Hereditary cancer: guidelines in clinical practice. Breast and ovarian cancer genetics

A systematic review on the association between ovarian and prostate cancer with <I>BRCA1</I> and <I>BRCA2</I> gene

Background. BRCA1 and BRCA2 were discussed as the basis of inherited adenocarcinoma and breast and ovarian malignancy. Ovarian cancer is uncommon in women below 40 years of age, and prostate cancer mainly occurs in older men cause 90 % in those above sixty-fve.

Objective. The main objective of this paper is to investigate the relationship between ovarian and prostate cancer with the BRCA1 and BRCA2 genes.

Material and Methods. The ovarian and prostate cancer mechanism is discussed in detail, and their preventive measures with screening techniques are also demonstrated. This systematic review collected the related articles from online databases using the key terms ovarian cancer, prostate cancer, BRCA genes, mutation, polymorphism, carcinoma, sarcoma, and genetic association.

Results. Based on the obtained information, it is found that the BRCA genes are highly associated with prostate cancer in men, and in women, it is significantly linked with breast cancer than ovarian cancer.

Conclusion. Therefore, early diagnosis and genetic testing for BRCA1&BRCA2 genes in both men and women are necessary. In some cases, these genes might even cause different types of cancer like pancreatic cancers. Identifying individuals with tumour-HRD through mutations in the homologous repair pathway and determining this gene expression is essential to improve treatment techniques developed during the previous decade and rapidly make their way into clinical trials practice. However, the safe introduction of these medicines into everyday practice will require a thorough understanding of treatment targets and associated adverse effects. 

New variants in the BRCA1 gene in Buryat Mongol breast cancer patients: Report from two families

BACKGROUND

The BRCA1 mutations that are endemic to the Slavic population of Russia have not been identified among indigenous peoples, including the Buryats, Tuvinians and Altaians with hereditary breast cancer.

OBJECTIVE

This study was aimed to identify the mutations that are responsible for the occurrence of hereditary breast cancer in the indigenous population of the Republic of Buryatia.

METHODS

Mutations in the BRCA1 gene were identified in blood samples by Sanger-based sequencing.

RESULTS

We identified 11 polymorphisms (10 SNPs and 1 Indel) and 6 new unclassified sequence variants in the BRCA1 gene. In our study three new sequence variants (c.321T>A, c.366T>A, c.4357+2T>A) were found in position of previously described polymorphisms in dbSNPs: rs80357544 (c.321delT), rs190900046 (c.366T>G), and rs80358152 (c.4357+2T>C), respectively. Other three new sequence variants (c.3605A>G, c.1998A>C, and c.80+13A>C) have not been previously described in dbSNP, BIC and Human Gene Mutation Databases.

CONCLUSIONS

We described six new sequence variants that have never been published in the literature or databases. Further studies are required to confirm the impact of new sequence variants on the risk of breast cancer in the Buryat Mongol population.

Counsellee's experience of cancer genetic counselling with pedigrees that automatically incorporate genealogical and cancer database information

While pedigree drawing software is often utilised in genetic services, the use of genealogical databases in genetic counselling is unusual. This is mainly because of the unavailability of such databases in most countries. Electronically generated pedigrees used for cancer genetic counselling in Iceland create pedigrees that automatically incorporate information from a large, comprehensive genealogy database and nation-wide cancer registry. The aim of this descriptive qualitative study was to explore counsellees' experiences of genetic services, including family history taking, using these electronically generated pedigrees. Four online focus groups with 19 participants were formed, using an asynchronous posting method. Participants were encouraged to discuss their responses to questions posted on the website by the researcher. The main themes arising were motivation, information and trust, impact of testing and emotional responses. Most of the participants expressed trust in the method of using electronically generated pedigrees, although some voiced worries about information safety. Many experienced worry and anxiety while waiting for results of genetic testing, but limited survival guilt was noted. Family communication was either unchanged or improved following genetic counselling. The use of electronically generated pedigrees was well received by participants, and they trusted the information obtained via the databases. Age did not seem to influence responses. These results may be indicative of the particular culture in Iceland, where genealogical information is well known and freely shared. Further studies are needed to determine whether use of similar approaches to genealogical information gathering may be acceptable elsewhere.

Dose-response effects of aerobic exercise on estrogen among women at high risk for breast cancer: a randomized controlled trial

Medical and surgical interventions for elevated breast cancer risk (e.g., BRCA1/2 mutation, family history) focus on reducing estrogen exposure. Women at elevated risk may be interested in less aggressive approaches to risk reduction. For example, exercise might reduce estrogen, yet has fewer serious side effects and less negative impact than surgery or hormonal medications. Randomized controlled trial. Increased risk defined by risk prediction models or BRCA mutation status. Eligibility: Age 18-50, eumenorrheic, non-smokers, and body mass index (BMI) between 21 and 50 kg/m(2). 139 were randomized. Treadmill exercise: 150 or 300 min/week, five menstrual cycles. Control group maintained exercise <75 min/week.

PRIMARY OUTCOME

Area under curve (AUC) for urinary estrogen. Secondary measures: urinary progesterone, quantitative digitized breast dynamic contrast-enhanced magnetic resonance imaging background parenchymal enhancement. Mean age 34 years, mean BMI 26.8 kg/m(2). A linear dose-response relationship was observed such that every 100 min of exercise is associated with 3.6 % lower follicular phase estrogen AUC (linear trend test, p = 0.03). No changes in luteal phase estrogen or progesterone levels. There was also a dose-response effect noted: for every 100 min of exercise, there was a 9.7 % decrease in background parenchymal enhancement as measured by imaging (linear trend test, p = 0.009). Linear dose-response effect observed to reduce follicular phase estrogen exposure measured via urine and hormone sensitive breast tissue as measured by imaging. Future research should explore maintenance of effects and extent to which findings are repeatable in lower risk women. Given the high benefit to risk ratio, clinicians can inform young women at increased risk that exercise may blunt estrogen exposure while considering whether to try other preventive therapies.

Fluorescent reporters and methods to analyze fluorescent signals

The use of fluorescent reporters and the development of new imaging technologies have revolutionized studies in cell biology. During recent years the number of fluorescent proteins offering the ability to visualize the distribution of proteins, organelles, and cells has increased tremendously. In parallel, the imaging tools available were refined rapidly enabling now the use of a huge spectrum of specialized methods to explore the cellular and subcellular localization and dynamics of fluorescently tagged markers. This chapter presents an overview of fluorescent reporters and methods available, and describes a selection of those that are routinely applicable in imaging studies using Dictyostelium discoideum.

Exercise lowers estrogen and progesterone levels in premenopausal women at high risk of breast cancer

Experimental and clinical data support a role for estrogens in the development and growth of breast cancer, and lowered estrogen exposure reduces breast cancer recurrence and new diagnoses in high-risk women. There is varied evidence that increased physical activity is associated with breast cancer risk reduction in both pre- and postmenopausal women, perhaps via lowered estrogen levels. The purpose of this study was to assess whether exercise intervention in premenopausal women at increased breast cancer risk reduces estrogen or progesterone levels. Seven healthy premenopausal women at high risk for breast cancer completed a seven-menstrual-cycle study. The study began with two preintervention cycles of baseline measurement of hormone levels via daily first-morning urine collection, allowing calculation of average area under the curve (AUC) hormone exposure across the menstrual cycle. Participants then began five cycles of exercise training to a maintenance level of 300 min per week at 80-85% of maximal aerobic capacity. During the last two exercise cycles, urinary estradiol and progesterone levels were again measured daily. Total estrogen exposure declined by 18.9% and total progesterone exposure by 23.7%. The declines were mostly due to decreased luteal phase levels, although menstrual cycle and luteal phase lengths were unchanged. The study demonstrated the feasibility of daily urine samples and AUC measurement to assess hormone exposure in experimental studies of the impact of interventions on ovarian hormones. The results suggest value in exercise interventions to reduce hormone levels in high-risk women with few side effects and the potential for incremental benefits to surgical or pharmacologic interventions.

Population screening for hereditary and familial cancer syndromes in Valka district of Latvia

Background

The growing possibilities of cancer prevention and treatment as well as the increasing knowledge about hereditary cancers require proper identification of the persons at risk. The aim of this study was to test the outcome of population screening in the scientific and practical evaluation of hereditary cancer.

Methods

Population screening for hereditary cancer was carried out retrospectively in a geographic area of Latvia. Family cancer histories were collected from 18642 adults representing 76.6% of the population of this area. Hereditary cancer syndromes were diagnosed clinically. Molecular testing for BRCA1 founder mutations 300 T/G, 4153delA and 5382insC was conducted in 588 persons who reported at least one case of breast or ovary cancer among blood relatives.

Results

Clinically, 74 (0.40%; 95% confidence interval (CI): 0.32 - 0.50%) high-risk and 548 (2.94%, 95% CI: 2.71 - 3.19) moderate-risk hereditary cancer syndromes were detected covering wide cancer spectrum. All syndromes were characterised by high cancer frequency among blood relatives ranging 8.6 - 46.2% in contrast to spouse correlation of 2.5 - 3.6%. The mean age of cancer onset ranged 38.0 - 72.0 years in different syndromes. The BRCA1 gene mutations were identified in 10 (1.7%; 95% CI: 0.9 - 3.1%) probands. Families with established BRCA1 gene founder mutations were identified with the frequency 1:2663 clinically screened persons.

Conclusions

Population screening is a useful practical tool for the identification of persons belonging to families with high frequency of malignant tumours. The whole hereditary and familial cancer spectrum along with the age structure was identified adjusting follow-up guidelines. Another benefit of the population screening is the possibility to identify oncologically healthy persons belonging to hereditary and familial cancer families so that appropriate surveillance can be offered. Clinical diagnostics is appropriate for population screening purposes; molecular investigation provides additional information. In collaboration with family doctors, the screening is technically manageable as characterised by high compliance.

Hereditary ovarian cancer

At least 10% of ovarian tumors are hereditary and associated with highly penetrant, autosomal, dominant genetic predisposition. Three clinical manifestations of hereditary ovarian cancer have been identified: site-specific ovarian cancer, hereditary breast and/or ovarian cancer (HBOC) and hereditary non-polyposis colorectal cancer (HNPCC) syndromes. BRCA germline mutations account for more than 90% of all hereditary epithelial ovarian tumors whereas most of the remaining 10% are caused by MLH1 and MSH2 mutations, which are susceptibility genes of HNPCC. Genetic testing is available for each of the three hereditary syndromes above mentioned. The recommendations for OC surveillance in high-risk women having a strong family history or BRCA mutation carriers include transvaginal pelvic ultrasound with color Doppler and serum CA125 every 6 months. Bilateral salpingo-oophorectomy appears to be effective to reduce the risk of ovarian cancer in BRCA mutation carriers. Hysterosalpingo-oophorectomy should be considered in HNPCC women who undergo surgery for colorectal carcinoma.

Is HRT justified for symptom management in women at higher risk of developing breast cancer?

Hormone replacement therapy (HRT) is the most efficacious intervention for the treatment of estrogen-deficiency symptoms. Prescriptions for HRT have fallen over the last 3 years due to anxiety provoked about breast cancer risk and recurrence that has been generated by recent clinical trials. In women at population risk of breast cancer, these trials have not shown risks greater than estimates from clinical trial evidence that predated them. For women at increased breast cancer risk due to a family history or high-risk benign breast conditions, clinical trial data are limited but suggest a lack of an additive effect of HRT on risk. In symptomatic breast cancer survivors, observational data suggest no increase in recurrence but these data are open to bias. Interim analyses of large, randomized trials have shown contradictory outcomes and, as a result, three large HRT randomized trials have now been closed. The randomized LIBERATE trial evaluating tibolone in breast cancer survivors is fully recruited and continuing. The current clinical climate is 'HRT adverse' but, due to a lack of effective alternatives for symptom relief, women at higher breast cancer risk and breast cancer survivors are still requesting information about HRT. In this situation, discussion of the current clinical uncertainty surrounding the use of HRT must be undertaken to ensure that women are adequately informed.

Cancer Genetics

OBJECTIVES

To provide a basic overview of genetics, focusing on breast and ovarian cancer susceptibility mutations on BRCA1 and BRCA2.

DATA SOURCES

Research and review articles and government internet sites.

CONCLUSION

The advances in molecular biology has enabled health care providers to be proactive rather than reactive in predicting some cancers and offering prevention strategies to greatly reduce the risk of developing cancer. Our expanding knowledge base of genetics may one day provide tailored treatment, and predict recurrence rates for all cancers.

IMPLICATIONS FOR NURSING PRACTICE

The science of genetics will impact every aspect of health care, from primary care to specialized care. Nurses are on the front line and will be expected to recognize patterns of disease that may indicate a possible genetic link, educate the family about the implications of a potential genetic susceptibility and refer the family for counseling. To accomplish this, each nurse should have a minimum basic knowledge of genetics, and formal education for those who educate and counsel.

Family history of breast cancer as a risk factor for ovarian cancer in a prospective study

BACKGROUND

A family history of breast cancer has been associated with increased ovarian cancer risk. However, few studies have assessed risk according to characteristics that suggest an inherited cancer susceptibility disorder, such as earlier-than-usual age at cancer diagnosis, family members with double primary cancers of different types, multiple relatives with cancer, and cancer in both members of paired organs.

METHODS

Ovarian cancer risk was assessed according to a detailed breast cancer family history among 49,975 participants in the Breast Cancer Detection Demonstration Project Breast Cancer Defection Demenstration Project (BCDDP) Follow-up Study (1979-1998). In all, 362 incident ovarian cancers were identified during follow-up and rate ratios (RRs) were calculated by Poisson regression. RESULTS.: Breast cancer in a first- or second-degree relative was associated with increased risk of ovarian cancer (RR = 1.4; 95% confidence interval [CI] = 1.1-1.7). Having 2 or more affected first-degree relatives was associated with increased risk (RR = 1.8; 95% CI = 1.1-2.8), especially for women diagnosed with ovarian cancer before age 60 (RR = 4.2; 95% CI = 1.9-9.2) or with a personal history of breast cancer (RR = 3.7; 95% CI 1.8-7.7). Risk was also particularly high for women with 2 or more first-degree relatives with breast cancer and at least 1 affected relative diagnosed before age 50 (RR = 2.6; 95% CI = 1.4-4.8) or with bilateral breast cancer (RR = 4.2; 95% CI = 1.7-10).

CONCLUSIONS

A detailed breast cancer family history as well as an individual's age and personal history of breast cancer are useful for identifying women at elevated genetic risk of ovarian cancer.

Genetic epidemiology and public health: hope, hype, and future prospects

Genetic epidemiology is a rapidly expanding research field, but the implications of findings from such studies for individual or population health are unclear. The use of molecular genetic screening currently has some legitimacy in certain monogenic conditions, but no established value with respect to common complex diseases. Personalised medical care based on molecular genetic testing is also as yet undeveloped for common diseases. Genetic epidemiology can contribute to establishing the causal nature of environmentally modifiable risk factors, through the application of mendelian randomisation approaches and thus contribute to appropriate preventive strategies. Technological and other advances will allow the potential of genetic epidemiology to be revealed over the next few years, and the establishment of large population-based resources for such studies (biobanks) should contribute to this endeavour.