While only 5% of breast cancer cases are in women younger than 40, it tends to be more aggressive and less likely to respond to treatment in younger women. It can also lead to problems with sexuality, fertility and pregnancy after receiving treatment for breast cancer. It’s important to pay attention to the warning signs no matter how old you are. One of the challenges for younger women is that they tend to ignore symptoms, thinking they’re too young to have breast cancer. Delaying the diagnosis can lead to delayed treatment and decreased chances of survival. If you have lumps or unusual discharge, get your breasts checked as soon as possible.