Breast lump in a 16 year old female, could this be cancer?

Not likely: Although possible, breast cancer is rare in premenopausal women, and it is extremely, extremely rare in teenagers. More likely, the lump is some active breast tissue in the maturing breast, or a benign mass, such as a fibroadenoma or fibrocystic disease. For reassurance, you should see your primary care physician; if he/she is concerned, referral to a general surgeon would be in order.