How does cancer treatment affect T cells and B cells?

Cancer treatments can affect T cells and B cells in a couple of different ways. 

Traditional cancer treatments such as chemotherapy and radiation therapy work in two ways. They destroy tumor cells directly and also help the immune system become more efficient in recognizing and destroying the tumor. While carrying out these essential treatments to kill the cancer cells, they also lead to a decrease in the number of white blood cells (T cells and B cells), increasing the body’s susceptibility to infections. 

Chemotherapy targets rapidly dividing cells, which encompasses the tumor cells as well as T cells and B cells, which also divide rapidly to replenish themselves. Consequently, patients undergoing chemotherapy treatments often experience a drop in their cell count. Similarly, radiation therapy can also result in a decrease in white blood cell counts. However, once the treatment is stopped, the immune system rebounds and immune cells in the body are replenished, aided by the regenerative capacity of the bone marrow. 

Additionally, these traditional cancer treatments directly kill only some tumor cells. A significant number of tumor cells may remain unaffected. Nevertheless, the dying tumor cells release substances that act as signals for the immune system. T cells, B cells, and other immune components can recognize these signals, potentially prompting an immune response against the remaining tumor cells.