Table 2.

SIRs for breast cancer in first-degree relatives of cancer patients, by patients' cancer site and BRCA mutation status

Patient's BRCA statusPatient's cancer site
P*
Breast cancer (n = 670)
Ovarian cancer (n = 342)
No.OESIR (95% CI)No.OESIR (95% CI)
BRCA1-positive48171.610.6 (5.2-21.6)76103.03.3 (1.4-7.3)0.02
BRCA2-positive47122.74.4 (1.1-16.9)
Negative/untested1,883387258.01.5 (1.2-1.8)8815247.31.1 (0.8-1.6)0.12
All1,978416260.01.6 (1.3-2.0)9576251.71.2 (1.0-1.6)
  • Abbreviations: O, number of cancers; E, expected number (based on U.S. incidence rates).

  • * Two-tailed test of similar SIRs in relatives of breast and ovarian cancer patients.

  • BRCA2 testing was not done among ovarian cancer patients.