Breastfeeding and the Risk of Ovarian Cancer Among Women with BRCA Mutations

CQ #210 – November 9, 2020
by Anne Eglash MD, IBCLC, FABM
#LACTFACT
Breastfeeding is associated with a decreased risk of ovarian cancer among women with the BRCA1 or BRCA2 mutation.
Gynecologic Oncology online Sept 30th 2020

Do women with the BRCA1 or BRCA2 gene mutations have a lower risk of ovarian cancer if they breastfeed?

Several well-designed studies, including at least 1 meta-analysis have concluded that breastfeeding is associated with a decreased risk of ovarian cancer. I reviewed a large meta-analysis on this topic in a CQW published in June 2019.

The question is whether breastfeeding also reduces the risk of ovarian cancer among women with the Breast Cancer Genes, AKA BRCA1 and BRCA2.

The recent article for this week’s CQW is an international study that included women with known BRCA1 or BRCA2 mutation, from 61 participating centers in 15 countries. These women sought genetic testing due to a family history of breast and/or ovarian cancer, or a personal history of breast cancer. Data collected included history of pregnancies/birthing, ever vs never breastfed, number of months they had breastfed, and contraception use. Approximately 2000 control subjects with BRCA1 or BRCA2 were matched with 1650 case subjects who developed ovarian cancer. The average age at time of diagnosis was 52 years.

The researchers found that the control group had significantly higher cumulative duration of breastfeeding (14.5 months) as compared to the women who developed ovarian cancer (13 months).

What do you think are other accurate statements regarding the association of ovarian cancer and breastfeeding among subjects with the BRCA1 and BRCA2 mutations, based on this data? Choose 1 or more:
  1. Subjects who developed ovarian cancer were less likely to ever breastfeed.
  2. Ever-breastfeeding was associated with a 23% reduction in the risk of ovarian cancer.
  3. The longer a subject breastfed, the lower her risk of ovarian cancer, up until 7 months. Breastfeeding beyond 7 months did not add further protection.
  4. Breastfeeding was associated with a greater risk reduction of ovarian cancer for women who completed childbearing under age 35 vs women who gave birth to an infant at age 35 or older.
  5. Women who had a history of both breastfeeding and oral contraceptive use had the lowest risk for ovarian cancer.

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