BRCA mutations just as prevalent in DCIS as in invasive breast cancer

May 1, 2005

Women with BRCA1 and BRCA2 mutations are not only at greater risk for invasive breast cancer (IBC); the latest research suggests these mutations also increase the threat of ductal carcinoma in situ (DCIS), according to a case-control study conducted in Connecticut.

Women with BRCA1 and BRCA2 mutations are not only at greater risk for invasive breast cancer (IBC); the latest research suggests these mutations also increase the threat of ductal carcinoma in situ (DCIS), according to a case-control study conducted in Connecticut. This suggests that women with DCIS who have suggestive personal and family histories should be screened for the mutation and followed in the same manner as women diagnosed with IBC.

Researchers found that of 369 women with DCIS, three (0.8%) and nine (2.4%) had disease-associated mutations in BRCA1 or BRCA2, respectively. One woman had mutations in both genes.

Compared with women without the mutations, women with the mutations were 3.7 times more likely to report a first-degree relative with breast cancer (OR 3.7; 95% CI: 1.1–12.4) and more than 10 times as likely to report at least one first-degree relative diagnosed with breast cancer at younger than 50 years of age (OR 10.6; 95% CI: 3.0–37.0). Women with the mutations were also more than three times as likely to be diagnosed before age 50 (OR 3.4; 95% CI, 1.0-11.7); mean age at onset for BRCA1 or –2 mutation carriers was about 5 years earlier than for noncarriers. And carriers were more likely than noncarriers to be diagnosed with ovarian cancer, with two of 11 carriers (18.2%) diagnosed with ovarian cancer (at 53 and 71 years) after being diagnosed with DCIS.