Impact of a paternal origin of germlineBRCA1/2 mutations on the age at breast and ovarian cancer diagnosis in a Southern Swedish cohort

Fertility treatments and breast cancer risk in Jewish Israeli BRCA mutation carriers

OBJECTIVE

To determine whether fertility treatments impact the risk of breast cancer in Jewish Israeli BRCA1/2 mutation carriers.

DESIGN

Historical cohort study.

SETTING

University-affiliated tertiary medical center.

PATIENT(S)

A total of 1,824 Jewish Israeli BRCA1/2 mutation carriers from a single center were stratified into 1,492 (81.8%) carriers who were not treated for infertility and 332 (18.2%) carriers who underwent fertility treatment with clomiphene citrate (n = 134), gonadotropin (n = 119), in vitro fertilization (n = 183), or a combination of treatments (n = 89).

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Hazard ratios (HR) and 95% confidence intervals (CI) for the association of breast cancer with fertility treatment and other hormonal and reproductive variables.

RESULT(S)

Breast cancer was diagnosed in 687 BRCA1/2 mutation carriers. Multivariate analysis, either of the whole group or stratified by each gene, showed no association between fertility treatment and breast cancer risk, regardless of the type of treatment (clomiphene citrate: HR 0.77, 95% CI 0.49-1.19; gonadotropin: HR 0.54, 95% CI 0.28-1.01; in vitro fertilization: HR 0.65, 95% CI 0.39-1.08; and combined treatments: HR 1.23, 95% CI 0.49-3.06). An increased breast cancer risk was associated with paternal origin of the mutation (HR 1.43, 95% CI 1.17-1.75) and use of oral contraceptives for >5 years (HR 1.62, 95% CI 1.27-2.06) in both BRCA1 and BRCA2 mutation carriers. Ovarian cancer risk was decreased with the use of any oral contraceptive (HR 0.61; 95% CI 0.46-0.82).

CONCLUSION(S)

Fertility treatment for BRCA1/2 mutation carriers is not associated with a discernible increase in breast cancer risk.

Parent of Origin Effects on Family Communication of Risk in BRCA+ Women: A Qualitative Investigation of Human Factors in Cascade Screening

Pathogenic germline variants in Breast Cancer 1/2 (BRCA) genes confer increased cancer risk. Understanding BRCA status/risk can enable family cascade screening and improve cancer outcomes. However, more than half of the families do not communicate family cancer history/BRCA status, and cancer outcomes differ according to parent of origin (i.e., maternally vs. paternally inherited pathogenic variant). We aimed to explore communication patterns around family cancer history/BRCA risk according to parent of origin. We analyzed qualitative interviews (n = 97) using template analysis and employed the Theory of Planned Behavior (TPB) to identify interventions to improve communication. Interviews revealed sub-codes of ‘male stoicism and ‘paternal guilt’ that impede family communication (template code: gender scripting). Conversely, ‘fatherly protection’ and ‘female camaraderie’ promote communication of risk. The template code ‘dysfunctional family communication’ was contextualized by several sub-codes (‘harmful negligence’, ‘intra-family ignorance’ and ‘active withdrawal of support’) emerging from interview data. Sub-codes ‘medical misconceptions’ and ‘medical minimizing’ deepened our understanding of the template code ‘medical biases’. Importantly, sub-codes of ‘informed physicians’ and ‘trust in healthcare’ mitigated bias. Mapping findings to the TPB identified variables to tailor interventions aimed at enhancing family communication of risk and promoting cascade screening. In conclusion, these data provide empirical evidence of the human factors impeding communication of family BRCA risk. Tailored, theory-informed interventions merit consideration for overcoming blocked communication and improving cascade screening uptake.

Parent of origin differences in psychosocial burden and approach to BRCA risk management

We conducted a mixed-method study to examine coping response in BRCA+ women based on parent of origin (maternally vs paternally inherited BRCA mutation). Quantitative findings (n = 408) revealed paternally inherited cases had genetic testing later and were more likely to have a cancer diagnosis. Having a maternally inherited mutation was the strongest predictor of proactive risk management response. Qualitative interviews (n = 56) identified proactive responses among maternally inherited cases compared to reactive responses in paternally inherited cases. Findings underscore the importance of unbiased pedigree analysis to determine cancer risk. Women with paternally inherited BRCA mutations may benefit from additional psychosocial support.

Differential expression of parental alleles of BRCA1 in human preimplantation embryos

Gene expression from both parental genomes is required for completion of embryogenesis. Differential methylation of each parental genome has been observed in mouse and human preimplantation embryos. It is possible that these differences in methylation affect the level of gene transcripts from each parental genome in early developing embryos. The aim of this study was to investigate if there is a parent-specific pattern of BRCA1 expression in human embryos and to examine if this affects embryo development when the embryo carries a BRCA1 or BRCA2 pathogenic mutation. Differential parental expression of ACTB, SNRPN, H19 and BRCA1 was semi-quantitatively analysed by minisequencing in 95 human preimplantation embryos obtained from 15 couples undergoing preimplantation genetic diagnosis. BRCA1 was shown to be differentially expressed favouring the paternal transcript in early developing embryos. Methylation-specific PCR showed a variable methylation profile of BRCA1 promoter region at different stages of embryonic development. Embryos carrying paternally inherited BRCA1 or 2 pathogenic variants were shown to develop more slowly compared with the embryos with maternally inherited BRCA1 or 2 pathogenic mutations. This study suggests that differential demethylation of the parental genomes can influence the early development of preimplantation embryos. Expression of maternal and paternal genes is required for the completion of embryogenesis.

Bias Explains Most of the Parent-of-Origin Effect on Breast Cancer Risk in BRCA1/2 Mutation Carriers

BACKGROUND

Paternal transmission of a BRCA mutation has been reported to increase the risk of breast cancer in offspring more than when the mutation is maternally inherited. As this effect might be caused by referral bias, the aim of this study was to assess the parent-of-origin effect of the BRCA1/2 mutation on the breast cancer lifetime risk, when adjusted for referral bias.

METHODS

A Dutch national cohort including 1,314 proven BRCA1/2 mutation carriers and covering 54,752 person years. Data were collected by family cancer clinics, via questionnaires and from the national Dutch Cancer Registry. The parent-of-origin effect was assessed using Cox regression analyses, both unadjusted and adjusted for referral bias. Referral bias was operationalized by number of relatives with cancer and by personal cancer history.

RESULTS

The mutation was of paternal origin in 330 (42%, P < 0.001) BRCA1 and 222 (42%, P < 0.001) BRCA2 carriers. Paternal origin increased the risk of prevalent breast cancer for BRCA1 [HR, 1.54; 95% confidence interval (CI), 1.19-2.00] and BRCA2 carriers (HR, 1.40; 95% CI, 0.95-2.06). Adjusted for referral bias by several family history factors, these HRs ranged from 1.41 to 1.83 in BRCA1 carriers and 1.27 to 1.62 in BRCA2 carriers. Adjusted for referral bias by personal history, these HRs were 0.66 (95% CI, 0.25-1.71) and 1.14 (95% CI, 0.42-3.15), respectively.

CONCLUSION

A parent-of-origin effect is present after correction for referral bias by family history, but correction for the personal cancer history made the effect disappear.

IMPACT

There is no conclusive evidence regarding incorporating a BRCA1/2 parent-of-origin effect in breast cancer risk prediction models. Cancer Epidemiol Biomarkers Prev; 25(8); 1251-8. ©2016 AACR.