What happens to the immune system during cancer?

Compromised: The immune system is frequently affected by chemotherapy. The risk of infections goes up.

Depressed: Some cancers and some cancer treatments depress the immune system.

It’s complicated! : The immune system has some “killer” cells that attack cancer, and “suppressor” cells that stop the attack. Tumors can actually turn on the “suppressor” cells that stop the immune attack against them, like putting a brake on. Some types of chemotherapy can actually activate the immune system by knocking out the suppressor cells. Other chemotherapy can decrease the immune system. Hope that helps!

Technically, nothing happens. Successful cancers are often able to evade immune system responses by inactivating immune cells by flashing a molecular badge. T-cells that monitor our tissues will attack foreign cells but can be called off by the correct molecular interaction (PDL1). Since cancer cells are derived from our own cells, they are able to avoid the immune system.