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Dutch MRI Screening Study: Ongoing differences observed between BRCA1 and BRCA2 tumors
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Breast cancer patients with BRCA1-mutated tumors may require different screening, prevention and treatment strategies than patients with BRCA2 mutations, according to recent results.
The Dutch MRI Screening Study focused on early detection of hereditary breast cancer. The current results include analyses of BRCA1 and BRCA2 mutation carriers and early survival outcomes.
The 2,157 eligible women had a cumulative lifetime risk for breast cancer of more than 15%. These women received biannual clinical breast examinations and annual mammographies and MRIs.
Participant subgroups included 599 women who carried a gene mutation (50%-85% cumulative lifetime risk) and two familial groups with high (30%-50%) or moderate (15%-30%) cumulative lifetime risk.
During 4.9 years of follow-up among the mutation carriers, there were 97 primary breast cancers detected. Cancers were followed up during a median of 5 years from diagnosis.
MRI had a sensitivity of 77.4% in detecting invasive cancer vs. a 35.5% sensitivity rate for mammography (P<.00005). However, MRI was not more sensitive in detecting ductal carcinoma in situ.
Mammography sensitivity was 25% in the BRCA1 group vs. 61.5% in the BRCA2 group, 45.5% in the high-risk group and 46.7% in the moderate-risk group. Tumor size at diagnosis was 1 cm or smaller in 21.4% of patients in the BRCA1 group vs. 61.5% of patients in the BRCA2 group, 40.9% of patients in the high-risk group and 63.6% of patients in the moderate-risk group.
The proportion of ductal carcinoma in situ was lower in the BRCA1 group compared with the other three groups (6.5% vs. 18.8%, 14.8%, 31.3%), as was the proportion of interval cancers (32.3% vs. 6.3%, 3.7%, 6.3%).
Age at diagnosis younger than 30 years was observed in 9.7% of BRCA1 patients vs. 0% of patients in the other groups.
Among the 42 patients who had invasive breast cancer with BRCA1 or BRCA2 mutations, cumulative distant metastasis-free survival at 6 years was 83.9% (95% CI, 64.1-93.3). In this same group, OS at 6 years was 92.7% (95% CI, 79-97.6).
Among 43 patients in the high- or moderate-risk familial subgroups, cumulative distant metastasis-free survival and OS were 100%, according to the results.
“BRCA1-associated tumors behave completely differently from BRCA2-associated tumors and those from the other risk groups,” the researchers wrote. They said a modification of screening schedules or an application of more specified treatment regimens or preventive measures may improve outcomes among women with BRCA1 mutations.
For more information:
- Rijnsburger AJ. J Clin Oncol. 2010;28:5265-5273.