Breastfeeding alleviates the risk of Ovarian Cancer

Multiple studies have shown an association between breastfeeding and a reduced risk of epithelial ovarian Cancer. However, it remains unclear whether this risk reduction extends beyond pregnancy alone or varies by histotype. Furthermore, the observed links between the duration and timing of breastfeeding with ovarian cancer risk remain inconsistent.

The present study determined the association between breastfeeding (i.e., ever/never, duration, timing) and ovarian cancer risk overall and by histotype.

The study performed a pooled analysis of parous women with ovarian Cancer from 13 studies participating in the Ovarian Cancer Association Consortium. It collected data on breastfeeding history, including duration per child, breastfed, age at first and last breastfeeding, and years since last breastfeeding via questionnaire or interview and looked for the diagnosis of epithelial ovarian Cancer.

The study observed-

• Inclusion of 9973 women with ovarian Cancer (mean [SD] age, 57.4 [11.1] years) and 13843 controls (mean [SD] age, 56.4 [11.7] years).
• Breastfeeding caused a 24% lower risk of invasive ovarian Cancer. 
• Independent of parity, ever having breastfed reduced the risk of all invasive ovarian cancers, particularly high-grade serous and endometrioid cancers. 
• For a single breastfeeding episode, a mean breastfeeding duration of 1 to 3 months showed an 18% lower risk and breastfeeding for 12 or more months showed a 34% lower risk. 
• More recent breastfeeding caused risk reduction that persisted for decades.

This study shows that breastfeeding causes a significant decrease in the risk of ovarian cancer overall and for the high-grade serous subtype, the most lethal type of ovarian Cancer. Hence, breastfeeding is a potentially modifiable factor that may diminish the risk of ovarian cancer independent of pregnancy alone.

Babic A, Sasamoto N, Rosner BA, et al. Association Between Breastfeeding and Ovarian Cancer Risk. JAMA Oncol. 2020;6(6):e200421. doi:10.1001/jamaoncol.2020.0421