Difference in the age of onset of breast cancer between mothers and daughters in hereditary breast cancer.

Mean age of cancer development in mothers and daughters in the three groups, BRCA1, BRCA2 and BRCAX, of hereditary breast cancer. Statistical significance of the difference between mothers and daughters was estimated by t-tests.s.d. Standard deviation. Bilateral t-test was performed to assess the significance of the differences between mothers and daughters. Values for the t-statistic and the p-value for the t-test are indicated.