Dataset Information

Association Between Breastfeeding and Ovarian Cancer Risk.

ABSTRACT:

Importance

Breastfeeding has been associated with a reduced risk of epithelial ovarian cancer in multiple studies, but others showed no association. Whether risk reduction extends beyond that provided by pregnancy alone or differs by histotype is unclear. Furthermore, the observed associations between duration and timing of breastfeeding with ovarian cancer risk have been inconsistent.

Objective

To determine the association between breastfeeding (ie, ever/never, duration, timing) and ovarian cancer risk overall and by histotype.

Design, setting, and participants

A pooled analysis of parous women with ovarian cancer and controls from 13 case-control studies participating in the Ovarian Cancer Association Consortium was performed. Odds ratios (ORs) and 95% CIs of the overall association were calculated using multivariable logistic regression and polytomous logistic regression for histotype-specific associations. All data were collected from individual sites from November 1989 to December 2009, and analysis took place from September 2017 to July 2019.

Exposures

Data on breastfeeding history, including duration per child breastfed, age at first and last breastfeeding, and years since last breastfeeding were collected by questionnaire or interview and was harmonized across studies.

Main outcomes and measures

Diagnosis of epithelial ovarian cancer.

Results

A total of 9973 women with ovarian cancer (mean [SD] age, 57.4 [11.1] years) and 13 843 controls (mean [SD] age, 56.4 [11.7] years) were included. Breastfeeding was associated with a 24% lower risk of invasive ovarian cancer (odds ratio [OR], 0.76; 95% CI, 0.71-0.80). Independent of parity, ever having breastfed was associated with reduction in risk of all invasive ovarian cancers, particularly high-grade serous and endometrioid cancers. For a single breastfeeding episode, mean breastfeeding duration of 1 to 3 months was associated with 18% lower risk (OR, 0.82; 95% CI, 0.76-0.88), and breastfeeding for 12 or more months was associated with a 34% lower risk (OR, 0.66; 95% CI, 0.58-0.75). More recent breastfeeding was associated with a reduction in risk (OR, 0.56; 95% CI, 0.47-0.66 for <10 years) that persisted for decades (OR, 0.83; 95% CI, 0.77-0.90 for ≥30 years; P for trend = .02).

Conclusions and relevance

Breastfeeding is associated with a significant decrease in risk of ovarian cancer overall and for the high-grade serous subtype, the most lethal type of ovarian cancer. The findings suggest that breastfeeding is a potentially modifiable factor that may lower risk of ovarian cancer independent of pregnancy alone.

SUBMITTER: Babic A

PROVIDER: S-EPMC7118668 | biostudies-literature |

REPOSITORIES: biostudies-literature

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Project description:OBJECTIVE:Previous studies suggest that breastfeeding reduces epithelial ovarian cancer (EOC) risk. However, the effects of age, timing and episode details on the EOC-breastfeeding relationship have not been examined. The objective of this study was to examine the association between breastfeeding factors and epithelial ovarian cancer. METHODS:We examined breastfeeding factors among parous women in a population-based, case-control study conducted in Pennsylvania, Ohio, and New York from 2003 to 2008. We compared 689 incident EOC cases to 1572 community controls. Multivariable unconditional logistic regression was used to calculate odds ratios (ORs) and 95% confidence intervals (CIs) associated with breastfeeding patterns adjusting for potential confounders. RESULTS:Compared to never breastfeeding, breastfeeding any offspring was associated with a 30% reduction in EOC risk (OR = 0.70; 95%CI = 0.58-0.85). That association lasted more than 30 years (OR = 0.69, 95%CI = 0.53-0.88). An average breastfeeding episode of 3 months was also associated with reduced risk (OR = 0.73, 95%CI = 0.58-0.80). A greater number of breastfeeding episodes was associated with greater risk reduction (OR = 0.78, 95%CI = 0.64-0.96 and OR = 0.49, 95%CI = 0.36-0.68 1-2 and 3+ episodes, respectively, compared to never breastfed, trend p = 0.01). Longer breastfeeding duration was also associated with reduced risk (OR = 0.75 and 0.62 for less than and greater than 1-year total duration, respectively, compared to never breastfed). An earlier age at first breastfeeding was further associated with increased protection (OR = 0.50-0.80, for first episode at age <25, 25-29, and 30+, respectively, trend p = 0.001). CONCLUSIONS:Breastfeeding for as few as 3 months is associated with reduced EOC risk. Although this association decreases over time, it persists for more than 30 years. Longer cumulative duration, increasing number of breastfeeding episodes, and earlier age at first breastfeeding episode are each associated with increased benefit.