Oral Presentation ESA-SRB-ANZOS 2025 in conjunction with ENSA

A potential biological link between lactational mastitis and risk of breast cancer (127894)

Reza Maleki 1 2 , Amna Ghith 1 2 , Luke Grzeskowiak 3 4 , Wendy Ingman 1 2
  1. Basil Hetzel Institute for Translational Health Research, The Queen Elizabeth Hospital, Woodville South, South Australia, Australia
  2. Robinson Research Institute, The University of Adelaide, Adelaide, South Australia, Australia
  3. College of Medicine and Public Health, Flinders Health and Medical Research Institute,, Flinders University, Bedford Park, South Australia, Australia
  4. SAHMRI Women and Kids, South Australian Health and Medical Research Institute,, Women’s and Children’s Hospital, North Adelaide, South Australia, Australia

Aims: There is an emerging body of epidemiological literature suggesting that mastitis is associated with increased risk of breast cancer, however little is understood of the underlying biology that could link these two breast conditions (1). Interestingly, the association appears to be independent of the breast in which mastitis occurred, suggesting there may be factors that increase risk of both conditions, rather than mastitis having a causal effect on breast cancer risk (2). The aim of this study was to investigate whether factors in breastmilk may mediate this association.

Methods: Breastmilk samples from healthy multiparous women with a history of mastitis whilst feeding a previous infant (high-risk; n=10) and no history of mastitis (low-risk; n=10) were cultured at 100 µg/ml with breast cancer and macrophage cell lines (MDA-MB-231 and RAW264.7, respectively). RT-qPCR was used to assess the expression of proinflammatory genes in macrophages and epithelial–mesenchymal transition (EMT) markers in breast cancer cells. To evaluate crosstalk activity, breast cancer cells were treated with conditioned media from macrophages treated with breastmilk, followed by analysis of EMT markers, cell viability, wound healing, transwell migration, and invasion assays.

Results: Despite high variability in gene expression in macrophages treated with individual breastmilk samples, high-risk breastmilk induced overall higher expression of proinflammatory markers in macrophages compared to low-risk breastmilk (p = 0.001). Breast cancer cells treated with macrophage-conditioned media derived from selected high-risk breastmilk exhibited increased mesenchymal marker CDH2, enhanced cell viability, migration, and invasion.

Conclusion: This study suggests there may be factors in breastmilk from women with a history of mastitis that indirectly promote breast cancer development and progression through macrophage-mediated mechanisms. Further research is required to explore the potential biological association between mastitis and breast cancer risk.

  1. 1. Krishnan VD, Kostev K, Kalder M. Is there an association between mastitis and breast cancer? a retrospective cohort study from Germany. Cancer Causes Control. 2024;35(12):1517-23.
  2. 2. Ingman WV, Glynn DJ, Hutchinson MR. Inflammatory mediators in mastitis and lactation insufficiency. J Mammary Gland Biol Neoplasia. 2014;19(2):161-7.