Overview
- In analyses of healthy tissue from about 260 women, those who had given birth showed higher levels of specialised CD8+ T cells that can persist for decades.
- Mouse experiments found tumours grew more slowly after a full cycle of pregnancy, lactation and involution, with the benefit lost when T cells were depleted.
- The study reported that lactation-associated immunity appeared both local to the breast and systemic in mouse models.
- Clinical data from more than 1,000 women with triple-negative breast cancer showed prior breastfeeding correlated with higher tumour T-cell density and longer overall survival.
- Researchers say the findings shift emphasis from hormones to adaptive immunity and could inform vaccines or therapies, while cautioning breastfeeding is not a guarantee against cancer.