The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic focus primarily on assessment of pathogenic or likely pathogenic variants associated with increased risk of breast, ovarian, and pancreatic cancer and recommended approaches to genetic testing/counseling and management strategies in individuals with these pathogenic or likely pathogenic variants. This manuscript focuses on cancer risk and risk management for BRCA-related breast/ovarian cancer syndrome and Li-Fraumeni syndrome. Carriers of a BRCA1/2 pathogenic or likely pathogenic variant have an excessive risk for both breast and ovarian cancer that warrants consideration of more intensive screening and preventive strategies. There is also evidence that risks of prostate cancer and pancreatic cancer are elevated in these carriers. Li-Fraumeni syndrome is a highly penetrant cancer syndrome associated with a high lifetime risk for cancer, including soft tissue sarcomas, osteosarcomas, premenopausal breast cancer, colon cancer, gastric cancer, adrenocortical carcinoma, and brain tumors.

The NCCN Clinical Practice Guidelines in Oncology for Genetic/Familial High-Risk Assessment: Breast and Ovarian provide recommendations for genetic testing and counseling for hereditary cancer syndromes and risk management recommendations for patients who are diagnosed with a syndrome. Guidelines focus on syndromes associated with an increased risk of breast and/or ovarian cancer. The NCCN Genetic/Familial High-Risk Assessment: Breast and Ovarian panel meets at least annually to review comments from reviewers within their institutions, examine relevant new data from publications and abstracts, and reevaluate and update their recommendations. The NCCN Guidelines Insights summarize the panel's discussion and most recent recommendations regarding risk management for carriers of moderately penetrant genetic mutations associated with breast and/or ovarian cancer.

The NCCN Guidelines for Genetic/Familial High-Risk Assessment: Breast, Ovarian, and Pancreatic provide recommendations for genetic testing and counseling for hereditary cancer syndromes, and risk management recommendations for patients who are diagnosed with syndromes associated with an increased risk of these cancers. The NCCN panel meets at least annually to review comments, examine relevant new data, and reevaluate and update recommendations. These NCCN Guidelines Insights summarize the panel’s discussion and most recent recommendations regarding criteria for high-penetrance genes associated with breast and ovarian cancer beyond BRCA1/2, pancreas screening and genes associated with pancreatic cancer, genetic testing for the purpose of systemic therapy decision-making, and testing for people with Ashkenazi Jewish ancestry.

Although it is well established that women with germ-line mutations in the BRCA1 gene have a greatly increased lifetime incidence of breast and ovarian cancer, the molecular mechanisms responsible for this tissue-specific carcinogenesis remain undefined. The majority of these breast cancers are of the basal-like phenotype characterized by lack of expression of ER, PR, and ERBB2. Because this phenotype has been proposed to resemble that of normal breast stem cells, we examined the role of BRCA1 in human mammary stem cell fate. Using both in vitro systems and a humanized NOD/SCID mouse model, we demonstrate that BRCA1 expression is required for the differentiation of ER-negative stem/ progenitor cells to ER-positive luminal cells. Knockdown of BRCA1 in primary breast epithelial cells leads to an increase in cells displaying the stem/progenitor cell marker ALDH1 and a decrease in cells expressing luminal epithelial markers and estrogen receptor. In breast tissues from women with germ-line BRCA1 mutations, but not normal controls, we detect entire lobules that, although histologically normal, are positive for ALDH1 expression but are negative for the expression of ER. Loss of heterozygosity for BRCA1 was documented in these ALDH1-positive lobules but not in adjacent ALDH1-negative lobules. Taken together, these studies demonstrate that BRCA1 plays a critical role in the differentiation of ER-negative stem/progenitor cells to ER-positive luminal cells. Because BRCA1 also plays a role in DNA repair, our work suggests that loss of BRCA1 may result in the accumulation of genetically unstable breast stem cells, providing prime targets for further carcinogenic events.breast cancer ͉ stem cell ͉ hereditary cancer A ccumulating evidence has provided support for the cancer stem cell hypothesis, which holds that cancers originate in tissue stem and/or progenitor cells through the dysregulation of self-renewal processes. The ensuing tumors are driven by a cellular subcomponent that retains stem cell properties (1). Evidence for a cancer stem cell component has been generated in human breast cancers (2), as well as cancers of hematopoietic and solid tumor origin (3-6). A number of developmental pathways such as NOTCH (7), Hedgehog (8,9), and Wnt (9, 10) have been shown to be involved in the regulation of self-renewal and the differentiation of stem and progenitor cells in a number of cell types. Furthermore, these pathways are frequently dysregulated during carcinogenesis (9-13). It is not known whether genes that contribute to hereditary cancers play a role in regulating stem cell fate. Heterozygous germ-line mutations in the BRCA1 gene predispose women to breast and ovarian cancer with a lifetime risk of breast cancer of up to 85% (14). The vast majority of breast tumors in these patients display a basal-like phenotype characterized by a lack of expression of ER, PR, and ERBB2, but robust expression of markers of myoepithelial differentiation (15). Mouse models using conditional BRCA1 KOs have suggested an important role for ...

Breast carcinoma is the most common malignancy among women in developed countries. Because family history remains the strongest single predictor of breast cancer risk, attention has focused on the role of highly penetrant, dominantly inherited genes in cancer-prone kindreds (1). BRCA1 was localized to chromosome 17 through analysis of a set of high-risk kindreds (2), and then identified four years later by a positional cloning strategy (3). BRCA2 was mapped to chromosomal 13q at about the same time (4). Just fifteen months later, Wooster et al. (5) reported a partial BRCA2 sequence and six mutations predicted to cause truncation of the BRCA2 protein. While these findings provide strong evidence that the identified gene corresponds to BRCA2, only two thirds of the coding sequence and 8 out of 27 exons were isolated and screened; consequently, several questions remained unanswered regarding the nature of BRCA2 and the frequency of mutations in 13q-linked families. We have now determined the complete coding sequence and exonic structure of BRCA2 (GenBank accession #U43746), and examined its pattern of expression. Here, we provide sequences for a set of PCR primers sufficient to screen the entire coding sequence of BRCA2 using genomic DNA. We also report a mutational analysis of BRCA2 in families selected on the basis of linkage analysis and/or the presence of one or more cases of male breast cancer. Together with the specific mutations described previously, our data provide preliminary insight into the BRCA2 mutation profile.