Association Between Breastfeeding and Ovarian Cancer Risk

Ana Babic; Naoko Sasamoto; Bernard A Rosner; Shelley S Tworoger; Susan J Jordan; Harvey A Risch; Holly R Harris; Mary Anne Rossing; Jennifer A Doherty; Renée T Fortner; Jenny Chang-Claude; Marc T Goodman; Pamela J Thompson; Kirsten B Moysich; Roberta B Ness; Susanne K Kjaer; Allan Jensen; Joellen M Schildkraut; Linda J Titus; Daniel W Cramer; Elisa V Bandera; Bo Qin; Weiva Sieh; Valerie McGuire; Rebecca Sutphen; Celeste L Pearce; Anna H Wu; Malcolm Pike; Penelope M Webb; Francesmary Modugno; Kathryn L Terry

doi:10.1001/jamaoncol.2020.0421

Association Between Breastfeeding and Ovarian Cancer Risk

Babic A, Sasamoto N, Rosner BA, Tworoger SS, Jordan SJ, Risch HA, Harris HR, Rossing MA, Doherty JA, Fortner RT, Chang-Claude J, Goodman MT, Thompson PJ, Moysich KB, Ness RB, Kjaer SK, Jensen A, Schildkraut JM, Titus LJ, Cramer DW, Bandera EV, Qin B, Sieh W, McGuire V, Sutphen R, Pearce CL, Wu AH, Pike M, Webb PM, Modugno F, Terry KL

Published June 2020 JAMA oncology, 6(6), e200421

DOI 10.1001/jamaoncol.2020.0421 PMID 32239218 PMC PMC7118668

RRM Academy Synopsis

Breastfeeding is associated with lower epithelial ovarian cancer risk

A pooled analysis of 13 case-control studies of mothers found that women who had breastfed had a 24% lower risk of invasive ovarian cancer than women who had not. The pool held 13 843 controls and 9973 women with ovarian cancer. Longer breastfeeding per child went with lower risk.

Key Findings

Invasive ovarian cancer was less common in women who had breastfed (odds ratio 0.76, 95% CI 0.71-0.80), as were borderline tumors (odds ratio 0.72, 95% CI 0.64-0.81).
Three tumor types had statistically significant lower risk: high-grade serous (odds ratio 0.75, 95% CI 0.70-0.81), endometrioid (odds ratio 0.73, 95% CI 0.64-0.84), and clear cell (odds ratio 0.78, 95% CI 0.64-0.96).
In women with a single birth, breastfeeding went with 14% lower risk of invasive disease (odds ratio 0.86, 95% CI 0.75-0.99).
Breastfeeding under 3 months per child went with 18% lower risk (odds ratio 0.82, 95% CI 0.76-0.88). Twelve months or longer went with 34% lower risk (odds ratio 0.66, 95% CI 0.58-0.75).
Women whose last breastfeeding ended less than 10 years earlier had 44% lower risk (odds ratio 0.56, 95% CI 0.47-0.66). The lower risk faded with time yet lasted for decades.

Interpretation

The study pools 13 population-based case-control studies. Women reported their own breastfeeding history, so the results describe associations. Analyses by number of births let the authors examine breastfeeding apart from parity. Most participants were white, and the authors say the data could not fully assess black women, Asian women, and other groups. They ask for larger studies in other racial and ethnic groups.

RRM Context

Lactation is a normal phase of a woman's reproductive life, and restorative reproductive medicine works with the body's own cycles. The authors name ovulation suppression during breastfeeding as the leading idea. They add that the stronger link with longer breastfeeding points to other routes, such as inflammation or metabolism.

Our editorial summary of this paper, not the article's abstract.

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.

Topics

General Gynecology

Gynecologic Oncology Ovarian Cancer

General Gynecology › Gynecologic Oncology › Ovarian Cancer

Ana Babic, Naoko Sasamoto, Bernard A Rosner, Shelley S Tworoger, Susan J Jordan, Harvey A Risch, Holly R Harris, Mary Anne Rossing, Jennifer A Doherty, Renée T Fortner, Jenny Chang-Claude, Marc T Goodman, Pamela J Thompson, Kirsten B Moysich, Roberta B Ness, Susanne K Kjaer, Allan Jensen, Joellen M Schildkraut, Linda J Titus, Daniel W Cramer, Elisa V Bandera, Bo Qin, Weiva Sieh, Valerie McGuire, Rebecca Sutphen, Celeste L Pearce, Anna H Wu, Malcolm Pike, Penelope M Webb, Francesmary Modugno, Kathryn L Terry

A Babic, N Sasamoto, B Rosner, S Tworoger, Sue Jordan, S Jordan, H Risch, H Harris, M Rossing, Jen Doherty, Jenny Doherty, J Doherty, R Fortner, Jennifer Chang-Claude, J Chang-Claude, M Goodman, P Thompson, K Moysich, R Ness, S Kjaer, A Jensen, J Schildkraut, L Titus, Dan Cramer, Danny Cramer, D Cramer, E Bandera, B Qin, W Sieh, V McGuire, Becky Sutphen, R Sutphen, C Pearce, A Wu, M Pike, P Webb, F Modugno, Kathy Terry, Kate Terry, K Terry

PMID 32239218 32239218 DOI 10.1001/jamaoncol.2020.0421 10.1001/jamaoncol.2020.0421 Babic et al. 2020, Babic 2020

Association Between Breastfeeding and Ovarian Cancer Risk

Breastfeeding is associated with lower epithelial ovarian cancer risk

Key Findings

Interpretation

RRM Context

Abstract

Topics

By this author

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