A study showed that the length of time a woman survives after a breast cancer diagnosis is related to how long any of her first-degree relatives survived after breast cancer. For example, if her mother or sister lived for more than 5 years after diagnosis, then a woman also tended to live more than 5 years after her own diagnosis. This link appears stronger between sisters than between mothers and daughters. But the mother-daughter link was stronger when the mother was diagnosed before she was 70.
Research has shown that genetic differences are probably why breast cancer risk, response to treatment, and prognosis are different for all women and different among ethnic groups. In this study, genetic differences are probably why first-degree relatives have similar survival times. Unfortunately, there's still much more research to be done to understand exactly which genes are involved and how these genes affect prognosis. In the meantime, if you've been diagnosed with breast cancer and have a first-degree relative with breast cancer, discuss this information with your doctor. This family history might be important when you and your doctor decide on the best treatment plan for YOU.