Among women with BRCA1 mutation, age younger than 40 at time of
first breast cancer has been associated with significantly higher risk for
contralateral breast cancer compared with those diagnosed at age 50 or older.
The finding should help inform physicians as to recommending bilateral
mastectomy to patients with BRCA1/2 mutations.
A group of researchers from sites throughout Europe performed this
retrospective cohort study from 1996 to 2008. It included 2,020 women with
unilateral breast cancer. Index patients comprised 978 of the total; relatives
comprised 1,042. All were from families who had a BRCA1 or BRCA2
mutation. The researchers used Cox regression analysis to examine the
relationship between age at first breast cancer and time from first to
bilateral breast cancer.
For patients from families with BRCA mutations, the risk for
contralateral breast cancer 25 years after first breast cancer was 47.4% (95%
CI, 38.85%-56%). Those in families with BRCA1 mutations had a 1.6-fold
higher risk for contralateral cancer than women from families with BRCA2
mutations (95% CI, 1.2-fold to 2.3-fold).
Although younger age at time of first breast cancer conferred a
significantly higher risk for later contralateral breast cancer in women with
BRCA1 mutations, there was no statistically significant difference in
risk for women with BRCA2 mutations.
“After 25 years, 62.9% (95% CI, 50.4% to 75.4%) of patients with
BRCA1 mutation who were younger than 40 years of age at first breast
cancer developed contralateral breast cancer, compared with only 1.6% (95% CI,
5.3% to 33.9%) of those who were older than 50 years of age at first breast
cancer,” the researchers wrote.
In an accompanying editorial, Judy E. Garber, MD, MPH, from the
Dana Farber Cancer Institute, and Mehta Golshan, MD, from Brigham and
Women’s Hospital, wrote that this study provides important data that
should help inform the cancer care team as to recommending bilateral mastectomy
at the time of first breast cancer diagnosis for women with BRCA
mutations.
This study “provides powerful figures that should compel the breast
cancer care team to consider the issue of management of the opposite
breast,” Garber and Golshan wrote.
“The risk of contralateral breast cancer and its management are
already part of many discussions at initial diagnosis and should be emphasized,
but not overemphasized. As Greaser et al have shown, knowledge of
BRCA1/2 mutation status may inform this aspect of the discussion,
providing reassurance to women whose genetic testing is negative and stratified
information to mutation carriers on which to base some difficult
decisions,” they wrote.
Graeser MK. J Clin Oncol. doi:
10.1200/JCO.2009.25.1652.