When a patient’s scalp is cooled, two physiologic reactions occur:

(1) The blood vessels in the localized scalp area constrict (vasoconstriction): the narrowed blood vessels limit the amount of chemotherapy agents delivered to scalp area.

(2) The metabolism slows down: a reduced scalp temperature causes normal cellular activity in the localized scalp area to slow dramatically. This means that much fewer chemotherapy agents become absorbed by the hair cells and damage is significantly reduced.