Alopecia is the medical term to describe hair loss. Cancer cells grow rapidly and uncontrollably. Chemotherapy affects any cell that grows rapidly, such as hair cells. Hair falls out at the root when the hair bulb shrinks. Hair falls out spontaneously, during combing, or breaks at the bulb.
Chemotherapy affects all body hair.
Since scalp hair is an active growth phase more often than any other body hair, this is the hair that chemotherapy most often affects. Hair loss can range from thinning to complete baldness and the degree of hair loss is drug and dose dependent. This condition is always temporary. Radiation therapy affects hair only in the area where the radiation has been administered. With radiation therapy, hair loss may or may not be permanent and is dose and site dependent.