What is the youngest age at which you can get breast cancer?

Almost any age: To my knowledge, the youngest breast cancer patient was a toddler. However, in general, most females are diagnosed with breast cancer after the age of 40, which is one reason why we generally recommend screening mammograms starting at age 40. The exception are breast cancer mutation carriers, who commonly develop breast cancer in their 20's-30's and require earlier screening/prevention efforts.

Depends: That depends on multiple variables like family history, genetics (brca gene), environment (cigarettes, alcohol), diet, etc. Please see this link for a more thorough explanation, and then you should discuss this with your doctor. http://www.mayoclinic.com/health/breast-cancer/ds00328/dsection=risk-factors.

Breast Cancer Age: Any age is possible for Breast Cancer though it would be rare in children. It is more common as you age and with certain risk factors such as genetic propensity, obesity with overly large breasts, smokers, radiation exposure, and other factors

BRACA dependent: Since it takes many hits and time for a cell to transform, breast cancer is most frequent over the age of 40. With BRACA mutations congenital breast malignancies can develop under the age of 20. Any mass appearing in a young womans breast must be evaluated as a fibroadenoma or developing malignancy. Patients without BRACA have been seen as young as 17 y.o.