Suggested screening guidelines for familial colorectal cancer

Cascade screening in HBOC and Lynch syndrome: guidelines and procedures in a UK centre

In the 33 years since the first diagnostic cancer predisposition gene (CPG) tests in the Manchester Centre for Genomic Medicine, there has been substantial changes in the identification of index cases and cascade testing for at-risk family members. National guidelines in England and Wales are usually determined from the National Institute of healthcare Evidence and these have impacted on the thresholds for testing BRCA1/2 in Hereditary Breast Ovarian Cancer (HBOC) and in determining that all cases of colorectal and endometrial cancer should undergo screening for Lynch syndrome. Gaps for testing other CPGs relevant to HBOC have been filled by the UK Cancer Genetics Group and CanGene-CanVar project (web ref. https://www.cangene-canvaruk.org/ ). We present time trends (1990-2020) of identification of index cases with germline CPG variants and numbers of subsequent cascade tests, for BRCA1, BRCA2, and the Lynch genes (MLH1, MSH2, MSH6 and PMS2). For BRCA1/2 there was a definite increase in the proportion of index cases with ovarian cancer only and pre-symptomatic index tests both doubling from 16 to 32% and 3.2 to > 8% respectively. A mean of 1.73-1.74 additional family tests were generated for each BRCA1/2 index case within 2 years. Overall close to one positive cascade test was generated per index case resulting in > 1000 risk reducing surgery operations. In Lynch syndrome slightly more cascade tests were performed in the first two years potentially reflecting the increased actionability in males with 42.2% of pre-symptomatic tests in males compared to 25.8% in BRCA1/2 (p < 0.0001).

Colosigmoid junction: morphohistologic, morphometric, and endoscopic study with identification of colosigmoid canal with sphincter

To study the anatomical structure of the colosigmoid junction, 15 cadaveric specimens were studied morphologically, another 15 histologically, and a morphometric study was done in 10 specimens. Specimens consisted of the descending colon, sigmoid colon, and the colosigmoid junction. Histologic specimens were stained with hematoxylin and eosin and Masson's trichrome stain. Morphometric studies used an image analysis system. The colosigmoid junction was investigated endoscopically in 18 healthy volunteers. A narrow segment having a mean length of 5.2 +/- 1.1 cm was identified both externally and internally between the descending and sigmoid colon. We called this segment the colosigmoid canal. Mucosal folds were found crowded in the colosigmoid canal, the lower end of which formed a nipple and was surrounded by a fornix. Histologically, the colosigmoid canal mucosa showed multiple folds. Its circular muscle was thicker than that of the descending or the sigmoid colon and confirmed morphometrically. The longitudinal muscle was thicker in only 4 of 10 specimens. Both the narrowing and the mucosal crowding were verified endoscopically. The colosigmoid junction is the narrow segment between the descending and the sigmoid colon. Histologic, morphometric and endoscopic studies indicated the presence of a sphincter in the colosigmoid canal. A colosigmoid sphincter is suggested to control the passage of colonic contents from the descending colon to the colosigmoid canal as well as to prevent reflux of sigmoid contents into the descending colon.

Does a “one-stop” gynecology screening clinic for women in hereditary nonpolyposis colorectal cancer families have an impact on their psychological morbidity and perception of health?

Screening programs can reduce the burden of disease, however, they can be associated with raised levels of anxiety. The risk of endometrial and ovarian cancer is increased in hereditary nonpolyposis colorectal cancer (HNPCC). There is no prospective evidence to support screening for gynecological disease in HNPCC, however, current recommendations include the use of ultrasound and endometrial biopsy. This study assesses the impact of screening for gynecological cancer on self-reported symptoms of anxiety, depression, and perceptions of health. Women from HNPCC families attending gynecological screening (n= 26) completed the Hospital Anxiety and Depression Scale and the ShortForm36v2 questionnaires prior to screening with transvaginal ultrasound, outpatient/office hysteroscopy, endometrial biopsy, and ovarian tumor marker assessment (CA125). The same questionnaires were completed at 3 and 6 months following screening (15/26). Women in HNPCC families attending for gynecological screening did not have excess symptoms of anxiety or depression at baseline in subjective comparison to other populations. The process of screening and false positive screening results had no significant impact on symptoms of anxiety and depression or perceptions of health. We conclude that within the limitations of analysis in this small study group, screening for gynecological disease in HNPCC does not appear to be associated with any psychological morbidity.

Prevention of colorectal cancer by colonoscopic surveillance in individuals with a family history of colorectal cancer: 16 year, prospective, follow-up study

OBJECTIVE

To determine to what extent individuals with various family histories of colorectal cancer (from one to three or more affected first degree relatives) benefit from colonoscopic surveillance.

DESIGN

Prospective, observational study of high risk families, followed up over 16 years.

SETTING

Tertiary referral family cancer clinic in London.

PARTICIPANTS

1678 individuals from families registered with the clinic. Individuals were classified according to the strength of their family history: hereditary non-polyposis colorectal cancer (if they fulfilled the Amsterdam criteria), and one, two, or three affected first degree relatives (moderate risk).

INTERVENTIONS

Colonoscopy was initially offered at five year intervals or three year intervals if an adenoma was detected.

MAIN OUTCOME MEASURES

The incidence of adenomas with high risk pathological features or cancer. This was analysed by age, the extent of the family history, and findings on previous colonoscopies. The cohort was flagged for cancer and death. Incidence of colorectal cancer and mortality during over 15,000 person years of follow-up were compared with those expected in the absence of surveillance.

RESULTS

High risk adenomas and cancer were most common in families with hereditary non-polyposis colorectal cancer (on initial colonoscopy 5.7% and 0.9%, respectively). In the families with moderate risk, these findings were particularly uncommon under age 45 (1.1% and 0%) and on follow-up colonoscopy if advanced neoplasia was absent initially (1.7% and 0.1%). The incidence of colorectal cancer was substantially lower-80% in families with moderate risk (P = 0.00004), and 43% in families with hereditary non-polyposis colorectal cancer (P = 0.06)-than the expected incidence in the absence of surveillance when the family history was taken into account.

CONCLUSIONS

Colonoscopic surveillance reduces the risk of colorectal cancer in people with a strong family history. This study confirms that members of families with hereditary non-polyposis colorectal cancer require surveillance with short intervals. Individuals with a lesser family history may not require surveillance under age 45, and if advanced neoplasia is absent on initial colonoscopy, surveillance intervals may be lengthened. This would reduce the demand for colonoscopic surveillance.

Gynecologic screening in hereditary nonpolyposis colorectal cancer

OBJECTIVE

In hereditary nonpolyposis colorectal cancer (HNPCC), women with a mismatch repair (MMR) gene mutation have a cumulative lifetime risk of 25-50% for endometrial cancer and 8-12% for ovarian cancer. Therefore, female members of HNPCC families are offered an annual gynecologic and transvaginal ultrasound (TVU) examination and serum level CA 125 analysis. The aim of the present study was to evaluate our 10-year experience with this screening program.

METHODS

Women who are MMR gene mutation carriers or who fulfil the Amsterdam criteria were identified from our HNPCC database. Information concerning the screening program was retrospectively collected from patient files.

RESULTS

Forty-one women, 35 premenopausal and 6 postmenopausal, were enrolled in the program with a median follow-up of 5 years (range 5 months-11 years). In 197 patient years at risk, 17 of 179 TVUs gave reason for endometrial sampling. Three premalignant lesions, with complex atypical hyperplasia, were discovered. One interval endometrial cancer was detected as a result of clinical symptoms. No abnormal CA 125 levels were measured and no ovarian cancers were detected.

CONCLUSIONS

These results demonstrate that gynecologic screening allows the detection of premalignant lesions of the endometrium but also illustrate that recognition and reporting of clinical symptoms by the women themselves is of utmost importance.

Management of colorectal cancer

Colorectal cancer is the second most common cause of cancer death in the UK. Prompt investigation of suspicious symptoms is important, but there is increasing evidence that screening for the disease can produce significant reductions in mortality. High quality surgery is of paramount importance in achieving good outcomes, particularly in rectal cancer, but adjuvant radiotherapy and chemotherapy have important parts to play. The treatment of advanced disease is still essentially palliative, although surgery for limited hepatic metastases may be curative in a small proportion of patients.

A systematic review and meta-analysis of familial colorectal cancer risk

OBJECTIVE

The aim of this study was to identify published studies quantifying familial colorectal cancer (CRC) risks in first-degree relatives of CRC and colorectal adenoma (CRA) cases and, through a meta-analysis, obtain more precise estimates of familial risk according to the nature of the family history and type of neoplasm.

METHODS

Twenty-seven case-control and cohort studies were identified, which reported risks of CRC in relatives of CRC cases and nine, which reported the risk of CRC in relatives of CRA cases. Pooled estimates of risk for various categories of family history were obtained by calculating the weighted average of the log relative risk estimates from studies.

RESULTS

The pooled estimates of relative risk were as follows: a first-degree relative with CRC 2.25 (95% CI = 2.00-2.53), colon 2.42 (95% CI = 2.20-2.65), and rectal 1.89 (95% CI = 1.62-2.21) cancer; parent with CRC 2.26 (95% CI = 1.87-2.72); sibling with CRC 2.57 (95% CI = 2.19-3.02); more than one relative with CRC 4.25 (95% CI = 3.01-6.08); relative diagnosed with CRC before age 45, 3.87 (95% CI = 2.40-6.22); and a relative with CRA 1.99 (95% CI = 1.55-2.55).

CONCLUSIONS

Individuals with a family history of CRC and CRA have a significantly elevated risk of developing CRC compared with those without such a history. Risks are greatest for relatives of patients diagnosed young, those with two or more affected relatives, and relatives of patients with colonic cancers.

Review article: the prevention of colorectal cancer

Colorectal cancer is a leading cause of cancer mortality in the industrialized world. Survival remains poor because most cases are diagnosed at an advanced stage. It is a preventable disease as colorectal cancers usually develop slowly from an identifiable precursor lesion, the adenoma. The existing strategies for colorectal cancer prevention include dietary prevention, chemoprevention and endoscopic intervention. The exact relationship between diet, particularly fibre, and colorectal cancer remains unclear, with the most recent studies suggesting that dietary fibre may not decrease colorectal cancer risk as previously thought. Non-steroidal anti-inflammatory drugs have been shown to have a protective effect against colorectal cancer, but the adverse effect profile of the non COX-2 selective drugs, particularly the risk of gastrointestinal haemorrhage, precludes their widespread use. There is increasing evidence that colorectal cancer incidence and mortality can be decreased from endoscopic polypectomy and early detection of cancer. Faecal occult blood testing in the general population ('average-risk') has been shown in randomized trials to decrease mortality from colorectal cancer by 15--33%. Long-term results of randomized trials of the effectiveness of flexible sigmoidoscopy and colonoscopy screening in the general population are awaited. Targeting high risk individuals may also be an effective and efficient way to decrease the colorectal cancer burden. As many as 15--30% of colorectal cases may be due to hereditary factors. Individuals with one or two direct relatives affected are at moderate risk for colorectal cancer (empirical lifetime mortality from colorectal cancer approximately 10%) and approximately 2--3% of cases arise in individuals harbouring highly penetrant autosomal dominant mutations, which puts them at high-risk for colorectal cancer. Surveillance colonoscopy is offered to individuals at moderate and high risk for colorectal cancer.

Hereditary non-polyposis colorectal cancer: an updated review

INTRODUCTION

Colorectal cancer is the commonest cause of death due to malignancy in non-smokers in the western countries. The two main hereditary types of colorectal cancer are familial adenomatous polyposis (FAP) and hereditary non-polyposis colorectal cancer (HNPCC), constituting approximately 10% of all cases of colorectal cancer. The main aim of this review is to reappraise the current advances in the genetics and diagnosis of HNPCC.

METHODS

A Medline search was carried out to identify papers published from 1970 to 1999 on HNPCC. Embase and Cochrane databases were also searched. Reference lists of retrieved articles were carefully searched for additional articles.

RESULTS AND CONCLUSIONS

Recent technological advances in the genetics of HNPCC have refined the criteria for diagnosis and management of HNPCC, however current policies regarding the testing of pedigrees are not clearly established. We believe that with the rapid development in this area definitive clinical guidelines will need to be available in future for the management of HNPCC.

[Identification of 2 families with hereditary nonpolyposis colonic cancer (HNPCC) and the Amsterdam criteria. Relevance of the genealogic tree and follow-up]

Hereditary nonpolyposis colorectal cancer (HNPCC) diagnosis is based either on the so-called "Amsterdam 1 criteria" or "Amsterdam 2 criteria", which includes extracolonic neoplasms associated with Lynch II syndrome. Many families are suspected of having a hereditary predisposition to cancer and may benefit from close surveillance. We describe a family (family 1) with suspected HNPCC at the beginning who fulfilled the Amsterdam 1 criteria over the course of its follow-up. We also describe an Amsterdam 2 family (family 2) with a very young affected individual. Both of them received genetic counseling and screening recommendations. A total colonoscopy was done to an asymptomatic member of family 1 and he was diagnosed with an early-stage colon cancer. He underwent subtotal colectomy because of the high risk of metachronous lesion. Screening recommendations must be the same in Amsterdam 2 families as in Amsterdam 1. Both families show the importance of considering the family history when hereditary criteria are suspected.

Aspirin suppresses the mutator phenotype associated with hereditary nonpolyposis colorectal cancer by genetic selection

Nonsteroidal anti-inflammatory drugs (NSAIDs) are well-known cancer preventives, which have been largely attributed to their antiproliferative and apoptosis-inducing activities. In this study, we show that microsatellite instability (MSI) in colorectal cancer cells deficient for a subset of the human mismatch repair (MMR) genes (hMLH1, hMSH2, and hMSH6), is markedly reduced during exposure to aspirin or sulindac [or Clinoril, which is chemically related to indomethacin (Indocin)]. This effect was reversible, time and concentration dependent, and appeared independent of proliferation rate and cyclooxygenase function. In contrast, the MSI phenotype of a hPMS2-deficient endometrial cancer cell line was unaffected by aspirin/sulindac. We show that the MSI reduction in the susceptible MMR-deficient cells was confined to nonapoptotic cells, whereas apoptotic cells remained unstable and were eliminated from the growing population. These results suggest that aspirin/sulindac induces a genetic selection for microsatellite stability in a subset of MMR-deficient cells and may provide an effective prophylactic therapy for hereditary nonpolyposis colorectal cancer kindreds where alteration of the hMSH2 and hMLH1 genes are associated with the majority of cancer susceptibility cases.

Germline HNPCC gene variants have little influence on the risk for sporadic colorectal cancer

Hereditary non-polyposis colorectal cancer (HNPCC) is a syndrome of inherited bowel and other cancers that has been said to account for up to 15% of all colorectal carcinomas (CRCs). HNPCC can now be diagnosed at the molecular level by detecting germline mutations in genes involved in mismatch repair. A current problem is to determine the prevalence of HNPCC mutations in colon cancer patients with limited or no family history, especially in cases of early onset. We have identified 50 cases of non-polyposis colorectal cancer without a family history of CRC or any other HNPCC cancer, who presented under the age of 45 years. Germline HNPCC variants (at the hMSH2 or hMLH1 loci) were detected in a small minority of cases (6%). The variants that we have found may be new or low penetrance mutations, or even polymorphisms. It remains possible that some of our sample have an inherited predisposition to CRC that is not caused by HNPCC mutations or by known polyposis syndromes. Our data suggest that most HNPCC mutations occur in families and have high or moderate penetrance. New or low penetrance HNPCC mutations probably do not contribute significantly to the risk of colorectal cancer in the general population and probably account for much fewer than 15% of all CRCs. Our results question whether mass population genetic screening programmes are worthwhile for diseases such as HNPCC using current technology.