Parents may not have the emotional energy to provide the usual support, love, and authority. Teenagers can feel torn between expressing independence and a need to remain close to the sick parent. All of us want to shield our children from pain. But their insight is greater than most people realize, and trying to keep a complex situation such as cancer a secret, is practically impossible. A simple and straight-forward explanation, geared to the children's age and ability to understand, will establish an open and honest path for communication.
Children have amazing abilities to cope with situations they understand.
However, when their normal world is turned upside down and whispered conversations go on behind closed doors, they often imagine things that are worse than reality. Childrens' ability to process information about their mother's breast cancer depends on their age, and the parent will need to adjust her explantion accordingly. Being direct is often the best approach. I have a disease called cancer. A close and loving aunt or uncle or friend might be able to explain things more comfortably.