My daughter has uneven breasts and strange markings on the upper left side of her left breast. could this be a sign of breast cancer?

Have her examined: Probably skin abnormality. The possibility of breast cancer at her age is near nil.

Doubt it: It is not unusual for young women to have some asymmetry or unevenness as they develop.Some will go on to deal with this after puberty if the smaller side does not fill in. Surface markings at that age represent skin issues, not deeper breast issues.The more common are stria or stretch markings. Her regular primary care doc is a good place to start.