Chemoprevention
The use of natural or laboratory-made substances to prevent a disease such as cancer.
The regular use of aspirin is known to reduce the risk of the polyps from which colorectal cancer arises.
This is an instance of chemoprevention.
The term chemoprevention was coined to parallel the term chemotherapy.
Chemoprevention prevents and chemotherapy treats.
Chemoprevention is also called chemoprophylaxis.