BRCA1 Carriers May Require More Frequent Imaging
1. As reported in Family Practice News, January 15,2008
2. Midterm report of the Dutch MRI Screening Study, as reported at the San Antonio Breast Cancer Symposium
3. A radomized study of the utility of mammography and MRI in screening women at increased risk breast cancer, involving 2,177 Dutch women, begun in 1999. Median follow up at the time of this report is 5.3 yrs.
4. The protocol is for clinical breast examination every 6 months with yearly MRI and mammography at the same visit. The participants were encouraged to perform self breast examinations.
A. To date, 94 breast cancers have been found. The detection rates were 70.3 cases per 1,000 BRCA 1 carriers, 92.8 cases per 1,000 BRCA 2 carriers, 28.7 cases per 1,000 in the highest risk group, and 32.5 cases per 1,000 in the moderate risk group.
B. The most surprising findings were the differences in the breast cancers arising in BRCA 1 vs BRCA 2 mutation carriers. Cancers in the BRCA 1 carriers tended to occur at a younger age, they were larger when found, they grew more rapidly, and they were significantly less likely to be ductal carcinoma in situ (DCIS) the the breast cancers of the BRCA 2 carriers.
C. Thirteen of the 16 breast cancers detected among study participants in the intervals between screenings occured in BRCA 1 carriers.
D. Seven per cent of the breast cancers in the BRCA 1 group were DCIS , compared with 37% in the BRCA 2 carriers.
E. 31% of the invasive tumors in the BRCA 1 group were greater than 2 cm in size, as were 10% of the BRCA 2 group.
F. Fifty seven percent of all breast cancers in the BRCA 1 group occured before age 40, as did 44% in the BRCA 2 group.
G. As to screening methods; 40% of the breast cancers were found only with MRI, 25% with MRI and mammography, and 18% by mammography screening alone. (The authors state this points out the complementary nature of the two screening methods)
H. Mammography, in this study, found many more cases of DCIS. (67% vs 33%)
I. 30% of all cancers detected in this screening program were lymph node positive at the time of discovery.