Familial concordance of breast cancer pathology as an indicator of genotype in multiple-case families

Impact of Prophylactic Mastectomy in BRCA1/2 Mutation Carriers

Unlike the general decrease in invasive oncologic care, the trend for prophylactic bilateral mastectomy in healthy women and prophylactic contralateral mastectomy in women with unilateral breast cancer is steadily rising. This is even more surprising when considering that for e.g. prophylactic contralateral mastectomy no clear survival benefit has been demonstrated so far. The decision-making process around risk-reducing surgery may be influenced by several conflicting parameters such as the patient's fears and desire to achieve a survival advantage, the surgeon's financial motivations, or the oncologist's paternalistic approach to the above trend. Physicians should support their patients throughout the decision-making process, guide them through the dense fog of information, and encourage them to reconsider all options and alternatives before embarking on an irreversible surgical intervention. Healthy and diseased women should be comprehensively informed about their absolute individual risks for cancer, the benefits and harms of the surgery, alternative preventive strategies, and last but not least the competing risks of preceding carcinomas and cancer in general. Within the framework of non-directive counseling in the specialized centers of the German Consortium for Hereditary Breast and Ovarian Cancer (GC-HBOC), decision-making aids are being developed with grants from the Federal Ministry of Health and the German Cancer Aid to support women in making conclusive and satisfactory decisions.

The complex genetic landscape of familial breast cancer

Familial breast cancer represents a minor percentage of all human breast cancers. Mutations in two high susceptibility genes BRCA1 and BRCA2 explain around 25 % of familial breast cancers, while other high, moderate and low susceptibility genes explain up to 20 % more of breast cancer families. Thus, it is important to decipher the genetic architecture of families that show no mutations to improve genetic counselling. The comprehensive description of familial breast cancer using different techniques and platforms has shown to be very valuable for better patient diagnosis, tumour surveillance, and ultimately patient treatment. This review focuses on the complex landscape of pathological, protein, genetic and genomic features associated with BRCA1-, BRCA2-, and non-BRCA1/BRCA2-related cancers described up to date. Special emphasis deserves the coexistence of distinct molecular breast cancer subtypes, the development of tumour classifiers to predict BRCA1/2 mutations, and the last insights from recent whole genome sequencing studies and miRNA profiling.

Phenotype-genotype correlation in familial breast cancer

Familial breast cancer accounts for a small but significant proportion of breast cancer cases worldwide. Identification of the candidate genes is always challenging specifically in patients with little or no family history. Therefore, a multidisciplinary team is required for the proper detection and further management of these patients. Pathologists have played a pivotal role in the cataloguing of genotypic-phenotypic correlations in families with hereditary cancer syndromes. These efforts have led to the identification of histological and phenotypic characteristics that can help predict the presence or absence of germline mutations of specific cancer predisposition genes. However, the panoply of cancer phenotypes associated with mutations of genes other than in BRCA1 is yet to be fully characterised; in fact, many cancer syndromes, germline mutations and gene sequence variants are under investigation for their possible morphological associations. Here we review the current understanding of phenotype-genotype correlation in familial breast cancer.