If a 15-year-old has a lump on one breast, is it dangerous? what are the chances that it is a breast cancer?

Very small: Most breast lumps on 15 year old patient a not dangerous. It is best to get it checked by doctor.

Highly Unlikely : It is fairly common for teenage girls to note a "breast lump." the most common causes are benign - fibroadenoma or cyst. Breast cancer is extremely rare in teenagers. Consult your primary care for reassurance. They may order a breast ultrasound to verify.

Rare: It would be exceedingly rare for a 15 year old to develop breast cancer. You should let your friendly primary care physician know of your concerns.

Extremely rare: Most common cause of breast mass in teenagers is fibroadenoma.