It's because chemo kills fast-growing cells, whether they're cancer or normal cells.

Hair follicles are fast-growing cells.

The particles disperse through the body and first destroy fast-growing cells, like those in bone marrow, blood, hair and the digestive tract.

Chemotherapy affects fast-growing cells and is used to treat cancer because cancer cells grow and divide quickly.

These treatments affect fast-growing cells, such as cancer cells.

These fast-growing cells are cancer cells.

They also attack other fast-growing cells like those in bone marrow and the gastrointestinal tract, leading to such side effects as anemia, infections, nausea and diarrhea.

Because the chemotherapy kills other fast-growing cells in the body, you may have hair loss and mouth sores.

Chemotherapy for cancer, on the other hand, interferes with anagen, the growing phase, because the drugs are designed to disable fast-growing cells.

As such, they can be more specific than a chemical drug that simply kills fast-growing cells.