Understanding the temporarily increased risk of breast cancer on ceasing breast-feeding
In addition to a bundle of joy, pregnancy and childbirth bring major changes to the body, but many aspects revert to their original state afterwards. Once any breastfeeding is done, the milk-producing mammary gland steps back through a carefully controlled course of cell death and resource reallocation. During this process, called involution, women have a temporarily increased risk of breast cancer. To investigate why, researchers took mouse glands at different stages of the process (pink, after one day, with immune cells in blue) and implanted tumour cells. Tumours injected at day 3 of involution grew faster than in mice that had never given birth, but those implanted at day 6 grew more slowly. Unpicking these details will help understand the increased risk. The study also found changes in immune cell activity during the process, which may have significance for the use of anti-inflammatory treatments for breast cancers in new mothers.
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