SAN ANTONIO — Breast cancer prognosis appears to have a strong and previously unrecognized inherited component, Dr. Mikael Hartman said at a breast cancer symposium sponsored by the Cancer Therapy and Research Center.
His study of 2,787 mother-daughter and 831 sister pairs with breast cancer showed that 5-year breast cancer-specific mortality was 60%–80% greater among first-degree relatives of a woman who died of the disease within 5 years of diagnosis than in those whose affected mother or sister had a good prognosis.
“Information about the outcome of breast cancer among affected first-degree relatives may be relevant for optimal clinical management of women with newly diagnosed breast cancer,” said Dr. Hartman of the Karolinska Institute, Stockholm.
Among the 831 pairs of sisters, each with breast cancer, 5-year breast cancer-specific survival was 88% if the older affected sister was alive within 5 years of diagnosis, but only 70% if she was not.
After adjusting for potential confounders, including age at cancer diagnosis, treatment era, nulliparity or age at first live birth, and socioeconomic status, the risk of dying because of breast cancer within 5 years after diagnosis was 80% greater in women whose sister died of breast cancer less than 5 years following her diagnosis than in those whose sister had a good-prognosis form of the disease as defined in a multivariate model.
Similarly, the adjusted risk of breast cancer-specific mortality was 60% higher in the daughters of mothers with a poor-prognosis form of breast cancer, compared with mothers with a good prognosis, he continued. Concordance with regard to prognosis was strongest among mother-daughter pairs in whom the mother was diagnosed before age 40.
The determinants of this newly recognized inherited component of breast cancer prognosis are likely to turn out to be genetic, Dr. Hartman said.