Parity and lactation induce T cell mediated breast cancer protection

"Parity and breastfeeding reduce the risk of breast cancer, particularly triple-negative breast cancer (TNBC)1,2, yet the immunological mechanisms underlying this protection remain unclear. Here, we show that parity induces an accumulation of CD8+ T cells, including cells with a tissue-resident memory (TRM)-like phenotype within human normal breast tissue. In murine models, pregnancy followed by lactation and involution drove the accumulation of CD8 T"

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Parity and breastfeeding reduce the risk of breast cancer, particularly triple-negative breast cancer (TNBC). The immunological mechanisms underlying this protection remain unclear. Parity induces an accumulation of CD8+ T cells, including cells with a tissue-resident memory (TRM)-like phenotype within human normal breast tissue. In murine models, pregnancy followed by lactation and involution drove accumulation of CD8 T cells. These observations indicate that reproductive events reshape local breast immune composition, enriching cytotoxic and tissue-resident memory-like CD8 populations. The accumulation of CD8+ TRM-like cells provides a plausible immune correlate of parity-associated protection against aggressive breast cancer subtypes.

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