The effects of parity, breastfeeding, and infertility treatment on the risk of hereditary breast and ovarian cancer: a review

Precise, Genotype-First Breast Cancer Prevention: Experience With Transferring Monogenic Findings From a Population Biobank to the Clinical Setting

Although hereditary breast cancer screening and management are well accepted and established in clinical settings, these efforts result in the detection of only a fraction of genetic predisposition at the population level. Here, we describe our experience from a national pilot study (2018–2021) in which 180 female participants of Estonian biobank (of >150,000 participants in total) were re-contacted to discuss personalized clinical prevention measures based on their genetic predisposition defined by 11 breast cancer–related genes. Our results show that genetic risk variants are relatively common in the average-risk Estonian population. Seventy-five percent of breast cancer cases in at-risk subjects occurred before the age of 50 years. Only one-third of subjects would have been eligible for clinical screening according to the current criteria. The participants perceived the receipt of genetic risk information as valuable. Fluent cooperation of project teams supported by state-of-art data management, quality control, and secure transfer can enable the integration of research results to everyday medical practice in a highly efficient, timely, and well-accepted manner. The positive experience in this genotype-first breast cancer study confirms the value of using existing basic genomic data from population biobanks for precise prevention.

Reducing the Risk of Gynecologic Cancer in Hereditary Breast Ovarian Cancer Syndrome Mutation Carriers: Moral Dilemmas and the Principle of Double Effect

Hereditary breast ovarian cancer (HBOC) syndrome is an autosomal dominant disease linked to mutations in the BRCA1 and BRCA2 genes in 90 percent of affected families. Female mutation carriers are highly susceptible to aggressive, often disseminated, usually fatal pelvic-abdominal carcinomatosis. This cancer risk can be markedly reduced by surgical removal of the internal gynecologic organs before the end of the fourth decade of life and by using estrogen-progestin formulations marketed for many years as combined oral contraceptives (COCs). Both risk-reducing methods are associated with unfavorable effects. Relying on the principle of double effect, this essay argues for the ethical justification of prophylactic surgery and the use of COC to reduce the risk of gynecologic cancer in HBOC syndrome mutation carriers. Summary: Hereditary breast ovarian cancer syndrome is an autosomal dominant disease linked to mutations in the BRCA1 and BRCA2 genes in most affected families. Female mutation carriers are highly susceptible to aggressive, often disseminated, usually fatal pelvic-abdominal carcinomatosis. This cancer risk can be markedly reduced by surgical removal of the internal gynecologic organs before the end of the fourth decade of life and by using estrogen-progestin formulations marketed for many years as combined oral contraceptives. Both risk-reducing methods are associated with unfavorable effects. Relying on the principle of double effect, this essay argues for the ethical justification for those unfavorable effects.

The Effect of Breastfeeding Duration and Parity on the Risk of Epithelial Ovarian Cancer: A Systematic Review and Meta-analysis

Objectives

We conducted a systematic review and meta-analysis to summarize current evidence regarding the association of parity and duration of breastfeeding with the risk of epithelial ovarian cancer (EOC).

Methods

A systematic search of relevant studies published by December 31, 2015 was performed in PubMed and EMBASE. A random-effect model was used to obtain the summary relative risks (RRs) and 95% confidence intervals (CIs).

Results

Thirty-two studies had parity categories of 1, 2, and ≥3. The summary RRs for EOC were 0.72 (95% CI, 0.65 to 0.79), 0.57 (95% CI, 0.49 to 0.65), and 0.46 (95% CI, 0.41 to 0.52), respectively. Small to moderate heterogeneity was observed for one birth (p<0.01; Q=59.46; I²=47.9%). Fifteen studies had breastfeeding categories of <6 months, 6-12 months, and >13 months. The summary RRs were 0.79 (95% CI, 0.72 to 0.87), 0.72 (95% CI, 0.64 to 0.81), and 0.67 (95% CI, 0.56 to 0.79), respectively. Only small heterogeneity was observed for <6 months of breastfeeding (p=0.17; Q=18.79, I²=25.5%). Compared to nulliparous women with no history of breastfeeding, the joint effects of two births and <6 months of breastfeeding resulted in a 0.5-fold reduced risk for EOC.

Conclusions

The first birth and breastfeeding for <6 months were associated with significant reductions in EOC risk.

Fertility treatments and invasive epithelial ovarian cancer risk in Jewish Israeli BRCA1 or BRCA2 mutation carriers

OBJECTIVE

To determine whether BRCA mutation carriers who undergo fertility treatments are at increased risk of developing invasive epithelial ovarian cancer (IEOC).

DESIGN

Historical cohort study.

SETTING

Tertiary university-affiliated medical center and the National Cancer Registry.

PATIENT(S)

A total of 1,073 Jewish Israeli BRCA mutation carriers diagnosed in a single institution between 1995 and 2013, including 164 carriers (15.2%) who had fertility treatments that included clomiphene citrate (n = 82), gonadotropin (n = 69), in vitro fertilization (IVF) (n = 66), or a combination (n = 50), and 909 carriers not treated for infertility.

INTERVENTION(S)

None.

MAIN OUTCOME MEASURE(S)

Odds ratios (OR) and 95% confidence intervals (CI) for IEOC association with fertility treatments and other hormone and reproductive variables.

RESULT(S)

In 175 (16.3%) mutation carriers, IEOC was diagnosed; 139 women carried BRCA1, 33 carried BRCA2, and 3 had unknown mutations. Fertility treatments were not associated with IEOC risk (age-adjusted OR 0.63; 95% CI, 0.38-1.05) regardless of treatment type (with clomiphene citrate, OR 0.87; 95% CI, 0.46-1.63; with gonadotropin, OR 0.59; 95% CI, 0.26-1.31; with IVF, OR 1.08, 95% CI, 0.57-2.06). Multivariate analysis indicated an increased risk of IEOC with hormone-replacement therapy (OR 2.22; 95% CI, 1.33-3.69) and a reduced risk with oral contraceptives (OR 0.19; 95% CI, 0.13-0.28) in both BRCA1 and BRCA2 mutation carriers. Parity was a risk factor for IEOC by univariate but not multivariate analysis.

CONCLUSION(S)

According to our results, treatments for infertile BRCA mutation carriers should not be contraindicated or viewed as risk modifiers for IEOC. Parity as a risk factor in BRCA mutation carriers warrants further investigation.