics and clinical management of the hereditary cancers, all individuals with risk should be seen at Cancer Genetic Counseling units or Cancer Family Clinics. The clinicians that work in these Units should have special training in genetic counseling, cancer genetics and hereditary cancer management. Cancer Genetic Counseling is a communication process in which genetics, medical and psychological issues related to hereditary cancer risk development and prevention options are discussed with the individuals and families. Counseling must not be biased, and individual autonomy must be protected. A collaborative model between counselor and patient is preferred, and all the following points should be included in the informed consent process: options for risk estimation if genetic testing is not done,information on the specific test (accuracy, limitations), interpretation of all possible test results, implications of results for the individual and family, confidentiality issues, risk of psychological distress, options for care after testing and limitations. Some ethical and legal issues arise in the global processes of cancer genetic counseling that must be recognized and taken in account. Many questions have still not answers in this field. Nonetheless, it would be inappropiate to dismiss the potential benefits of genetic counseling as a reaction to sporadic uncritical application of genetic testing. This paper will review the genetic basis and the opportunity for screening and prevention of the hereditary predisposition to cancer, mainly focused to breast, ovarian and colorectal cancer.     

Cancer screening guidelines and prevention factors for high-risk patients with a family history of colorectal cancer

Family history of colorectal cancer or of adenomas may confer significant risk of colorectal cancer. Ideally, diagnosis of an inherited syndrome such as familial adenomatous polyposis (FAP) or hereditary nonpolyposis colorectal cancer (HNPCC) enables a molecular biology-driven approach to screening and management. When no hereditary syndrome can be established, clinicians must rely on empiric risk estimates and offer screening accordingly. Detailed rationale and guidelines for use of syndrome characteristics including genetic testing, counseling, and selection of surveillance tools are discussed.     

Hereditary nonpolyposis colorectal cancer

Hereditary nonpolyposis colorectal cancer (HNPCC), or Lynch syndrome, is the most common form of hereditary colorectal cancer (CRC). A well-orchestrated cancer family history is essential for its diagnosis since, unlike its familial adenomatous polyposis (FAP) hereditary cancer counterpart, HNPCC lacks distinguishing clinical stigmata of its cancer genetic risk. Discoveries in the 1990s of germ-line mutations, the most common of which are hMSH2 and hMLH1, have added enormous power to the diagnosis of Lynch syndrome. Its medical management is contingent upon its natural history. For example, approximately 70% of CRCs occur proximal to the splenic flexure, with one-third of the cancers occurring in the cecum, thereby mandating full colonoscopy. A high rate of metachronous CRCs indicates the need for no less than a subtotal colectomy for the management of initial CRC. Genetic counseling is essential prior to DNA testing, and at the time of disclosure of the results. Education of patients as well as physicians about all facets of this disorder is extremely important. If patients are to show compliance with germ-line testing, screening, and management options, they must understand the natural history and the significance of their genetic risk status. Physicians must also be aware of clinical nuances of this disorder to provide the necessary care.     

Genetic counseling and cascade genetic testing in Lynch syndrome

Lynch syndrome is the most common cause of inherited colorectal and endometrial cancers. Individuals with Lynch syndrome have a 10–80 % lifetime risk for colorectal cancer and a 15–60 % lifetime risk for endometrial cancer. Both cancers are preventable through chemoprevention, intensive cancer surveillance, and risk-reducing surgery options. Efforts to identify as many individuals with Lynch syndrome as possible will prevent cancers and save lives. This includes the traditional cancer genetic counseling model whereby individuals with and without cancer are evaluated for a possible Lynch syndrome diagnosis based on their personal and family history of colon polyps and cancers. It also includes universal tumor screening for Lynch syndrome whereby all individuals with colorectal or endometrial cancer are screened for tumor features of Lynch syndrome at the time of diagnosis. Those with tumors suspicious for Lynch syndrome are referred for cancer genetic counseling regardless of their family history of cancer. This two approaches must be maximized to attain high patient reach. Finally, and perhaps most importantly, cascade testing among the at-risk relatives of those diagnosed with Lynch syndrome is critically important to maximize the diagnosis of individuals with Lynch syndrome. In fact, the cost-effectiveness of universal tumor screening for Lynch syndrome relies entirely on counseling and testing as many at-risk individuals as possible since young unaffected individuals stand to benefit the most from an early diagnosis of Lynch syndrome. This approach must be optimized to achieve high family reach. It will take a concerted effort from patients, clinicians and public health officials to improve current approaches to the diagnosis of Lynch syndrome and the prevention and treatment of Lynch syndrome-associated cancer but these lessons can be applied to other conditions as the ultimate example of personalized medicine.     

Familial colorectal cancer: Patient assessment,surveillance and surgical management

Germline mutations account for 5–10% of colorectal cancer. Most mutations are autosomal dominant with high penetrance and affected patients benefit greatly from appropriate treatment. This review presents the current knowledge regarding familial colorectal cancer and provides practical information based on international guidelines and the best available evidence regarding patient assessment, surveillance and surgical management.Surgeons are often the first point of contact and frequently, the main provider of care for families with cancer syndromes or patients with familial cancer. Patients with a polyposis phenotype should undergo appropriate genetic testing. In non-polyposis patients with a cancer diagnosis, tumor testing for Lynch syndrome can guide the use of genetic testing. In patients without a personal history of cancer or polyposis, a carefully obtained family history with testing of available tumor tissue or of a living relative affected by colorectal cancer informs the need for genetic testing. Surveillance and surgical management should be planned following thorough assessment of familial cancer risk.Evidence exists to provide guidance as to the surveillance strategies required, the specific indications of genetic testing and the appropriate timing of operative intervention. A carefully obtained family history with selective genetic testing should inform surveillance and surgical management in patients who have a genetic predisposition for the development of colorectal cancer.     

Genetic diagnosis of Lynch syndrome II in an extended colorectal cancer-prone family

Knowledge of colon cancer genetics, with particular attention to precision in hereditary cancer syndrome diagnosis, can often enable highly targeted surveillance and management strategies for patients at high genetic risk. Unfortunately, the patient's family history of cancer is often given minimal attention, and knowledge of hereditary cancer syndromes is frequently limited. Indeed, many physicians still consider familial adenomatous polyposis (FAP) as the only genetic risk factor for colorectal cancer. This concern with FAP was noted in a colorectal cancer-prone kindred which for decades had been thought to manifest that syndrome. However, after meticulous genetic, medical, and pathologic studies, the cardinal phenotypic characteristics of Lynch syndrome II were observed. The potential for cancer control in current and future generations of families like this one clearly mandates the need for computerized registries which could transmit current information about hereditary colon cancer syndrome diagnosis, surveillance, and management.     

Genetic counseling and predictive testing for colorectal cancer risk

In contrast to our rapidly increasing knowledge of the genetic basis of colorectal cancer and new molecular technologies, we are only in the early stages of characterizing the impact that this information will have on patients, their families and society. From our research and clinical experience with hereditary colorectal cancer syndromes, we have developed a framework for risk assessment that includes criteria for identifying those at higher genetic risk and guidelines for genetic counseling, predictive genetic testing and follow-up management. More research is needed to optimally translate this framework into wider clinical practice, including characterizing genetic heterogeneity and phenotype correlations, documenting the efficacy of screening and surgical interventions, and maximizing the awareness of health professionals on genetic counseling and the promise and limitations of gene tests. © 1996 Wiley-Liss, Inc.     

Basic concepts for genetic testing in common hereditary colorectal cancer syndromes

Approximately 5% of colorectal cancers are associated with an autosomal dominantly inherited colon cancer syndrome. The two most common familial colon cancer syndromes are hereditary nonpolyposis colorectal cancer (HNPCC), also called Lynch syndrome, and familial adenomatous polyposis (FAP). In many families with these syndromes, the causative mutation can be identified by genetic testing of an affected individual. If an affected individual tests positive for a disease-causing mutation, unaffected, at-risk family members can have genetic testing to determine whether they have inherited the cancer susceptibility mutation, and a personalized cancer surveillance strategy can be adopted. Genetic testing greatly enhances cancer risk assessment in these families; however, the complicated nature of interpretation of the results of gene testing and the emotional impact of the result require that testing be carried out in conjunction with patient education and informed consent by a provider who has a good appreciation for the challenges. This article describes the genetic testing strategy in HNPCC and FAP.     

Hereditary breast-ovarian cancer at the bedside: role of the medical oncologist.

PURPOSE: To provide practical considerations for diagnosing, counseling, and managing patients at high risk for hereditary breast cancer. DESIGN: We have studied 98 extended hereditary breast cancer (HBC)/hereditary breast-ovarian cancer (HBOC) families with BRCA1/2 germline mutations. From these families, 1,315 individuals were counseled and sampled for DNA testing. Herein, 716 of these individuals received their DNA test results in concert with genetic counseling. Several challenging pedigrees were selected from Creighton University's hereditary cancer family registry, as well as one family from Evanston/Northwestern Healthcare, to be discussed in this present report. RESULTS: Many obstacles were identified in diagnosis, counseling, and managing patients at high risk for HBC/HBOC. These obstacles were early noncancer death of key relatives, perception of insurance or employment discrimination, fear, anxiety, apprehension, reduced gene penetrance, and poor compliance. Other important issues such as physician culpability and malpractice implications for failure to collect or act on the cancer family history were identified. CONCLUSION: When clinical gene testing emerged for BRCA1 and BRCA2, little was known about the efficacy of medical interventions. Potential barriers to uptake of testing were largely unexplored. Identification and referral of high-risk patients and families to genetic counseling can greatly enhance the care of the population at the highest risk for cancer. However, because premonitory physical stigmata are absent in most of these syndromes, an HBOC diagnosis may be missed unless a careful family history of cancer of the breast, ovary, or several integrally associated cancers is obtained.     

Comprehensive genetics clinic for familial tumors: proposal for a suitable system in Japan

With the progress of the Human Genome Project, genetic testing has become widely available and useful in several kinds of familial cancer. As the results of the genetic testing may predict future onset of the disease and/or may influence other family members, clinical oncologists have to consider the psychological challenges and ethical complexities of communicating hereditary cancer risk information to families. A clinical genetics approach, including genetic counseling, is fundamental before and after the genetic testing. We introduce our activity at the Division of Clinical and Molecular Genetics, Shinshu University Hospital. Our system of a multidisciplinary approach to genetic counseling could be suitable for other hospitals in Japan.     

Genetic testing in prostate cancer management: Considerations informing primary care

Inherited genetic mutations can significantly increase the risk for prostate cancer (PC), may be associated with aggressive disease and poorer outcomes, and can have hereditary cancer implications for men and their families. Germline genetic testing (hereditary cancer genetic testing) is now strongly recommended for patients with advanced/metastatic PC, particularly given the impact on targeted therapy selection or clinical trial options, with expanded National Comprehensive Cancer Network guidelines and endorsement from multiple professional societies. Furthermore, National Comprehensive Cancer Network guidelines recommend genetic testing for men with PC across the stage and risk spectrum and for unaffected men at high risk for PC based on family history to identify hereditary cancer risk. Primary care is a critical field in which providers evaluate men at an elevated risk for PC, men living with PC, and PC survivors for whom germline testing may be indicated. Therefore, there is a critical need to engage and educate primary care providers regarding the role of genetic testing and the impact of results on PC screening, treatment, and cascade testing for family members of affected men. This review highlights key aspects of genetic testing in PC, the role of clinicians, with a focus on primary care, the importance of obtaining a comprehensive family history, current germline testing guidelines, and the impact on precision PC care. With emerging evidence and guidelines, clinical pathways are needed to facilitate integrated genetic education, testing, and counseling services in appropriately selected patients. There is also a need for providers to understand the field of genetic counseling and how best to collaborate to enhance multidisciplinary patient care.     

Recognition and management of hereditary breast cancer syndromes

Clinicians should recognize the genetic syndromes that predispose to the development of breast cancer so that patients may be afforded the opportunity to have genetic testing to assist them and their family members in making medical management decisions. Approximately 80%-90% of hereditary breast cancer cases are caused by mutations in the BRCA1 and BRCA2 genes. Other important clinical genetic predispositions include Cowden syndrome, Li-Fraumeni syndrome, Peutz-Jeghers syndrome, and ataxia-telangiectasia. The key to identifying women who are at risk for a hereditary breast cancer lies in obtaining an adequate, three-generation family history, including ethnic background. For unaffected women, breast cancer risks can be estimated using the quantitative models of Gail and Claus, but there are limitations to these models. Other quantitative models predict the likelihood that a patient is carrying a mutated gene. Genetic testing is available at selected laboratories for each of the hereditary syndromes described, and there are three possible outcomes to testing. These outcomes and their management implications are described in detail. Clinical management options for women at high risk for breast cancer include surveillance, chemoprevention, and prophylactic surgery. Application of these principles can reduce morbidity in women with genetic predispositions to breast cancer.     

Real world experience with cancer genetic counseling via telephone

One barrier to genetic testing is the lack of access to genetic counselors. We provided cancer genetic counseling via telephone, through a pilot project for employees of a national health insurer, Aetna, Inc. Knowledge transfer, behavioral intentions, and patient satisfaction were assessed by survey after genetic counseling. Aetna sent an individual email to its employees nationwide notifying them of the availability of a new telephone genetic counseling and testing program and providing a link to take a brief screening questionnaire to determine whether they may be at risk of hereditary cancer. Employees completing the questionnaire received immediate feedback regarding whether there appeared to be a risk of hereditary cancer. If so, they were invited to schedule a telephonic genetic counseling session. After the session, respondents completed an online survey. 397 individuals completed the questionnaire. 39 proceeded with telephone genetic counseling, and 22 completed the follow-up survey, including all 11 women with family history warranting genetic testing. One third reported prior discussion about inherited cancer risk with their primary care provider (PCP); 12% were referred to a geneticist; 20% had an accurate perception of their own cancer risk. After counseling, 94% reported understanding their risk for cancer and 87% were aware of available risk-reduction strategies. 87% of high-risk respondents intended to engage in risk-management interventions. 93% reported high satisfaction. 66% indicated they would not have pursued genetic counseling if it had not been available by phone. Results suggest telephone counseling is a viable option for increasing access to genetic experts. In this sample, telephone counseling increases knowledge of cancer risk, motivates intention to change health-related behaviors, and elicits a high satisfaction level. Consequently, Aetna now offers telephone cancer genetic counseling nationwide as a covered benefit.     

Diagnosing Lynch syndrome: more light at the end of the tunnel

Since the recognition of Lynch syndrome, which confers a high risk of colorectal, uterine, and other cancers, approaches to its diagnosis have included a family history of associated cancers and web-based algorithms. Identification of causative genes now allows a precise diagnosis, thus focusing present efforts on who should have genetic testing. Testing for cancer tissue changes can determine who should have germline genetic testing. Indeed, such tumor testing is now generally recommended for all newly diagnosed colorectal cancer cases. As reported in this issue of the journal by Yurgelun and colleagues (beginning on page 574), large colorectal adenomatous polyps (≥10 mm) from patients with Lynch syndrome exhibit findings similar to those in Lynch syndrome colorectal cancer tissues. This finding indicates that testing larger adenomas in persons at a significant risk for Lynch syndrome can now determine the need for germline genetic testing. Although further study is needed for general application, the present study justifies large polyp testing in high-risk families when cancer tissue is unavailable, albeit negative polyp tissue would not rule out Lynch syndrome, as would negative cancer tissue.