Why does one of my breasts sag more than the other? could this be related to breast cancer? 33 year old female.

Not certain cancer.: The left and right sides of our bodies are never perfectly symmetrical so the fact that the breasts are not mirror images of each other is not concerning. However, if you're saying that one of your breasts looks different than it usually would look, then you would really need an investigation including an exam and mammogram at least.