There has been significant research into the science behind scalp cooling, which has shown that there are several potential mechanisms, but the most commonly recognised is vasoconstriction. The blood vessels of the scalp are restricted, causing them to narrow, reducing the amount of chemotherapy reaching the hair follicles which in turn causes less hair to be lost. The amount of hair that scalp cooling can help to retain will vary depending on the chemotherapy drug type. Everyone who scalp cools will experience some shedding, even those with the highest levels of hair retention, but the hope for most patients is that they will have enough hair that a stranger wouldn't know they were going through chemotherapy. For patients receiving Taxotere/Docetaxel, scalp cooling has been proven to prevent a patient from suffering pCIA - Persistent Chemotherapy Induced Alopecia. In other words permanent hair loss.

Scalp cooling has also been proven to ensure faster and healthier hair regrowth, even for patients that sustain significant hair loss. Continuing to scalp cool through chemotherapy treatment, regardless of hair retention, will provide ongoing protection to a patient's hair follicles. This is also the case for patients who may be at risk of persistent alopecia.

This is a very basic outline but if you want a more in-depth scientific explanation you can get that directly from the Paxman Scalp Cooling website here https://paxmanscalpcooling.com/science/