Genetic predisposition to breast cancer

RAD51D has been reported as a breast cancer (BC) and ovarian cancer (OC) predisposition gene, particularly among Caucasian populations. We studied the prevalence of RAD51D variants in Pakistani BC/OC patients. In total, 371 young or familial BC/OC patients were thoroughly analyzed for RAD51D sequence variants using denaturing high-performance liquid chromatography pursued by DNA sequencing of differentially eluted amplicons. We also assessed the pathogenic effects of novel variants using in-silico algorithms. All detected RAD51D variants were investigated in 400 unaffected controls. No pathogenic RAD51D variant was detected. However, we identified nine unique heterozygous variants. Of these, two missense variants (p.Pro10Leu and p.Ile311Asn) and one intronic variant (c.481-26_23delGTTC) were classified as in silico-predicted variants of uncertain significance, with a frequency of 0.8% (3/371). The p.Pro10Leu variant was detected in a 28-year-old female BC patient of Punjabi ethnic background, whose mother and maternal cousin had BCs at ages 53 and 40, respectively. This variant was also detected in 1/400 (0.25%) healthy controls, where the control subject's daughter had acute lymphoblastic leukemia. The p.Ile311Asn variant was identified in a female BC patient at age 29 of Punjabi ethnicity and in 1/400 (0.25%) healthy controls, where the control subject's daughter had Hodgkin's disease at age 14. A novel intronic variant, c.481-26_-23delGTTC, was found in a 30-year-old Punjabi female BC patient but not in 400 healthy controls. No pathogenic RAD51D variant was identified in the current study. Our study data suggested a negligible association of RAD51D variants with BC/OC risk in Pakistani women.

Breast cancer is the most common type of cancer, and has a strong heritable component, with approximately 15 percent of new cases having family history of breast cancer. Genetic panel testing for patients with a family history of breast cancer has become a popular clinical resource. However, the risk of breast cancer associated with inactivating mutations in the predisposition genes is largely undefined, creating critical limitations in the interpretations of the results from panel testing and subsequent medical management. The Cancer Risk Estimates Related to Susceptibility Genes (CARRIERS) consortium was established to determine the risk of cancers associated with truncating mutations in the known predisposition genes and to extend these studies to the clinical classification of variants of uncertain significance (VUS) in the relevant genes. CARRIERS involves screening of approximately 30,000 population-based breast cancer cases and 30,000 study matched controls for mutations in 28 established or proposed breast cancer predisposition genes. Population-based risks for breast cancer associated with mutations in each gene will be estimated. In parallel, 10,000 breast cancer cases from moderate and high-risk breast cancer families will be similarly screened for mutations and the penetrance of the mutations in high-risk families will be estimated. Furthermore, VUS identified by mutation screening will be characterized by functional and family-based studies and models for classification of the clinical relevance of VUS in each gene will be developed. These data are expected to lead to improvements in cancer risk assessment and improved management of patients found to carry mutations or VUS in breast cancer predisposition. Citation Format: Jenna Lilyquist, Peter Kraft, Steven N. Hart, Emily J. Hallberg, Chunling Hu, Raymond Moore, Rohan Gnanaolivu, Susan M. Domchek, Jeffrey N. Weitzel, Katherine L. Nathanson, David E. Goldgar, Fergus J. Couch. The CARRIERS consortium: Establishing refined breast cancer risk estimates in known predisposition genes. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 810.

An estimated 5%–10% of cancer results from an underlying genetic predisposition. For the majority of familial cases, the genes in question remain unknown, suggesting a critical need to identify new cancer predisposition genes. Members of the protein phosphatase 2A (PP2A) family exist as trimeric holoenzymes and are vital negative regulators of multiple oncogenic pathways. PP2A inhibition by somatic mutation, loss of expression, and upregulation of its exogenous inhibitors in tumors has been well described. However, it remains unknown whether germline loss of any PP2A subunits results in a predisposition to cancer in humans. In this study, we identified 9 cancer patients with germline loss-of-function (LOF) variants in PPP2R1B (Aβ), the β isoform of the PP2A scaffold subunit. All 4 patients for whom documentation was available also had a family history of cancer, including multiple indicators of hereditary cancer. Overexpression of these mutant forms of Aβ resulted in truncated proteins that were rapidly turned over. Characterization of an additional missense germline Aβ variant, R233C, which is also recurrently mutated at the somatic level, showed disruption of PP2A catalytic subunit binding, resulting in loss of phosphatase activity. An analysis of Aβ expression among multiple breast cancer cohorts (the most highly represented cancer among the Aβ germline patients) revealed that somatic, heterozygous loss of Aβ was a frequent event in this disease, and decreased Aβ expression correlated with shorter disease-free and overall survival. Furthermore, Aβ levels were significantly lower in multiple histological subtypes of both in situ and malignant breast cancer compared with adjacent normal breast tissue, suggesting that Aβ loss is an early event in breast cancer development. Together, these results highlight a role for Aβ as a predisposition gene in breast cancer and potentially additional cancers.

Objective To investigate the methylation of HOXA4 in breast cancer patients and its correlation with clinicopathological characteristics. Methods NEBNext® Ultra™ RNA Library Prep Kit for Illumina® was used for gene expression microarray and the screening of abnormally expressed genes in breast cancer tissues and adjacent breast tissues from 9 breast cancer patients (enrolled by a random number table)in Bao’an Maternal and Child Health Hospital in 2014. Illumina Infinium HD Methylation450K Assay was used for DNA methylation microarray and detection of differentially methylated genes in breast cancer. Then the differentially expressed genes and methylated genes in breast cancer were further explored based on The Cancer Genome Atlas (TCGA). The genes with significant hypermethylation and low expression were selected. Combined with bioinformatics, HOXA4 was identified as a candidate gene, with the potential for the detection of early breast cancer. The methylation and mRNA expression of HOXA4 gene in breast cancer tissues and adjacent breast tissues from 86 breast cancer patients (enrolled by a random number table)in Bao’an Maternal and Child Health Hospital from 2014 to 2017 were detected by pyrophosphoric acid sequencing and RT-PCR. And the correlation between HOXA4 mehtylation and the clinicopathological characteristics was also analyzed by the Fisher exact test. Cox proportional hazards model was used for univariate and multivariate analysis of risk factors. The breast cancer MCF-7 cells were treated with 0, 0.5, 1, 5, 10, 20 μmol/L methylation inhibitor RG108 for 5 days, then HOXA4 mRNA expression was detected. Results The gene expression microarray showed that 1 680 upregulated genes and 1 249 downregulated genes were determined in breast cancer tissue. The overall methylation levels in different regions of breast cancer tissues were significantly higher than those in adjacent tissues (All P<0.001). In 86 breast cancer patients, the methylation rate of HOXA4 gene was 95% (82/86) in breast cancer tissue(52 samples with low methylation and 30 with hypermethylation), 57% (49/86) in the corresponding adjacent tissues (49 samples with low methylation and none with hypermethylation) (χ2=4.779, P=0.029). The expression of HOXA4 mRNA in HOXA4 methylation group was significantly lower than that in non-methylation group (P=0.031). HOXA4 methylation was correlated with lymph node metastasis(P=0.039) and ER negative (P=0.017). Univariate analysis showed that TNM stage, histological grade, lymph node metastasis and HOXA4 methylation were risk factors for DFS (RR=4.008, 95%CI=1.296-12.393, P=0.016; RR=10.111, 95%CI=2.607-39.217, P=0.001; RR=4.588, 95%CI=1.201-17.523, P=0.026; RR=1.051, 95%CI=1.007-1.098, P=0.024). Multivariate analysis showed that histological grade was an independent prognostic factor for DFS in breast cancer patients (RR=14.461, 95%CI=2.429-86.100, P=0.003). After treatment with different concentrations of RG108, the expression of HOXA4 mRNA in MCF-7 cells was significantly different among six groups (χ2=4.472, P=0.029). Conclusion The methylation of HOXA4 plays an important role in the occurrence and development of breast cancer, which may serve as a novel molecular biological marker for clinical diagnosis of breast cancer. Key words: Breast neoplasms; Gene, HOXA4; Methylation

In the past few decades, the diagnosis, prevention, and treatment of BRCA1/2-related cancer, especially breast cancer and ovarian cancer, have been a topic of great concern to scientists and the public. People with mutated BRCA genes are more likely to develop breast and ovarian cancer, and such causes of these types of cancer are inherited. Till now, there is no perfect solution for this gene defect. microRNAs (miRNAs), as important gene expression regulation molecules in humans, are considered to have the potential to be a tool for early diagnosis of such gene defects. In this review, the literature on miRNA closely related to BRCA gene regulation is reviewed, and the mechanism of miRNA causing BRCA gene variation is discussed. The online databases used in this research are PubMed, Nature Journals, ScienceDirect, The European Bioinformatics Institute (EBI), and Google Scholar. The search terms are “BRCA gene mutation”, “BRCA gene function”, “PARP inhibitor”, “miRNA for BRCA regulation”, “Target therapy for BRCA gene mutation”, “Drug resistance”, and “Target specificity”. This paper aims to discuss the possibility of reducing the incidence of BRCA gene mutation by controlling the content of relative miRNAs – reducing miRNAs that inhibit BRCA gene expression and increasing miRNAs that promote BRCA gene expression– and how to restore the function of the mutated BRCA gene by this means. The population that develops breast and ovarian cancer has been on the rise for decades, and the age of patients is getting younger. If miRNA can be developed as an early diagnostic tool, it will enhance the power of current cancer screening techniques and provide a more stable basis for early prevention and subsequent treatment.

270P - Evaluation of germ line mutational status among women with triple-negative breast cancer in Russia

10554 Background: Uptake of chemoprevention and prophylactic surgery among women at high risk for breast cancer is low, despite proven efficacy. We evaluated breast cancer risk factors as predictors of uptake of prevention treatment (PT) to better understand potential associations with these decisions. Methods: An IRB approved registry established in 2003 at the University of Vermont of high-risk women was used to evaluate the association between both modifiable (obesity, sedentary lifestyle and alcohol use) and non-modifiable (age, history of benign breast disease [BDD], genetic predisposition) risk factors and uptake of PT. Women were eligible for inclusion in this analysis if they had one of the following risk factors (BDD, strong family history, &gt; 20% lifetime modeled risk or genetic predisposition) and completed questionnaires regarding diet and physical activity. Alcohol use was assessed using a health questionnaire and physical activity was assessed using a 7-Day Physical Activity Recall questionnaire. We used logistic regression to estimate odds ratios (OR). Results: 504 women were included and had been followed for median of 13 years. Mean age was 44.5 years (range 19 – 75), 98% were Caucasian, and mean BMI was 26.9 (range 17-57). 78% had a family history of breast cancer, 60% had &gt;20% lifetime modeled risk, 14% had a history of benign breast disease (BBD), and 9% of women had confirmed genetic risk in high or moderate risk genes. Women may have had more than one risk factor. 55% were physically active and 55%. 4.2% were sedentary and 12.3% consumed &gt; 1 alcoholic beverage daily. 20.8% of the cohort participated in PT (8.1% took chemoprevention, 2.0% underwent prophylactic bilateral total mastectomy and 10.7% underwent risk reducing salpingo-oophorectomy). Among non-modifiable risk factors, age, genetic predisposition (ORadj 8.66, 95% CI 2.30–32.33, p &lt; 0.0001), and history of benign breast disease (ORadj 4.09, 95% CI 1.89–8.86, p &lt; 0.001) were associated with uptake of PT. Increasing age was associated with increasing uptake (ptrend was &gt; 0.0001) and highest among women aged 60-69 years (ORadj8.19, 95% CI 2.87-23.37 relative to women aged &lt; 40). Women with a strong family history were significantly less likely to take up PT (p = 0.04). BMI, physical activity status and alcohol use were not associated with uptake of PT. Conclusions: Like other studies, we found a low uptake of PT among women at high risk for developing breast cancer. We found that modifiable risk factors were not associated with uptake of PT, which might suggest that high-risk women with modifiable risk factors could be targeted for interventions designed to modify risk (i.e. chemoprevention, weight reduction, etc). Interestingly, women with a strong family history may be less likely to take up PT, and studies to further examine this relationship may identify opportunities for interventions to improve uptake.

Understanding, and Reversing, Metabolic Memory Is Within Reach

Family history has long been recognized to be a potent risk factor for breast cancer [1]. Family histories often comprise only one or two affected relatives, who frequently were not particularly young at onset. Occasionally, a family contains a striking constellation of young-onset breast (and often other) cancers apparently transmitted as a dominant genetic trait. Over a century ago, the much referenced French neurologist Paul Broca wrote about the family of his wife, in which the occurrence of many cancers, particularly of the breast, strongly suggested the presence of a genetic predisposition [1]. It was to be more than a hundred years before the discovery of the structure of DNA and rapid advances in molecular technology would allow the first major breast cancer susceptibility gene, BRCA1, to be mapped to chromosome 17q [2]. In families linked to the BRCA1 locus, a much younger age at onset than average and the frequent occurrence of ovarian cancers were noted to be typical. At about the same time, the cause of a rare but devastating familial cancer syndrome was identified; mutations in the TP53 gene had also been found to account for the very rare Li Fraumeni syndrome associated with very young onset breast cancers and childhood malignancy, particularly soft tissue sarcomas [3,4]. A second major breast cancer susceptibility gene, BRCA2, was mapped to chromosome 13q in 1994 shortly before the sequence of the BRCA1 gene was clarified and family-specific disease-causing mutations started to be reported [5,6]. The full BRCA2 gene sequence was reported in 1995 [7]. Families with mutations in the BRCA2 gene were noted to be more likely to contain a male breast cancer case than might be expected by chance (and more than had been seen in families due to BRCA1 mutations); ovarian and fallopian tube cancers still occurred with increased frequency but overall not as frequently as in BRCA1-associated families. With the discovery of the correct gene sequences for BRCA1 and BRCA2 it became possible to offer predictive genetic testing to members of families in which the causative gene mutation had been identified. Predictive testing for breast cancer susceptibility was introduced as a clinical service from the mid-1990s in some centres in the UK [8]. Families in which mutations were identified through research studies were the first to be informed [9]. Many of these families had been identified because of their high incidence of cancer, and so inevitably the estimated lifetime chance that a carrier of one of these genes would develop cancer was high [10,11]. The BRCA1 and BRCA2 genes are very large, and mutation testing was either very expensive (in the USA) or very slow (in European countries) when it first became available. It soon became clear that mutations in these genes accounted for a relatively small proportion of all families with breast cancer clusters. Families with four or more cancer cases developing at young age, particularly those families in which ovarian cancers occurred, were more likely to yield pathogenic mutations when DNA from a cancer-affected family member was screened for mutations. Smaller clusters of later onset cancers, although clearly familial, were noted to have a much lower probability of harbouring a BRCA1 or BRCA2 mutation [12]. In the presence of a BRCA1 or BRCA2 mutation, the lifetime risk for developing breast cancer may be as high as 80% to 90%, although other genes and lifestyle factors may reduce the lifetime risk to levels as low as 26%. Ovarian cancer risk in BRCA1 gene carriers is estimated at about 50%, but again this risk is likely to be modified by both genetic and other risk factors. For BRCA2, ovarian cancer risk is about 15%, but all these average risks are likely to be modified by context [13].

Metaplastic breast cancer (MpBC) is a rare, aggressive breast cancer (BC) histotype. Scarce information is available about MpBC genetic predisposition. Previous studies, mainly consisting of case reports, retrospective reviews and others on target therapies, pointed to a possible involvement of the BRCA1 gene in increasing MpBC risk, without ever confirming it. In this study, we retrospectively reviewed all BC patients counseled at our Institute for genetic testing of at least BRCA1 or BRCA2 (BRCA) genes and we found that 23 (23/5226 = 0.4%) were affected by MpBC. About 65% (15/23) of MpBC patients harbored a germline pathogenic variant (PV): 13 in BRCA1 (86.7%), including two patients who received genetic testing for known familial PV, one in TP53 (6.7%), and one in MLH1 (6.7%). We observed a statistically different frequency of MpBC in patients who carried a PV in the BRCA genes (13/1114 = 1.2%) vs. all other BC patients (10/4112 = 0.2%) (p = 0.0002). BRCA carriers proved to have an increased risk of developing MpBC compared to all other BC patients who were tested for BRCA genes (OR = 4.47; 95% CI: 1.95-10.23). Notably, MpBCs were diagnosed in 2.1% (13/610) of BRCA1 carriers. No MpBCs were observed in BRCA2 carriers (0/498 = 0%), revealing a statistically significant difference between the prevalence of MpBCs in BRCA1 and BRCA2 carriers (p = 0.0015). Our results confirmed that BRCA1 is involved in MpBC predisposition. Further studies on unselected patients are needed to elucidate the authentic role of BRCA1 and to explore the possible implication of other genes in MpBC predisposition.

BackgroundGerm-line mutations in the BRCA1 and BRCA2 genes are major contributors to hereditary breast/ovarian cancer. Large rearrangements are less frequent in the BRCA2 gene than in BRCA1. We report, here, the first total deletion of exon 3 in the BRCA2 gene that was detected during screening of 2058 index cases from breast/ovarian cancer families for BRCA2 large rearrangements. Deletion of exon 3, which is in phase, does not alter the reading frame. Low levels of alternative transcripts lacking exon 3 (Δ3 delta3 transcript) have been reported in normal tissues, which raises the question whether deletion of exon 3 is pathogenic.MethodsLarge BRCA2 rearrangements were analysed by QMPSF (Quantitative Multiplex PCR of Short Fluorescent Fragments) or MLPA (Multiplex Ligation-Dependent Probe Amplification). The exon 3 deletion was characterized with a "zoom-in" dedicated CGH array to the BRCA2 gene and sequencing. To determine the effect of exon 3 deletion and assess its pathogenic effect, three methods of transcript quantification were used: fragment analysis of FAM-labelled PCR products, specific allelic expression using an intron 2 polymorphism and competitive quantitative RT-PCR.ResultsLarge rearrangements of BRCA2 were detected in six index cases out of 2058 tested (3% of all deleterious BRCA2 mutations). This study reports the first large rearrangement of the BRCA2 gene that includes all of exon 3 and leads to an in frame deletion of exon 3 at the transcriptional level. Thirty five variants in exon 3 and junction regions of BRCA2 are also reported, that contribute to the interpretation of the pathogenicity of the deletion. The quantitative approaches showed that there are three classes of delta3 BRCA2 transcripts (low, moderate and exclusive). Exclusive expression of the delta3 transcript by the mutant allele and segregation data provide evidence for a causal effect of the exon 3 deletion.ConclusionThis paper highlights that large rearrangements and total deletion of exon 3 in the BRCA2 gene could contribute to hereditary breast and/or ovarian cancer. In addition, our findings suggest that, to interpret the pathogenic effect of any variants of exon 3, both accurate transcript quantification and co-segregation analysis are required.

Context About 5-10% of adrenocortical cancer (ACC) arise in patients with genetic predisposition syndromes, including Li-Fraumeni, Lynch, MEN1, or Familial Adenomatous Polyposis (APC). Recent European (2018) and American guidelines (2020) recommend that all adults with ACC should be offered clinical genetic counseling. There is a paucity of data regarding systematic germline testing in adults with ACC and the extent of the genetic evaluation is unclear. Objective To describe the germline genetic characteristics in a cohort of adult patients with ACC evaluated in a tertiary clinical care center. Methods Data including demographics, personal and family history of neoplasia, pathology reports, clinical features and genetic testing were retrospectively collected from charts of patients treated at Centre hospitalier de l'Université de Montréal (CHUM). After genetic counseling, genetic testing was proposed to patients with a pathologic diagnosis of ACC. From 2005 to 2015, TP53 gene analysis was performed using direct sequencing and MLPA. Since 2016, multigene testing was performed for a progressively increasing number of oncogenic genes using a custom next-generation panel for germline leucocyte DNA including at least the TP53, MSH2, MSH6, MLH1,PMS2, EPCAM, MEN1, BRCA1 and BRCA2 genes (Invitae, CA). An extended panel, based on past medical and familial history, was performed at the discretion of the geneticist. Patient data was retrospectively investigated. Results We analyzed data from 44 patients with available germline genetic results. Median age of the patients was 46 years (ranging from 22 to 79 years), including 11 males (25.0%) and 33 females (75.0%). Ten patients (22.7%) underwent only TP53 gene analysis and 32 patients (72.7%) were studied using the larger oncogenic genetic panel. Germline pathogenic or likely pathogenic variants were identified in 5 of the 44 patients (11.4%) while genetic variants of unknown significance (VUS) were found in 7 of the 44 patients (15.9%). Among patients with pathogenic variants, one had a family history and known germline mutation in the BRCA2 gene (8765delAG, p.Glu2846GlyfsX23). One patient had a personal and familial medical history suggesting a MEN1 syndrome that was confirmed with the finding of a germline MEN1 mutation (c.1556delC, p.Pro519Leu fs40). Unsuspected germline pathogenic variants were found in three patients: 1) TP53 (c.425delC, p.Pro142fs), 2) MUTYH (c.536A&amp;gt;G, p.Tyr179Cys) and 3) MSH6 (c.3649-3655, p.Arg1217Leu fs9) genes. Variants of unknown significance (VUS) were found in the following genes: POT1, MSH3, PALB2, RAD51d, APC, ATM and BRCA2. Conclusions Germline pathogenic variants were found in 11.4% of our cohort of patients with ACC. VUS were found in 15.9% of patients but their significance remains to be determined. Genetic counseling and germline genetic testing should be offered to all patients with ACC; however the optimal use and extent of oncogenic gene panels need to be better defined. Presentation: Sunday, June 12, 2022 12:30 p.m. - 2:30 p.m., Sunday, June 12, 2022 12:48 p.m. - 12:53 p.m.

To the Editor, Breast-Cancer Risk in Families with Mutations in PALB2: A.C. Antoniou, S. Casadei, T. Heikkinen, et al. N Engl J Med. 2014;371:497-506. In a study published in N Engl J Med. August 2014, researchers from 14 centers in eight countries investigated information from 362 family members from 154 families who had an abnormal partner and localizer of BRCA2 (PALB2) gene, but did not have an abnormal BRCA1 or BRCA2 gene. Their aim was to demonstrate the importance of loss-of-function mutations in PALB2 as a cause of hereditary breast cancer. The study included 311 women with an abnormal PALB2 gene; 229 of these women had been diagnosed with breast cancer and 51 men with an abnormal PALB2 gene; seven of whom had been diagnosed with breast cancer. The researchers compared the breast cancer risk of the study population to the general population. They found out that overall, women with an abnormal PALB2 gene had a risk of breast cancer that was 9.47 times higher than average. Women with an abnormal PALB2 gene had a 14% risk of developing breast cancer by age 50 and a 35% risk of developing breast cancer by age 70. The average lifetime risk of breast cancer is about 12%. This increase in risk linked to an abnormal PALB2 gene was dependent on the women’s age and family history. They have demonstrated that the relative risk of breast cancer among PALB2 mutation carriers increased significantly as birth cohort became more recent (P<0.001). In women with an abnormal PALB2 gene, breast cancer risk was eight to nine times higher than average in women aged 20 to 39, six to eight times higher than average in women aged 40 to 60, and five times higher than average in women older than 60 years of age. By the age of 70, women with an abnormal PALB2 gene with no family history of breast cancer had a 33% risk of developing breast cancer whereas women with two or more first-degree relatives with breast cancer at 50 years of age had a 58% risk of developing the disease. The authors concluded that based on their estimates, breast cancer risk for a PALB2 mutation carrier, even in the absence of a family history of breast cancer, would be classified as high according to various guidelines. The researchers also reported that this level of risk may justify adding PALB2 to genetic testing for BRCA1 and BRCA2. A Genetic counselor’s perspective Partner and localizer of BRCA2 (PALB) is a gene whose protein facilitates the function of BRCA2 and interacts with BRCA1 to aid in repairing double strand and interstrand cross-link DNA damage. Biallelic PALB2 mutations cause Fanconi Anemia complement group N (FANCN) and monoallellic mutations in the PALB2 gene are associated with increased breast and pancreas cancer risks (1). PALB2 mutations may account for as much as 3% of familial breast cancer risk (2). A recent study of 362 members from PALB2 mutation positive families found that the risk for breast cancer in female mutation carriers ranged between 33% to 58% by age 70, with the higher risks relating to those women with a family history of early onset (<50) breast cancer in 2 first degree family members (3). The study also identified an 8 fold increase in male breast cancer risk and a 2 fold increase in ovarian cancer risk, both of which need to be confirmed in additional studies due a lack of statistical significance. These data suggest that female PALB2 mutation carriers may have breast cancer risks that are similar to those conferred by mutations in the BRCA2 gene. These findings suggest that women who carry PALB2 gene mutations may warrant similar breast cancer screening and prevention strategies as those offered to BRCA2 mutation carriers. PALB2 mutation analysis is available and is rapidly being adopted into clinical practice. As the data continues to accumulate it is likely that PALB2 mutation analysis will become a standard part of genetic testing in the realm of hereditary breast cancer predisposition. Whether testing will be done in addition to BRCA1/2 or as part of a larger breast cancer gene panel remains to be determined. In addition, more data will provide evidence to support the development of specific management guidelines to aid in the care of these at risk patients.

The evolving field of personalised medicine is playing an increasingly important role in cancer prevention, diagnosis, prognosis and therapeutics. Its importance in clinical management is demonstrated by the recent introduction into routine clinical practice of various individualised, molecularly targeted therapies with increased efficacy and/or reduced toxicity. The identification of cancer predisposition genes, such as the BRCA genes in breast cancer, permits screening programmes to identify patients "at-risk" of developing cancer and helps them make decisions on individual risk-modification behaviours. Personalised medicine also plays an increasingly important role in cancer treatment. It is increasingly clear that there are molecularly distinct subtypes of various common cancers, with different therapeutic approaches required for each subtype, for example, the use of the monoclonal antibodies (trastuzumab and cetuximab) in HER2-positive breast cancer and wild-type KRAS colorectal cancer; tyrosine kinase inhibitors (imatinib, gefitinib, erlotinib and crizotinib) in chronic myeloid leukaemia, gastrointestinal stromal tumours and non-small-cell lung cancer and intracellular agents (vemurafenib and olaparib) in metastatic malignant melanoma and ovarian, breast and prostate cancer. The efficacy of various targeted therapies in such disparate tumours suggests that we are entering an era in which treatment decisions will be based on tumour molecular abnormality profile or "signature," rather than tumour tissue type or anatomical site of origin, improving patient prognosis and quality of life. This mini review focuses on the role of personalised medicine in cancer prevention and treatment as well as its future direction in oncology.

After two decades of genetic testing and research, the BRCA1 and BRCA2 genes are two of the most well-characterized genes in the human genome. As a result, variants of uncertain significance (VUS; also called variants of unknown significance) are reported less frequently than for genes that have been less thoroughly studied. However, VUS continue to be uncovered, even for BRCA1/2. The increasing use of multi-gene panels and whole-genome and whole-exome sequencing will lead to higher rates of VUS detection because more genes are being tested, and most genomic loci have been far less intensively characterized than BRCA1/2. In this article, we draw attention to ethical and policy-related issues that will emerge. Experience garnered from BRCA1/2 testing is a useful introduction to the challenges of detecting VUS in other genetic testing contexts, while features unique to BRCA1/2 suggest key differences between the BRCA experience and the current challenges of multi-gene panels in clinical care. We propose lines of research and policy development, emphasizing the importance of pooling data into a centralized open-access database for the storage of gene variants to improve VUS interpretation. In addition, establishing ethical norms and regulated practices for sharing and curating data, analytical algorithms, interpretive frameworks and patient re-contact are important policy areas.Electronic supplementary materialThe online version of this article (doi:10.1186/s13073-014-0121-3) contains supplementary material, which is available to authorized users.