Heightened Risk of Breast Cancer Following Pregnancy: Could Lasting Systemic Immune Alterations Contribute?
This one gets a little deep. Many realize that pregnancy lowers your risk of developing breast cancer. What many do not know is that this is long term risk–in the short term the risk is actually elevated. So why the discrepancy? I have heard the theory proposed that the high levels of progesterone in pregnancy actually increase the risk of terminal duct lobular carcinoma of the breast, but lower the risk of interlobular ductal breast cancer.
This article is suggesting a different (or complimentary) theory. We know that pregnancy induces a change in immune status towards a Th2 dominated state. With a Th2 immune profile, the body is less likely to look inside for something to attack (like the developing fetus). However, we use this system for cancer surveillance. This may indicate that a Th2 state during pregnancy would leave cancer cells to divide unchecked by the immune system, leading to increased rates of cancer.