No matter what type of cancer a person has, when it is known to have metastasized doctors will usually treat the person immediately with angiostatins and endostatins. why is this done even if they don't know what caused the cancer

Targeting cancer stem cells (CSCs) is difficult. The growing body of evidence suggests that in many cases cancerous cells originate from a single cell with stem cell characteristics. Thesefindings should have a profound effect on the treatment of cancer. Traditional cancer treatment is based on the 

Apparently the correct answer is carbohydrates