Homologous recombination DNA repair defects in PALB2- associated breast cancers

Abstract: Mono-allelic germline pathogenic variants in the Partner And Localizer of BRCA2 (PALB2) gene predispose to a high-risk of breast cancer development, consistent with the role of PALB2 in homologous recombination (HR) DNA repair. Here, we sought to define the repertoire of somatic genetic alterations in PALB2-associated breast cancers (BCs), and whether PALB2-associated BCs display bi-allelic inactivation of PALB2 and/or genomic features of HR-deficiency (HRD). Twenty-four breast cancer patients with pathogenic PALB2 germline mutations were analyzed by whole-exome sequencing (WES, n = 16) or targeted capture massively parallel sequencing (410 cancer genes, n = 8). Somatic genetic alterations, loss of heterozygosity (LOH) of the PALB2 wild-type allele, large-scale state transitions (LSTs) and mutational signatures were defined. PALB2-associated BCs were found to be heterogeneous at the genetic level, with PIK3CA (29%), PALB2 (21%), TP53 (21%), and NOTCH3 (17%) being the genes most frequently affected by somatic mutations. Bi-allelic PALB2 inactivation was found in 16 of the 24 cases (67%), either through LOH (n = 11) or second somatic mutations (n = 5) of the wild-type allele. High LST scores were found in all 12 PALB2-associated BCs with bi-allelic PALB2 inactivation sequenced by WES, of which eight displayed the HRD-related mutational signature 3. In addition, bi-allelic inactivation of PALB2 was significantly associated with high LST scores. Our findings suggest that the identification of bi-allelic PALB2 inactivation in PALB2-associated BCs is required for the personalization of HR-directed therapies, such as platinum salts and/or PARP inhibitors, as the vast majority of PALB2-associated BCs without PALB2 bi-allelic inactivation lack genomic features of HRD

Experiences and interpretations of BRCA1/2 testing among women affected by breast or ovarian cancer who received a negative result

The aim of this study was to retrospectively describe the genetic testing motives and experiences of women with a previous breast and/or ovarian cancer diagnosis, who received negative BRCA1/2 results including variants of unknown significance and no pathogenic variant detected. One hundred and thirteen women (mean age 56.17 years) were recruited from a familial cancer centre in metropolitan Australia, an average 3.4 years after undergoing testing. Participants completed a self-report questionnaire focusing on the retrospective experience of and motives for undergoing BRCA1/2 testing. The study found that the primary motives for undergoing BRCA1/2 testing were (a) to know more about whether their cancer was hereditary, and (b) to have more certainty about the risk of their children developing cancer. In terms of perceptions of personal risk, 35% of women perceived that their risk of breast cancer to be the same or lower than the general population and 80% believed the negative test result to mean that a risk-conferring gene had not been detected. Yet, the average estimate of the likelihood that their cancer was hereditary was 48 out of a possible 100. Psychologically, women did not interpret the negative BRCA1/2 result as a positive outcome. Half were not relieved by the result and were as or more worried than before. Psychological morbidity was high with 17%, 100%, and 36% experiencing clinically significant depression, anxiety, and cancer-specific distress, respectively. Self-ratings of the likelihood that their cancer was hereditary were more closely associated with their personal family cancer histories than with measures of psychological distress. These results have implications for adherence to risk-reducing behaviours and quality of life. Given that these women are not routinely followed up in clinical practice, these findings highlight the importance of post-test genetic counselling and longer-term follow-up for women with negative BRCA1/2 results. Additional time and emotional support from genetic counsellors may help this group of women make sense of the meaning of their test result and adjust psychologically, particularly to uncertainty around the cause of their family history

Pilot study of an online training program to increase genetic literacy and communication skills in oncology healthcare professionals discussing BRCA1/2 genetic testing with breast and ovarian cancer patients

The increasing use of genetic testing for BRCA1/2 and other pathogenic variants in the management of women with breast and ovarian cancer necessitates increased genetic literacy in oncology healthcare professionals. This pilot study aimed to evaluate an online training program to increase genetic literacy and communication skills in Australian oncology healthcare professionals tasked with discussing and coordinating mainstream genetic testing with breast and ovarian cancer patients. A training website with embedded videos was developed. This study assesses the website’s acceptability and user-friendliness; suggestions for improvement were also elicited. Oncology healthcare professionals were recruited through relevant professional organisations, invited to the study by email, asked to work through the website and then complete an online questionnaire. Thirty-two oncology healthcare professionals completed the questionnaire after viewing the website. Nearly all participants were satisfied with the information contained in the program (very satisfied: n=14/32, 44%, satisfied: n=17/32, 53%, neither satisfied nor dissatisfied: n=1/32, 3%) and reported that they had gained new skills (n=29/32, 91%) and had increased confidence (n=29/31, 94%) in communicating with breast and ovarian cancer patients about genetic testing. More than 93% (28/30) of participants endorsed the online program as clearly presented, informative, relevant and useful. This pilot study demonstrated high feasibility and acceptability of the training program to increase genetic literacy and communication skills in oncology healthcare professionals discussing genetic testing with breast and ovarian cancer patients. Further evidence from a randomised trial is needed to evaluate effects on changing clinical practice, improving patient outcomes, and cost-effectiveness

Publisher correction: Homologous recombination DNA repair defects in PALB2-associated breast cancers

Original article published in "npj Breast Cancer, (2019), 5, 1, (23), 10.1038/s41523-019-0115-9"In the original version of this paper, the link to the data record in the Data Availability Statement was incorrectly listed as https:// doi.org/10.6084/m9.figshare.8138912.44. The link has been corrected to https://doi.org/10.6084/m9.figshare.8138912. This has been corrected in the HTML and PDF versions of this article.</p

Publisher Correction: Homologous recombination DNA repair defects in PALB2 -associated breast cancers

An amendment to this paper has been published and can be accessed via a link at the top of the paper

Homologous recombination DNA repair defects in PALB2-associated breast cancers

Abstract Mono-allelic germline pathogenic variants in the Partner And Localizer of BRCA2 (PALB2) gene predispose to a high-risk of breast cancer development, consistent with the role of PALB2 in homologous recombination (HR) DNA repair. Here, we sought to define the repertoire of somatic genetic alterations in PALB2-associated breast cancers (BCs), and whether PALB2-associated BCs display bi-allelic inactivation of PALB2 and/or genomic features of HR-deficiency (HRD). Twenty-four breast cancer patients with pathogenic PALB2 germline mutations were analyzed by whole-exome sequencing (WES, n = 16) or targeted capture massively parallel sequencing (410 cancer genes, n = 8). Somatic genetic alterations, loss of heterozygosity (LOH) of the PALB2 wild-type allele, large-scale state transitions (LSTs) and mutational signatures were defined. PALB2-associated BCs were found to be heterogeneous at the genetic level, with PIK3CA (29%), PALB2 (21%), TP53 (21%), and NOTCH3 (17%) being the genes most frequently affected by somatic mutations. Bi-allelic PALB2 inactivation was found in 16 of the 24 cases (67%), either through LOH (n = 11) or second somatic mutations (n = 5) of the wild-type allele. High LST scores were found in all 12 PALB2-associated BCs with bi-allelic PALB2 inactivation sequenced by WES, of which eight displayed the HRD-related mutational signature 3. In addition, bi-allelic inactivation of PALB2 was significantly associated with high LST scores. Our findings suggest that the identification of bi-allelic PALB2 inactivation in PALB2-associated BCs is required for the personalization of HR-directed therapies, such as platinum salts and/or PARP inhibitors, as the vast majority of PALB2-associated BCs without PALB2 bi-allelic inactivation lack genomic features of HRD

Polygenic risk scores for prediction of breast cancer and breast cancer subtypes

Abstract Stratification of women according to their risk of breast cancer based on polygenic risk scores (PRSs) could improve screening and prevention strategies. Our aim was to develop PRSs, optimized for prediction of estrogen receptor (ER)-specific disease, from the largest available genome-wide association dataset and to empirically validate the PRSs in prospective studies. The development dataset comprised 94,075 case subjects and 75,017 control subjects of European ancestry from 69 studies, divided into training and validation sets. Samples were genotyped using genome-wide arrays, and single-nucleotide polymorphisms (SNPs) were selected by stepwise regression or lasso penalized regression. The best performing PRSs were validated in an independent test set comprising 11,428 case subjects and 18,323 control subjects from 10 prospective studies and 190,040 women from UK Biobank (3,215 incident breast cancers). For the best PRSs (313 SNPs), the odds ratio for overall disease per 1 standard deviation in ten prospective studies was 1.61 (95%CI: 1.57–1.65) with area under receiver-operator curve (AUC) = 0.630 (95%CI: 0.628–0.651). The lifetime risk of overall breast cancer in the top centile of the PRSs was 32.6%. Compared with women in the middle quintile, those in the highest 1% of risk had 4.37- and 2.78-fold risks, and those in the lowest 1% of risk had 0.16- and 0.27-fold risks, of developing ER-positive and ER-negative disease, respectively. Goodness-of-fit tests indicated that this PRS was well calibrated and predicts disease risk accurately in the tails of the distribution. This PRS is a powerful and reliable predictor of breast cancer risk that may improve breast cancer prevention programs